- Ninguna Categoria
Roadway & Parking Lighting: IES Recommended Practice RP-8-21
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ANSl/IES RP-8-21 Recommended Practice: Lighting Roadway and Parking Facilities Publ ication of this Reco m m e n ded Practice has been ap p roved by the IES. S u g gestions for revisions should be d i rected to IES. Prepared by: The Roadway Lighting Committee Copyright 2022 by the Illuminating Engineering Society. Approved by the /ES Standards Committee, November 16, 2021 as a Transaction of the Illuminating Engineering Society. Approved by the American National Standards Institute as an American National Standard, November 18, 2021. Al l rights reserved. No part of this publ ication may be reproduced in any form, in any electronic retrieval system or otherwise, without prior written permission of the I ES. Publ ished by the I l l u minating Engineering Society, 1 20 Wal l Street, New York, New York 1 0005. IES Standards and G uides are developed through comm ittee consensus and prod uced by the IES Office in New York. Careful attention is given to style and accuracy. If any errors are noted in this document, please forward them to the Director of Standards, at [email protected] or the above address, for verification a nd correction. The IES welcomes and u rges feedback and comments. Printed in the Un ited States of America. ISBN# 978-0-87995-41 6-1 DISCLAIMER IES publications are developed through the consensus standards development process approved b y the American National Standards Institute. This process brings together volunteers representing varied viewpoints and interests to achieve consensus on lighting recommendations. While the IES administers the process and establishes policies and procedures to promote fair­ ness in the development of consensus, it makes no guaranty or warranty as to the accuracy or completeness of any information published herein. The IES disclaims liability for any injury to persons or property or other damages of any nature whatsoever, whether special, in­ direct, consequential or compensatory, directly or indirectly resulting from the publication, use of, or reliance on this document. In issuing and making this document available, the IES is not undertaking to render professional or other services for or on behalf of any person or entity. Nor is the IES undertaking to per form any duty owed by any person or entity to someone else. Anyone using this document should rely on his or her own independent judgment or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstances. The IES has no power, nor does it undertake, to police or enforce compliance with the contents of this document. Nor does the IES list, certify, test or inspect products, designs, or installations for compliance with this document. Any certification or statement of compliance with the requirements of this document shall not be attributable to the IES and is solely the responsibility of the certifier or maker of the statement. AMERICAN NATIONAL STANDARD Approval of an American National Standard requires verification by ANSI that the requirements for due process, consensus, and other criteria have been met by the standards developer. Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially affected interests. Substantial agreement means much more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made toward their resolution. The use of American National Standards is completely voluntary; their existence does not in any respect preclude anyone, whether that person has approved the standards or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standards. The American National Standards Institute does not develop standards and will in no circumstances give an interpretation to any American National Standard. Moreover, no person shall have the right or authority to issue an interpretation of an American National Standard in the name of the American National Standards Institute. Requests for interpretations should be addressed to the secretariat or sponsor whose name appears on the title page of this standard. CAUTION NOTICE: This American National Standard may be revised at any time. The procedures of the American National Standards Institute require that action be taken to reaffirm, revise, or withdraw this standard no later than five years from the date of approval. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute. Officers and members of the Roadway Lighting Committee For the comm ittee-i nfo page in RP-8-21 . (No others g roups or recognitions are to be incl uded this time.) Prepared by the Roadway Lighting Committee Martin A. Aitkenhead, Chair Joe D. Marsh, Vice Chair Mark Seppelt, Secretary Members C. K. Andersen N. Dittman R. Larivee A. D. Silbiger L. A. Asselin M. A. Dudas 0. Letamendi W. A. Smelser R. Bhagavathula K. Fitzmaurice G. G. Lister M. Smolyansky J. T. Brown J. Frazer D. S. Mclean R. Stemprok M. Bucci R. S. J ones K. Molloy M. Tedesco G. Chelvanayagam J. J. Juzwiak M. N. Maltezos G. H. T hiesse J. Cheung H. Kashaninejad E. H. Morel U. Thurairajah N. E. Clanton R. W. Kauffman R. Rainer S. A. Wentworth S. Coyle S. N. Lansford J. Robinson R. W. Yeager K. Aiken R. Gibbons A. -M. E. Lemieux J. S. Petty R. Benekohal D. R. Howard D. Lenasi L. C. Radetsky G. J. Brunet G. Hyde C. J. Leone T. Ross R. D. Clear J. Jiao M. Letourneau P P. Sabau J. J. Dacosta K. S. Kang P. Lutkevich J. A. Simmers C. Donkin D. M. Keith L. E. Lutley L. F. Smith A. L. Duma M. T. Kelly D. R. Monahan M. -A. Vachon J. T. Weaver Advisory Members R. R. Ebbert R. Kent C. M. Ockunzzi C. F alkowski E. J. Kramer U. Padmanath E. S. Yao J. S. Farsatis A. M. Kuczkowski D. Passariello S. Zarling J. Faught C. Kwong M. R. Pearse Please refer to the !ES website for possible Errata: http://store.ies.org/errata-and-addenda/ CONTENTS Introduction to this Recommended Practice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I History of the Document . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I How to Use this Recommended Practice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I I Part 1 - Fundamentals Chapter 1: I ntroduction to Roadway Lighting 1 .1 Why Light? 1 .2 H u man Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 -1 1 .3 The Value of Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 -2 1 .3.1 1 -1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Key Benefit - A Red uction I n Crashes 1 -3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 .3.2 Cost- Benefit Analysis of Roadway Lighting 1 . 3.3 The Need for Good Desig n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 -4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 -4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 -5 1 .4 Lighting Warrants 1 .5 Energy Conservation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 -5 1 .6 Environmental Factors 1 .7 Alternatives to Lighting 1 .8 Reference Lighting Organizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 -7 Add itional Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References for Chapter 1 1 -5 1 -6 1 -8 1 -9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chapter 2: Vision and Fundamental Concepts 2.1 Light and the Visible Spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2.2 Basic Principles of Vision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 2.3 2.2.1 Structure of the Eye 2.2.2 Fu nction of the I ris and Pupil 2.2.3 Fu nction of the Lens 2.2.4 Fu nction of the Retina 2.2.5 Adaptation 2.2.6 Accom modation 2-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5 Visibi lity Fundamentals a nd Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5 2.3.1 Contrast 2.3.2 Visua l Acuity 2.3.3 Glare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7 2.3.4 Spectral Effects and Mesopic Vision 2.3.5 Effects of Age on Vision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7 2-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4 Light Sou rces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 0 2.5 Measurements 2.6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5.1 Measurement Considerations 2.5.2 Units and Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5.3 Principles of Laboratory Photometry Photometric Test Reports 2.5.5 Relative and Absol ute Photometry Luminaire Classification Systems 2-1 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2 . . . . . . . 2-1 7 . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-17 . . . . . . Longitud inal Light Distribution (S, M, L) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.6.2 Tra nsverse Light Distribution (Types I - VS) 2.6.3 The I ES Lu minaire Classification System (LCS) and B UG Ratings 2.6.4 Variations and Comments References for Chapter 2 2-1 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5.4 2.6.1 2-1 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-26 Chapter 3: Calculations 3.1 3.2 3.3 3.4 Calcu lation Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 3.1 .1 Road Geometrics 3.1 .2 Road Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 .3 Pedestrian Conflict . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 3-1 3.1 .4 Lam p or Luminaire Lumens . . . . . . . . . . . 3.1 .5 Pavement Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 . . . . . . . . . . . . . . . ... . . ............... . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 3.1 .6 Light Loss Factors (LLF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2 3.1 .7 Luminaire Position and Orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7 3.1 .8 I m pact of Vehicle Head l i g hts 3.1 .9 Change in Physical Surrou n d i ngs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7 3.1 .1 0 I m pact of Trees on Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7 Roadway Lighting Metrics - General I nformation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 0 3.2.1 Assu med and Standard Conditions 3.2.2 Accuracy of Calcu lations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 1 3.2.3 Selection of a Grid and Luminaire Location Geometry for Calcu lations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 1 3-1 1 Calcu lation of Roadway Pavement Luminance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 6 3.3.1 The r-Ta bles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 6 3.3.2 Pavement Classification Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-21 3.3.3 Form ulas and U n its . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-21 3.3.4 Sum mary of Pavement Lumina nce Data 3.3.5 Example of Determi n i ng Val id Luminaire-Point Combinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-21 Calcu lation of Roadway Pavement llluminance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-25 3.4.1 Formulas and U n its . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-26 3.4.2 Sum mary of Pavement II l u minance Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-26 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-26 3.5 Uniformity Ratios 3.6 Two Metrics of Glare in Roadway Lighting . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-26 3.6.1 Veiling Lumi nance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-26 3.6.2 Threshold I ncrement (Tl) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-27 3.7 3.8 3.9 Small Target Visibility (STV) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-28 3.7.1 Calculating Target Luminance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-28 3.7.2 Calculating Target Visibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-30 3.7.3 Sum mary of Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-30 Vertical lllu minance Tu nnel Calcu lations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-30 3-31 3.9.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-31 3.9.2 Selection of a Grid for Tunnel Lighting Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-32 3.9.3 Computation of the Di rect Component . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-34 . . . . . . 3.9.4 Discretization of the Tunnel Su rfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-34 3.9.5 Computation of the Indirect Component of l l l u m i nance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-35 3.9.6 Computation of Surface Element Luminance and Reflected I ntensity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-36 3.9.7 Computation of the Indirect Component of Vei l i n g Luminance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-37 Add itional Reading References for Chapter 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-39 3-41 Chapter 4: Obtrusive Light 4.1 I ntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 4.2 Defining Obstrusive Light 4.3 Light Trespass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2 4.4 4.5 . . • . . . • . . . . . . . . . . . . . . . . . . . . . . • . . . . . • . . . • . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . 4-1 4.3.1 Recommended Acceptable Levels of Spi l l Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3 4.3.2 Measurement and Calculation of Spi l l Light . . . . . . . . 4.3.3 M itigation of Spill Lig ht. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5 Glare . . . . . . . . . . . . . . . . . . . . ............... . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4 4-5 4.4.1 Calcu lation and Measurement of Offsite G l a re . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5 4.4.2 M itigation of Glare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5 Sky Glow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5 4.5.1 Sou rces of Sky Glow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6 4.5.2 Sky Glow Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7 4.4.3 M itigation of Sky G l ow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7 4.6 Obtrusive-Light Regulations 4.7 I mpacts From Off-Roadway Obtrusive Light . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . • . . . • . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . 4-8 4-9 4.7.1 Some Conditions Wherein Obtrusive Light Might Be Created for Road Users . . . . . . . . . . . . . . . . . . . . . . . 4-9 4.7.2 Mitigating the Effects of Obtrusive Light From Off-Roadway Sou rces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9 4.8 Lighting I mpacts on Species and Habitat 4.9 4.1 0 I mpacts of Exterior Lighting on Airports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Potential Health Im pacts of Lighting on Humans 4-9 . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 0 . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 0 References for Chapter 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 1 Chapter 5: The Planning and Design Process 5.1 5.2 Typical Situations That May Require Lighting Design Design Issues 5.2.1 . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2 5.2.2 Cost 5.2.3 Optim ization of Lighting 5-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4 5.2.4 Aesthetics 5.2.5 Environmental Considerations 5.2.6 Site Conditions 5.2.7 Col l ision Data and Investigations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6 5.2.8 Adaptive Lighting 5.2.9 Prioritizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6 5.3 Lighting Master Plans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7 5.4 The Design Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9 5.5 5.6 5.4.1 Perform Pre-design 5.4.2 I nvestigate Site Conditions 5.4.3 Define Lighting Design Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 0 5-1 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12 5.4.4 Perform Lighting Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-13 5.4.5 Perform Electrical Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 5 5.4.6 Perform Geotechnical and Structural Design 5.4.7 Prepare Plans, Specifications, and Estimates (PS&E) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 9 5.4.8 Bid or Tender 5.4.9 Construction 5.4.1 0 Post-construction: Drawings 5.4.1 1 Post-construction: Integration and Comm issioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 9 5-20 Calculating Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-20 5.5.1 Capital Cost 5.5.2 Operating Costs 5.5.3 Life Cycle Cost 5.5.4 Life-Cycle Cost Calculation Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-21 Verification of Lighting Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-21 5.6.1 Verification by Calculation 5.6.2 Field Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-21 5.6.3 Electrical System Verifications 5.6.4 Field Verification of Lighting Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-24 5-24 References for Chapter 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-25 Chapter 6: Lighting System Components 6.1 6.2 Selecting and Specifying Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 6.1 .1 Sources for I nformation on Available Equipment 6.1 .2 The I mportance of Quality i n Product Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 6.1 .3 Other Key Selection Criteria 6.1 .4 Capital (Supply) Cost in Product Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2 Types of Lighting and Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3 6.2.1 Bollard Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.2 Decorative Lighting 6.2.3 H orizontal Arm-Mou nted Lighting 6.2.4 H ig h-Mast Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3 6-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6 6.3 6.2.5 Wa l l Mou nted Lighting 6.2.6 Roadway Lighting on Utility Poles 6.2.7 Flood l i g hting 6.2.8 In- Roadway Lights 6.5 6.6 6.7 6.8 6.9 6-1 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Light Emitting Diode (LED) 6-1 8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3.2 High Intensity Discharge ( H I D) 6.3.3 Fluorescent 6.3.4 Ind uction (E) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-22 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-22 6.3.5 Plasma 6.3.6 Low Pressure Sod i u m (LPS) 6.3.7 I ncandescent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-23 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-23 Luminaires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-23 . 6.4.1 Luminaire Photometric Performance 6.4.2 Special Considerations for Roadway Luminaires 6.4.3 Alternative Power Sou rces 6-24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-24 Luminaire Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-25 . 6.5.1 Housings 6.5.2 LED System Components 6.5.3 HID and Fluorescent System Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-25 6-25 6-27 Electrical Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-28 6.6.1 Electrical System Components 6.6.2 Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-28 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-29 6.6.3 Metering 6.6.4 Power Distribution Cabi nets 6.6.5 Power Qua lity Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-29 6-30 6-31 Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-32 . . . 6.7.1 Typical Conductor Types 6.7.2 Overcurrent Protection 6.7.3 Voltage Drop and Fau lt Current Calcu lations 6.7.4 G rounding and Bonding 6.7.5 Conduit 6.7.6 Junction Boxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-33 6-33 Fou ndations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-33 . 6.8.1 Concrete Foundations 6.8.2 Stee l Screw-In Type Foundations 6.8.3 Direct- Bu rial Poles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-35 Poles and Related Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-35 . 6.9.1 6.1 0 6-1 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Light Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 6 6.3.1 6.4 6-1 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pole Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-35 6.9.2 Pole Placement (Spacing) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-37 6.9.3 Clear Zone Req uirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-38 6.9.4 Breakaway Bases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-38 6.9.5 Pole Attachment Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-38 Roadway Lighting Control Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-39 6.1 0.1 Control Technolog ies 6.1 0.2 Adaptive Lighting Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-39 6-44 6.1 0.3 Adaptive Lighting Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-49 6.1 0.4 Integration a nd Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-51 References for Chapter 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-54 Chapter 7: Standards and Codes 7.1 Local, Regional, and National Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1 7.2 Origins of Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1 7.3 North American Standards Organizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2 7.3.1 Canadian Organizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2 7.3.2 U.S. Organ izations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3 7.3.3 Mexica n Organizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4 7.3.4 M u ltinational Organizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4 References for Chapter 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6 Chapter 8: Computer Applications 8.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1 8.2 Limitations of Computer Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1 8.3 Basic Lumina nce Ca lculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1 8.4 Complex Roadway Calcu lations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3 8.5 Typical llluminance Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3 8.6 Calcu lated Digital Renderings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4 8.6.1 The Rendering Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4 8.6.2 Uses for Renderi ngs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-5 8.6.3 Limitations of Renderings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-5 . . . . . . . . . Chapter 9: Maintenance and Operations 9.1 9.2 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1 9.1 .1 Funda mental Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1 9.1 .2 Procedu res Before Beginning Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1 9.1 .3 Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2 9.1 .4 Equi pment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2 9.1 .5 Traffic Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2 9.1 .6 Environmental Protection and Health and Safety H azards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2 9.1 .7 Contact Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2 Luminaires and Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4 9.2.1 Light Source Life . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4 9.2.2 Light Source Lumen Depreciation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4 9.2.3 Lumen Dirt Depreciation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4 9.2.4 Leveling and Alignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-5 . . . . 9.2.5 9.3 9.4 9.5 9.6 9.7 9.8 9.1 0 9-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2.6 Line Voltage 9.2.7 Obstruction of Light and Photocontrols by Foliage 9-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-6 Poles a nd Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-8 9.3.1 Paint or Coating 9.3.2 Vibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-9 Maintenance of Conventional Lighting Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-9 9.4.1 Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4.2 Corrective Mai ntenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-9 9-1 0 Mai ntenance of High-Mast Lighting Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1 0 9.5.1 Preventive Maintena nce . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1 0 9.5.2 Corrective Mai ntenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1 1 Maintenance of Tunnel Lighting Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1 1 9.6.1 Preventive Maintena nce . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1 1 9.6.2 Corrective Mai ntenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1 3 Troubleshooting, Repair, and Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-14 9.7.1 Procedures for Night Patrol Service 9.7.2 I nformation Gathering 9.7.3 Troubleshooting LED Lu minaires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-14 9.7.4 Troubleshooting H PS Lum i n a i res . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-14 Mai ntenance Management System Guideli nes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1 6 9.8.1 9.9 Controls Inspections, Patrols, and Public Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.8.2 Requ i rements 9.8.3 Operations and Asset Management via Networked Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1 6 9-1 7 9-1 8 Light Source Failure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1 9 9.9.1 Light Emitting Diode (LED) Fai l u re 9.9.2 H i g h Intensity Discharge Lam p Fai lure 9.9.3 Low Pressure Sodium (LPS) Lam p Fa i l u re . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-19 9-19 9-20 9.9.4 I nca ndescent Lamp Fai l u re . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-20 9.9.5 Basic Relamping Practices and Choices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-20 Relamping With LED Retrofit lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-21 9.11 Disposal of Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-21 9.12 New Light Sou rces and Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-22 9.13 Economics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-22 9.1 3.1 Light Loss Factors 9.1 3.2 Record Keeping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-22 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-22 9.1 3.3 G roup Versus Spot Relamping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-22 9.13.4 Maintenance Budgets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-23 9.1 3.5 Energy Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-23 9.14 Methods of Contracting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-23 9.1 5 Equipment Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-24 Additional Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-25 References for Chapter 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-25 Part 2 - Design Chapter 10: Highways and I nterchanges 1 0.1 Roadway Lighting - General . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0.1 .1 The Purpose of Roadway Lighting 1 0.1 .2 Hig hway Lighting Versus Street Lighting 1 0-1 1 0-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0.2 Classifications and Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-2 1 0.3 1 0.4 1 0.2.1 Hig hway Defi nitions 1 0.2.2 Pavement Classification 1 0.6 1 0.7 1 0-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-3 1 0.3.1 Visual Task 1 0.3.2 G l a re, Light Trespass, and Sky G l ow Issues 1 0.3.3 The Effects of Headlig hts 1 0.3.4 Spectral Considerations 1 0.4.1 1 0.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Design Considerations Design Issues 1 0 -2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-4 Cu rves and Steep Grades 1 0.4.2 H ig hway I nterchanges 1 0.4.3 H ig h-Mast Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-6 Lighting Recom mendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-8 1 0.5.1 General 1 0.5.2 Lighting Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Design Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-1 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-1 2 1 0.6.1 Recommended Calculation Methods 1 0.6.2 Recom mended Luminance Calculation Method for Hig hways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-1 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-1 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-1 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-1 5 Design Example - Freeway Additional Reading 1 0-8 References for Chapter 1 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-1 5 Chapter 1 1 : Street Lighting 1 1 .1 Street Lighting 1 1 .2 Walkways and Bikeways in the Public Right of Way . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -1 1 1 .3 Classifications and Definitions 1 1 .4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 .3.1 Street Classifications 1 1 .3.2 Pedestrian Activity Classifications 1 1 .3.3 Pavement Classifications 1 1 .3.4 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -1 1 1 -1 1 1 -2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -2 Design Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -4 1 1 .4.1 Appearance and Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -4 1 1 .4.2 Vis u a l Task 1 1 .4.3 I ntegration with Non-lighting Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 .4.4 Vertical Surface I l lu m i nation 1 1 .4.5 Glare, Light Trespass, and Sky G l ow Issues 1 1 .4.6 I m pact of Head l i g hts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -4 1 1 -5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -5 1 1 .5 1 1 .6 1 1 .4.7 I m pact of Trees on Lighting 1 1 .4.8 Spectral Considerations 1 1 .8 1 1 -5 1 1 -5 Design Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -5 1 1 .5.1 Cu rves and Steep Grades 1 1 .5.2 Trees Adjacent to Roadway 1 1 .5.3 Location Considerations 1 1 .5.4 Safety and Security 1 1 -5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -6 Lighting Recom mendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -6 . 1 1 .6.1 1 1 .7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Streets - General Recommendations . . . . . . 1 1 -6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 .6.2 Pedestrian Wal kways and Bikeways - General Recommendations 1 1 .6.3 Lighting Criteria 1 1 .6.4 An Alternative Method for Determining Lighting C riteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -7 1 1 -8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Design Calcu lations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -9 1 1 .7.1 Recommended Calculation Methods 1 1 .7.2 Recommended Luminance Calculation Method for Streets 1 1 .7.3 Recommended l l l u minance Calculation Method for Walkways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -9 1 1 .7.4 Recommended l l lu minanceCalculation Method for Cul-de-Sacs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -9 1 1 -9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Design Exa mple - A Major (Arterial) Street . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -9 Additional Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References for Chapter 1 1 . . . . . . . . • . . . • . . . . . . . . . . . . . . . . . . . . . . • . . . . . • . . . • . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -1 2 1 1 -1 3 Chapter 1 2: I ntersections, Roundabouts, a n d Crosswalks 1 2.1 1 2.2 1 2.3 1 2.4 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2-1 1 2.1 .1 Land Use Definitions 1 2.1 .2 I ntersection Definitions 1 2-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2.1 .3 Pedestrian Activity Definitions 1 2.1 .4 Lighting Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2-2 Design Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2-3 1 2.2.1 Safety 1 2.2.2 Site Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2.2.3 Desig n Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2.2.4 Identification of Design Elements 1 2.2.5 Spectral Considerations 1 2-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2-3 1 2-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2-3 I ntersections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2-3 1 2.3.1 I ntersection Design Issues 1 2.3.2 Intersection Lighting Req uirements Roundabouts 1 2-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-8 1 2.4.1 Key Di mensions and Categories 1 2.4.2 Roundabout Traffic Operations 1 2.4.3 Desi g n Considerations for Roundabouts 1 2.4.4 Lighting Recom mendations for Roundabouts 1 2.4.5 Roundabout Calcu lation Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2-9 1 2-1 0 1 2-1 2 1 2-1 3 1 2-1 4 1 2.5 Crosswalks at I ntersections 1 2.6 Midblock Crosswalks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2-1 8 1 2.6.1 Supportive Research . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2-1 7 1 2-1 8 1 2.6.2 Design Considerations for Mid block Crosswalks 1 2.6.3 Mid block Crosswalk Design Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2-20 1 2-1 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2.6.4 Lighting Recommendations for Mid block Crosswa l ks 1 2.6.5 Design Calcu lations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2-20 1 2.6.6 Mid block Crosswalk Design Exa mple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2-21 References for Chapter 12 1 2-20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-23 Chapter 1 3: At-Grade Railway Crossings 1 3.1 1 3.2 Design Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3-1 1 3.1 .1 General Considerations 1 3.1 .2 The Purpose of Rai lway Crossing I l l u m i nation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3-1 1 3.1 .3 Pole and Luminaire Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3-1 Design Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3-2 1 3.2.1 Coordination With Other Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3-2 1 3.2.2 Clear Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3-2 1 3.2.3 Obtrusive Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3-2 1 3.3 Lighting Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3-2 1 3.4 Lighting Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3-3 1 3.4.1 Horizonta l Calculations for the Railway Crossing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3-3 1 3.4.2 Vertical II l u minance Calculations for the Trai n Cars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3-3 1 3.4.3 Glare Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3-3 1 3.4.4 Calculation Grids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3-3 1 3.5 At-Grade Railway Crossing Design Exam ple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3-4 References for Chapter 13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3-6 Chapter 14: Tunnel Lighting 1 4.1 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-1 1 4.1 .1 Types of Tunnels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-1 1 4.1 .2 Tu nnel Topology Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-1 1 4.2 Tu nnel Design Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-3 1 4.2.1 Traffic and Roadway Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-3 1 4.2.2 Tu nnel Architecture and Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-4 1 4.2.3 Visibility and Adaptation for the Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-6 1 4.2.4 Ease of Mai ntenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-6 1 4.3 Tu nnel Design Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-6 1 4.3.1 Daytime Adaptation at the Tunnel Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-6 1 4.3.2 Nighttime Adaptation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-9 1 4.4 Tu nnel Lighting Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-9 1 4.4.1 General 1 4.4.2 Daytime Pavement Lumina nce . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-9 1 4.4.3 Nig httime Pavement Lum ina nce . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-1 0 1 4.4.4 Non-roadway Surface I ll u m ination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-9 . 1 4-1 1 1 4.4.S Cu rved Tu nnels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-1 1 1 4.4.6 U niformity Ratios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-1 2 1 4.4.7 Veiling Lumina nce Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-1 2 1 4.4.8 Flicker Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-1 2 1 4.4.9 Tunnel Lighting Operation Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-13 1 4.4.1 0 Tu nnel Emergency Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-1 3 1 4.4.1 1 Lighting for Wayfi nding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-1 3 1 4.5 Light Application Techniq ues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-1 3 1 4.S.1 Symmetrical Light Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-1 3 1 4.S.2 Asymmetrical Light Distribution - Negative Contrast (ALD-NC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-1 3 1 4.S.3 Asymmetrical Light Distribution - Positive Contrast (ALD-PC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-1 4 1 4.S.4 Wide and Na rrow Tu n nels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-14 1 4.6 Tu nnel Calcu lations: Methods of Determination of Lumi nance Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-14 1 4.7 1 4.8 1 4.9 1 4.6.1 Lu m inance Val ues in Threshold Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-14 1 4.6.2 Threshold and Transition Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-18 1 4.6.3 Tu nnel Interior Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-1 9 Lighting and Electrical Equipment for Tu nnels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-19 1 4.7.1 Light Sou rces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-1 9 1 4.7.2 Equipment and Luminaires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-21 1 4.7.3 Tu nnel Physica l Conditions and Related Lum i na i re Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-21 1 4.7.4 Electric Power Supply and Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-22 1 4.7.S Measurement, Control, and Switching Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-22 Maintenance Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-23 1 4.8.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-23 1 4.8.2 Other Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-23 Calcu lation Example: Lseq Method for Determining Lth • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 14-24 References For Chapter 1 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-26 Chapter 1 5: Toll Plazas 1 5.1 1 5.2 1 5.3 The Plaza Defined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5-1 1 S.1 .1 Tol l Roads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 S-1 1 S.1 .2 Tol l Plazas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 S-1 1 S.1 .3 Approach Road (Ram p) and Depa rtu re Road . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 S -2 1 S.1 .4 Approach and Departure Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 S -2 1 S.1 .S Tol l Col lection Island . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 S -2 1 S.1 .6 I nfield 1 S.1 .7 Ad ministration and Mai ntenance Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 S-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 S-3 Design Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5-3 1 S.2.1 Current Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 S-3 1 S.2.2 Other Desig n Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 S-4 Design Issues . . . . . . . . . . . . . . . . . . • . . . • . . . . . . . . . . . . . . . . . . • . . . . . . . . . • . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5-6 1 S.3.1 Security Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 S-6 1 S.3.2 Lighting Zones and Com m u n ity Responsive Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 S-7 1 S.3.3 Obtrusive Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 S -7 1 5.4 Lighting Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-7 Additional Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-9 References for Chapter 1 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-9 Chapter 16: Off-Roadway Facilities 1 6.1 Public Rest and Service Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6-1 1 6.1 .1 Defi nitions 1 6.1 .2 Design Considerations 1 6.1 .3 Design Issues 1 6.1 .4 Lighting Recommendations 1 6-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6 -2 1 6 -2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6.2 Commercial-Vehicle Weigh Stations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6-4 1 6.2.1 Defi nitions 1 6.2.2 Design Considerations 1 6.2.3 Design Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6-5 1 6.2.4 Lighting Recommendations 1 6.2.5 Lighting Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6-6 1 6.3 Com mercial-Vehicle Chain-Up/Chain-Down Stations 1 6 . 3.1 1 6-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Design Considerations . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6-7 1 6.3.2 Lighting Recommendations 1 6.3.3 Lighting Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6-7 1 6.4 Accident Investigation Sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6-7 1 6 .4.1 Design Issues 1 6 .4.2 Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6-8 1 6.4.3 Lighting Recom mendations 16.4.4 Lighting Controls References for Chapter 16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6-9 . . . . . . . . . . . . . . . . . . . . . . Chapter 1 7: Parking Lots and Parking Garages 1 7.1 1 7.2 Pu rpose and Scope Definitions 1 7.3 General Considerations Com mon to All Parking Facilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7-2 1 7.4 1 7-1 1 7-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . • . . . . . . . . . . . . . . . . . . . . . . • . . . . . • . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . • . 1 7.3.1 Metrics 1 7.3.2 Vision Considerations 1 7.3.3 Site Considerations 1 7.3.4 L u minaire and Light Sou rce Considerations 1 7.3.5 Lighting Qua lity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7-4 1 7-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7-7 Parking Lots and Top (Open) Parking Decks of Garages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7-7 1 7.4.1 Desig n Considerations for Parking Lots 1 7.4.2 Desig n Issues for Parking Lots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7-8 1 7.4.3 Lighting Recommendations 1 7.4.4 Lighting Equ ipment for Parking Lots 1 7.4.5 Lighting Controls 1 7.4.6 Maintenance of Parking Lot Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7-9 1 7-1 2 1 7-1 2 1 7.5 Parking Garages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7-1 2 1 7.5.1 Design Considerations for Parking Garages 1 7.5.2 Design Issues for Parking Garages 1 7.5.3 Lighting Recommendations 1 7-1 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7-16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7.5.4 Lighting Equipment for Parking Garages 1 7.5.5 Lighting Controls 1 7.5.6 Mai ntenance of Parking Garage Lighting References for Chapter 17 1 7-1 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7-1 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7-1 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7-1 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7-21 Chapter 1 8: Roadway Sign Lighting 18.1 Sign Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8.1 .1 Static Signs 1 8.1 .2 Signs With Variable or Changeable Messages 1 8.1 .3 Mounting Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8-1 1 8-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8-2 18.2 Sign Lighting Economics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8-2 18.3 18.4 External Sign Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8.3.1 Eq u ipment 1 8.3.2 Lighting Design for Externally I l l u m i nated Signs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8-2 1 8-2 1 8-3 Internal Sign Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8-4 1 8.4.1 Eq u ipment 1 8.4.2 Design of Internally I lluminated Signs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8-4 18.5 LED Message Signs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8-4 References for Chapter 18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18-5 Chapter 19: Temporary and Work Zone Lighting 19.1 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-1 1 9.1 .1 Work Zone Categories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-1 1 9.1 .2 Work Zone Lighting Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-1 19.2 Design Considerations 1 9.3 Design Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-2 1 9.4 1 9.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-2 1 9.3.1 G l a re 1 9.3.2 Tra nsient Adaptation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lighting Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-2 1 9-3 1 9.4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-3 1 9.4.2 Avoiding Glare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9.4.3 Limiting Vertical II l u m i nance at the Driver's Eye 1 9.4.4 Provid ing Transition Lighting 1 9.4.5 Recommendations for Rural Hig hways With Long- D u ration Work Zones 1 9.4.6 Recommendations for Freeways With Long-Duration Work Zones 1 9.4.7 Recommendations for U rban Surface Streets With Street Lighting and Long-Duration Work Zones 1 9-6 1 9.4.8 Lighting for Flagging Stations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-5 . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-6 Equipment Guideli nes for Work Area Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-7 1 9.5.1 Orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-7 1 9.6 1 9.5.2 Mounting Height . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-7 1 9.5.3 Vehicle Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-7 Operational Constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-7 1 9.6.1 Light Trespass and G lare Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-8 1 9.6.2 Enforcement Plan and Field Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-8 Additional Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9-9 References for Chapter 19 1 9-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Annexes Annex A - Street, Highway, Tunnel, and Parking Area Field Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1 Annex B - Outdoor Lighting Controls: Additional I nformation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1 Annex C - Contrast Method for Determining Threshold Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1 Annex D - Calcu lation of Tunnel Wall Luminance Using BRDFs for Typical Tun nel Wal l Materials . . . . . . . . . . . . . . . D-1 Annex E - Eval uation of Lseq: Correct Use of a Camera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-1 Annex F - Conversion Factors, Acronyms and Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-1 Annex G - Visibility-Based Analysis of Parking Facility Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-1 Annex H - General Procedure for Ca lculating Maintained l l l umina nce in Parking Lots and Garages . . . . . . . . . . . . H-1 Annex I - Environmental Ratings for Enclosures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 Annex J - Roadway Lighting Operations and Maintenance Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .J-1 Annex K - Alternative Lighting Criteria Selection Methodology K-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Glossary Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GL-1 I ntrod uction to This Reco m me n ded Practice This Recommended Practice is a compilation of l ig hting design techniques and criteria, a l l offered for q u a l ity roadway l ighting sol utions. Each chapter should not be taken in isolation but used as a whole for quality lighting design for roadways and other environments where vehicles are present, such as tu nnels, intersections, and parking lots. A l i g hting designer will often simplify the design criteria to l i g hting level and u niformity. However, i m pacts on visual quality go beyond these simple criteria and encompass m i n i mizing g la re and providing spectral contrast on pedestrians, hazards, and other vehicles. All design criteria are i mportant i n order to achieve these goals: 1 . Improve motorist visual q u a l ity 2. Provide quality light and increased contrast for seeing hazards 3. I l l u m inate conflict areas 4. M i n i mize environmental i m pacts of light at night 5. Employ lighting systems that a re easily maintai ned and m i n i mize energy use This docu ment was prepared with the objective of provid ing l ig hting design guidance for most kinds of roadway and roadway-related applications. The recommendations contai ned i n this document, however, may not reflect specific loca l factors or situations that a re not typical and req u ire special treatment. The contents of this Standard are based u pon consensus of roadway l i g hting experts. It has no legislative a uthority unless adopted by an a uthority having j u risdiction. This Recommended Practice is not intended to esta blish a basis for civil liability. This document is i ntended to be a single sou rce of reference for roadway lighting; however, additional documents such as electric codes, transportation design g u ides and other codes and sta ndards are often req u i red design references. H istory of the Document This Recom mended Practice is a compilation by the IES staff and the Roadway Lighting Comm ittee's Special Task G ro u p of efforts from several l ighting organizations and authorities and was first publ ished i n 201 8. This docu ment u pdates the 201 8 version. The majority of the topics covered are from 1 2 previously separate roadway lighting docu ments of the I l l u m i nating Engineering Society, along with the Transportation Association of Canada (TAC) Guide for the Design of Roadway Lighting, and the TAC Roadway Lighting Efficiency & Power Reduction Guide. D u ring the review and compilation, the Roadway Lighting Comm ittee revisited practices on design, i n stallation and maintenance methods of roadway l ig hting systems. The team i ncorporated new or revised methodolog ies, design concepts and procedu res, and included advancements i n international research on l i g hting con cepts. In preparing this docu ment the team sou rced standards from a round the world and applied the most applicable proven practices. It is important to note that new in novative design methods and products are being developed and will affect the future of roadway l i g hting. Some of these new design concepts and products are touched on i n this document. Because m u c h change i s anticipated i n the roadway design and technology, it is the responsibility of l ighting desig ners and administrators to stay current with new tech nolog ies and concepts. ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities How to Use This Recommended Practice This Recommended Practice may be used as a basis for the design and insta l lation of roadway l ighting and associated systems. This can be acco mplished by selecting the a ppropriate sections and following the recommended procedu res, including applying the recommended criteria. The docu ment presents criteria that are recommendations derived through a n American National Standards I nstitute (ANSI) consensus process. It may a lso be used as a basis for understanding roadway l i g hting desi g n, as wel l as the underlying theories and criteria for reviewing designs. Fundamental information upon which roadway l ighting designs a re based is provided in Part 1 - Fundamentals. This i ncludes information on lighting theory, calcu lations, obtrusive light, the design process, system components, standards and codes, the use of computer software in roadway l ig hting design, and maintenance and operations. Part 2 - Design appl ies the principles and i nformation presented in Part 1 to specific circumstances that may benefit from roadway lighting. Lig hted facil ities may include roadways, interchanges, i ntersections, tunnels, and toll plazas. Off-roadway facilities are a lso i ncl uded, such as pedestrian and bicycle pathways that are adjacent to the right of way, weigh scales, rest a reas, and roadway signs. Each chapter of Part 2 - Design is related to a particular type of roadway application and is arranged in a consistent fashion to a l l ow the reader to easily assi milate new material. Design exa m ples a nd, where applicable, step-by-step na rratives are presented to assist the reader in understanding the design process. In addition to the Ta ble of Contents at the beg i n n i ng of this document, each chapter has its own Table of Contents. The a n nexes at the end of the document contai n supplementa l information of i nterest to lighting professionals. A Glossary of roadway-related lighting terms fol l ows the a nnexes. References are provided at the end of each chapter and a n nex as applicable. II Part 1 - Fundamentals I ntrod uction to Roadway Lig hti ng Cha pter 1 CO N T E N TS 1 .1 1 .2 Why Light? 1 -1 H u man Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 -1 1 .4 1 .3 The Value of Lighting . . . . . . . . . . . . . . . . . . . . . . 1 -2 1 .6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 .3 . 1 The Key Benefit A Red uction In Crashes . . . . . . . . . . . . . . 1 -3 1 .3.2 1 .3.3 1 .5 1 .7 1 .8 Lighting Warrants 1 -5 Energy Conservation . . . . . . . . . . . . . . . . . . . . . . 1 -5 . . . . . . . . . . . . . . . . . . . . . . . . . Environmental Factors . . . . . . . . . . . . . . . . . . . . . 1 -5 Alternatives to Lighting 1 -6 Reference Lighting Organizations 1 -7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cost-Benefit Analysis of Roadway Lighting . . . . . . . . . . . . . . . . 1 -4 Add itional Reading The Need for Good Design . . . . . . . . . . 1 -4 References for Chapter 1 . . . . . . . . . . . . . . . . . . . . . . . . . 1 -9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 -8 I ntroduction to Roadway Lighting I ntrod uction to Roadway Lig hti n g D Chapter 1 riving at night is a necessity in o u r modern, 24-hour society. As a result, roadway lighting has also become a modern real ity. The main pu rpose for lighting roadways and other transportation related facilities is to provide a n enha nced visual enviro n m ent for people to safely use the road system d uring hours of darkness. An enhanced visual environment red uces motor vehicle col lisions and provides a safer environ ment for pedestrians, cyclists, and drivers.1•2•3 In providing some knowledge of what lies ahead on the road, l ighting also provides a level of psychological comfort for those using roadways. 1 .1 Why Light? secu rity is of pa rtic u l a r concern, the reader is Collision statistics gathered throughout North America referred to /ES G-7- 76, Security Lighting for People, show that more than 50% of fatal collisions happen Property, and Critical Infrastructure. during nighttime hours. Even though a n estimated 25% • of travel takes place d u ring these hours, the fatality rate Economics: Lig hti ng may d raw peop l e into a commercial a rea by providing increased visibil ity of is three times higher than during daytime hours. Properly businesses and a sense of personal security, and may designed roadway l ighting aids in im proving visibility of thereby lead to an increase in commerce. Decorative roadway features and helps the road user locate objects l i g hting can be used for the economic revital ization on the roadway as wel l as other vehicles, pedestrians, a nd of a n area by contributing to a "sense of place" or cyclists. This results in i ncreased safety for all.2 by supporting a commun ity a rchitectural or u rban design theme. Note: The benefits l isted a bove may There is a consensus of statistics indicating that roadway not necessarily apply to residential roads where lighting substantial ly decreases nighttime collision rates. there is l ittle or no pedestrian activity d uring the Most im portant, the number of fatalities is reduced. hours of darkness. Pedestrian fatalities account for approximately one quarter • Aesthetics: L i g hting may d raw attention to of all roadway related fatalities; hence, lighting of urban architecture and other aesthetic features such as areas with large numbers of pedestrians is also important.4•5 streetscapes, monuments, or parks. These featu res can enha nce the nightti me use of facil ities and Lighting of roadways and other transportation faci l ities improve the experience of roadway users at may have a n u m ber of benefits not directly related to adjacent locations. d riving. These include: • Personal security: Although there is some This Recommended Practice is intended to recommend controversy i m p roves proper tech niques to a l low motorists, pedestrians and secu rity, there is no q u estion that i ndividuals feel cyclists within the right of way to benefit from the more secure when walking, cycling or d riving in a va l u e of l ighting. If designed or insta l l ed improperly, wel l-lig hted a rea. Though some studies have shown the benefits of l i g hting may be reduced. I mproper pole that adding luminaires or i ncreasing light l evels heig hts may lead to excessive spi l l l ig ht on adjacent over whether l i g ht i n g can reduce cri me in a given a rea, the actual long­ properties. Poles placed within the clear zone without term benefits and com m u n ity-wide i m pacts are brea kaway bases may pose safety concerns. Over­ u n known.6 By creating a safe feeling, l ig hting may l ig hting may reduce visi bil ity while consu ming excessive d raw people i nto an area, and increased pedestrian a m o u nts of energy. circulation will typica l ly i m prove secu rity. Social and economic factors of a g iven a rea, as wel l as police presence, will also have i m pacts on personal 1 .2 H u ma n Factors secu rity. Note: For non-rig ht-of-way areas where The human factors associated with l i g hting, including 1 -1 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities physical and psychological aspects, are complex. For As the eye ages, less light reaches the retina, and roadway l i g hting, some of these i nclude the condition more of the l i g ht that enters the eye is scattered. of the d river's eyes, the constantly changing level of eye These changes cause reduced contrast sensitivity and adaptation, the d river's level of fatigue, and his or her increased sensitivity to g la re. The U.S. Nationa l Hig hway sensitivity to l i g ht. Transportation Safety Association (NHTSA) reports that, between the ages of 20 and 70 years, aging directly Visual cues are estimated to comprise about 90 percent red u ces contrast sensitivity by a factor of about three. of a d river's i nformation, including critical information This results in a reduced abi lity of older d rivers to adapt on lateral control of the vehicle, estimation of gaps, to l ower l u m i na nce levels. In addition, the magnitude of detection of haza rds, and estimation of speed. At the the "g lare factor" (referring to glare sensitivity and glare same time, visibility for the driver is reduced at night. recovery for an i nd ivid ual) is a bout twice as g reat for For a typical d river with 20/20 dayti me vision, vision is a 70-year-old d river as for a 20-year-old d river.a Other reduced to 20/25 or 20/30 at night. For older d rivers, researchers report that about one-third the a mount visibi l ity is further reduced. The nighttime vision of a of l ig ht penetrates the eye of a 60-year-old compared 70-year-old with 20/20 daytime vision is typical ly 20/40 to that of a 20-year-old. This is due to increased lens or worse. density, yel lowing of the lens, a nd, to a lesser extent, Drivers may a lso be affected by "n ight myopia," that is, a p pear darker to an older person. These characteristics a d ifficu lty focusing on the roadway ahead. When the of older people indicate that roadway i ll u m i nation is visual field has little sti mulation (such as on a n u n l i g hted especially i mportant for that age g roup, particularly rura l road), a d river tends to focus on a point a bout 1 where the n u m ber of veh icles is i ncreased around to 2 meters ahead of the vehicle. As a result, objects more-complex i ntersections. reduced pupil size.a As a result, at night a l l visua l sti m u li on other portions of the roadway a re outside the central field of view and consequently may be m issed. Older people a re also more susceptible to physical The d river's eyes a lso req u i re time to adapt to the conditions dark when leaving a brig htly lig hted a rea, particu larly peripheral vision, and macular degeneration results in the absence of transitional l i g hting. Age and the in the loss of centra l vision. O lder people are more that affect vision. Glaucoma red uces consumption of a lcohol can also adversely affect the l i kely to have cataracts, which reduce l i g ht tra nsmission eyes' abil ity to recover from excessive glare.7 through the lens and affect light scatter, leading to glare sensitivity.a At nig ht, the contrast between an object and its background can be d ra matica lly reduced, affecting the Though it is generally u nderstood that aged i nd ividuals road user's abil ity to see objects on the road. Age and need more light to see, there is m i n i m a l research alcohol consumption can both adversely affect contrast ava ilable that defines l ighting levels appropriate for sensitivity. Fatigue, which is common d uring nighttime older road users. The i l l u m i nance and l u m i na nce design d riving, also reduces the a b i l ity of road users to detect criteria recommended i n this Recommended Practice objects and react to them. use data without age-dependence criteria, a method As a person ages, vision is reduced. Researchers note that of s m a l l target visibil ity (STV), however, does acco u nt that has been verified thro u g h consensus. Calculation cha nges to the eye from about the age of 40 years lead for d river age, using a 60-year-old observer with normal to reductions in visua l acuity and contrast sensitivity. Eye eyesight whose fixation time i s 0.2 seconds. (See movements i n older road users a re slower, more time is Chapter 3 for calculation methods.) required to change focus, sensitivity to glare increases, and the time taken to recover from glare increases. Researchers have also noted that, in addition to having 1 .3 The Value of Lighting diminished visua l a b i lity, older d rivers genera l ly require Roadway l i g hting, if properly designed and installed, a longer time to process i nformation.a should reduce coll isions, improve safety for cyclists and 1 -2 I ntroduction to Roadway Lighting pedestrians, and i m prove personal security by i m p roving A 2001 Canadian study compared the safety benefits visibi l ity. The benefits to owners and the public can be of fu l l and partial interchange l i g hting.12 The study demonstrated u nder certai n circumsta nces by financial exa m ined fata l, inju ry, and property-only col lisions i n and environmental eva l u ation. (See also Section 1 .7 t h e Province o f Quebec. T h e authors o f t h e study Alternatives to Lighting). It is important to note that concluded that l ig hting of freeways and hig hways is an a lot of research exists and is ongoing as to the value of effective design tech nique that sign ificantly reduces l ighting. It is up to the ju risdiction or desig ner to source the risk of nighttime col lisions. The study noted that out research and information to make an informed a l t h o u g h fu l l i ntercha nge l i g hting did not bring a decision as to the value of l ig hting for a particu lar significant reduction in injuries or fata l ities, there was a project. 43% red uction in property-da mage-only col lisions. This is compared to a 35% reduction i n property-damage­ 1 .3.1 The Key Benefit - A Reduction in Crashes. only col l isions for partial intercha nge l ig hting. Red uction i n the n u m ber and severity of crashes, including collisions, is a key benefit of roadway l ig hting. The benefits ach ieved thro u g h the i nsta l lation of roadway lighting vary depending on the type of roadway and area. For u rban a rterial and collector roadways, the benefits include a red uction in vehicle crashes as well as a red uction i n pedestrian and cyclist injuries and fata l ities. Lighting these roadways i mproves vehicle, pedestrian and cyclist visibility, and as such, should aid in red uction of crashes and fatal ities. Red uctions of 45% to 80% in pedestrian fatalities, as wel l as reductions of 2 1 % to 36% in all types of collisions, have been fou nd when fixed roadway l i g hting is added in these roadway classifications.9 It is im portant to note the majority of the stud ies and research to su pports is based on arterial, col lector, freeway and hig hway classifications. Lighting on local residential roads wil l typica lly have less benefit than on higher-speed and higher-traffic-volume collectors and arterial roads, and vehicle headlamps sho u l d provide d rivers with the req u i red visibility with the safe stopping d istance (SSD).1 0 A U .S. Federal H i g hway Ad min istration (FHWA) report13 describes research conducted in 1 98214 and concludes that com plete interchange l ig hting (CIL) is preferred to partial intercha nge lighting (PI L), but that PIL is better than no lighting at an interchange. The nig ht-to-day col l ision ratio is a key factor in assessing the value of roadway lighting. The higher the ratio, the more value the lighting provides. The Reg ion of Waterloo, Ontario, Canada tracked coll isions on regional roads from 1 999 to 2003.15 A s u m ma ry of collision data provided by the Region showed that for mid block parts of roads, the nig ht-to­ day coll ision ratio without l ig hting was 0.65:1 . The ratio with l i g hting was 0.26:1 , a reduction of 60 percent. This was based on nearly 1 0,000 coll isions on roads with lighting and 3,500 without l ighting. At stop-controlled i ntersections, they found the nig ht-to-day collision ratios to be similar for l i g hted and u n lighted cond itions (u nder 0.3:1). This was based on fewer tha n 3,800 coll isions at intersections with lighting and 700 col l isions Lighting on freeways and hig hways will have less benefit in intersections without l i g hting. I l l u mination levels and in terms of reducing pedestrian and cyclist i nj u ries and un iformities at intersections were not provided with fatalities because such facilities a re rarely designed for this information. Therefore, it is u n known to what l evel pedestrian and cyclist traffic. Roadway l i g hting provides of i l l u m ination or u niformity the intersections were greater benefit on hig hways and freeways with complex designed. geometries and high vol u mes of traffic, such as i n u rban areas, than on those with simple geometries a n d The net value of lighting includes evaluation of system less traffic, such as i n rural areas. Overa ll, nig ht-to-day costs, as described in Section 1 .3.2. coll ision ratios tend to be lower on freeways with fixed l ighting than those without. Red uctions in col lisions The installation of l ighting in areas with high nighttime of u p to 40% d u ring hours of darkness have been collision rates should be a key consideration. However, predicted because of fixed roadway lighting.11 the use of pavement markings with high retro-reflective 1 -3 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities roadside to the a ntici pated red uction of costs from reduced delineators can be a cost-effective alternative to lighting crashes, based on the best available data. The exact properties, i n-pavement reflectors, and on freeways and highways in rural areas (see Section 1 .7 relationship between street l ig hting and accident rates Alternatives to Lighting). It is critical that decision makers is complicated beca use there are many factors affecting analyze collision data, determine the specific nature of the visib i l ity, but the clear causal relationship between l ig ht problem, and then apply the most cost-effective solution. a n d visibi l ity shows that there is a relationship. It sho u l d be noted that in 1 974 the California Department 1 .3.3 The Need for Good Design. The safety benefits of Transportation (CalTrans) removed roadway lighting gai ned throu gh i m proved visibility due to roadway from lim ited-access hig hways and adopted a policy not l ig hting can be somewhat negated if poles a re placed to l i g ht these roads except where a section of roadway within the c lear zone* or in areas where they are subject was determi ned to be a "proven point of conflict." to i m pact from vehicles. (Refer to the AASHTO Roadside CalTrans has used roadway l ig hting o n ly as a last resort, Design Guide [U.S.] or the TAC Geometric Design Guide and o n ly when passive alternatives fai led to achieve the [Canada] for further information on the clear zone.) necessary reduction i n collisions. Even when CalTra ns authorized lighting, it was l i m ited to installations only Proper pole placement will d ramatically reduce the for the specific section of road where a proven point of potential for a vehicle stri king a l ig ht pole. Breakaway conflict was determined. This CalTra ns policy remains devices a re designed to reduce damage to vehicles in effect today, more than 40 years after it was first and property as wel l as inj u ries to vehicle occupants. adopted. It should be noted that there has not been a ny H owever, breakaway devices should not be used where analysis done on crash reductions or i ncreases in the pedestrians may be present. u n lit sections of Ca l ifornia freeways. There is little evidence that increasing lighting beyond the 1 .3.2 Cost-Benefit Analysis of Roadway Lighting. levels defined in this document will have significant benefit. Va l u e can often be esta bl ished by a cost-benefit While initial lighting may be brighter than the design end­ a n a lysis. Cost-benefit analyses of roadway l i g hting of-life levels (see Section 3.1.6 Light Loss Factors), light installations a re com plex because of the many varia bles levels should not significantly exceed the recommended that need to be considered. These variables include the values without j ustification. More light is not a lways cost of the l ig hting instal lation and its operation and correlated with better visibility, as inappropriately designed mai ntenance; the reduction i n the nu m ber of collisions; lighting can increase visibility-reducing factors such as glare the actual monetary val u e of those col lisions; and the and can increase obtrusive light (see Chapter 4). consideration of other factors that influence col l ision frequency and severity, such as road geometry, weather, road user ability and i m pa i rment, vehicle conditions, and roadway obstructions. Studies u n derta ken t h ro u g h o u t i n c l u d e roadway l i g hting, vehicle l i g hting, signa ls, the world have analyzed the effects of l ig hting with respect to its effect on col l isions. In most cases, the resu lts a re positive, showing a reduction in the nu mber of col l isions and fata l ities when l i g hting is insta l led. Because of the many variables, it has not been possible to defin itively identify a percentage reduction in coll isions (the major benefit of lighting) that is d i rectly attri butable to l ighting. The val u e in performing a cost-benefit eva l uation l ies in the qua ntification of costs of system s compared 1 -4 Roadway visibil ity at night is affected by a complex assem b ly of components with many elements. These signage, and pavement markings, as wel l as the level of a m bient l ight from su rrou nding development. These elements, working and interacting together, provide visibility and information to the roadway user. * A clear zone is an unobstructed, transversa ble roadside area that a l lows a driver to stop safely, or regain control of a vehicle that has left the roadway. The width of the clear zone should be based on risk (also called exposure). Key factors in assessing risk include traffic volumes, speeds, and slopes. Clear roadsides consider both fixed objects and terrain that may cause vehicles to roll over. U.S. Federal Highway Administration (FHWA), Safety web page ( htt ps ://safety. fhw a .dot.g ov/roadwa y_ d e pt/co u nter m ea su res/ safe_recovery/clear_zones/). I ntroduction to Roadway Lighting 1 .4 Lighting Warrants The sensitivity to energy conservation is a g lobal trend Because l i g hting can be a va l ua ble means for i m p rovi ng not lim ited to the lighting ind ustry. Withi n the industry, safety for those using roads, it is i mportant to apply more energy-efficient l i g ht sources and innovative l ighting where it can provide the best va l ue (see Sections control systems are being developed to red uce energy 1 .3.1 through 1 .3.3). Since the ownership of roadway demand. Designers a re encouraged to research and l ighting usua lly rests with a governm ental authority or recommend new technologies that are a i med at util ity, and because budget constraints allow l ittle room red u cing energy consumption with quality designs that for u nnecessary expenditure, economic conditions w i l l red u ce g la re. obviously play a major role in t h e design o f a lighting system . Budget considerations may mean that it is not practical to light a l l roads. A warrant system can help 1 .6 Environmental Factors to define and prioritize a reas that will typica l ly benefit Lighting has i m pacts on a n i m a l com m u n ities, from most from lighting. (Refer to the U.S. FHWA Lighting insects to large predators. Depending on the species, Hand book for fu rther information on warranting.) it can enable or disrupt normal breed i ng; predation or Lighting is only one of several possible measures to address nig httime visi b i l ity needs (see Section 1 .7 Alternatives to Lighting). Applicability of these measures sho u ld be considered when weighing the need for lighting. The designer should a lso be aware that l ighting ca n n ot rectify su bsta ndard geometric desig n. predator avoidance; m i g ration; feeding; and com m u n ication a nd social interactions-in short, every aspect of animal l ife. Plant photoreceptors a l l ow the plant to measu re and respond to five para meters of the lit e nvironment: l i g ht qua ntity, spectru m, d i rectionality, timing and duration. Plants that a re sensitive to photo­ periodicity in their flowering, bud dormancy, or leaf senescence may be adversely affected by prolonged l i g ht. They need sunlight during the day and darkness at n i g ht to susta in a healthful life. Light pollution, sky glow, a n d obtrusive light a re terms used to describe excess 1 .5 Energy Conservation Roadway l i g hting has va l u e and can i m prove road user safety; however, issues such as life-cycle cost and the environmental i m pact of energy use req u i re that l ighting decisions also consider optimization of energy use. roadway lighting i nclude: Avoid over-lighting roadways. More light is not necessarily better, as d iscussed in Section 1 .3.3 The Need for Good Design. Some a reas are restricting the a mount of wattage that can be used in a g iven area. (Refer to Chapter 4 - Obtrusive Light for a fu ll d iscussion.) • considerations whenever a new outdoor l ig hting design is being prepared. As people i ncreasingly appreciate the bea uty and benefits of the night, they become less tolerant of u nnecessary and i ntrusive l ighting. Key recom mendations for energy conservation i n • or nu isance light created by humans. Light pollution a n d light trespass have become extremely im portant Electric l i g hting increases sky glow a bove the natura l backg round levels through a combi nation of di rect and reflected light. Any light em itted above the horizontal contributes d i rectly to sky glow. Light reflected from the ground or from vertica l surfaces can contribute to sky glow, depending on the g roundcover conditions. Short-wavelength l ig ht sou rces can improve human Select energy efficient l u m i n a i res. All roadway vision, but the increase i n short-wavelengths i ncreases l u m i n a i res the relative impact of Rayleigh scattering and thus can should m eet the perfo r m a n ce req u i rements noted in Section 6.4.2 Special lead to relatively higher sky glow. Solutions include Lighting selecting l u m i naires with a n u pl ig ht (U) BUG rating Luminaires. All l u m i na i res should be selected per l i g hting zone as outlined in the IES/IDA Model based on appropriate optical performance for the Lighting Ordinance (MLO) (see Section 2.6.3 Luminaire application. Classification System and BUG Ratings). Considerations for Roadway - 1 -5 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities The term light trespass relates to light that is obtrusive When roadway l i g hting is not present, n i g htti me offsite. A typica l example is the "light shining in my navigation genera l l y depends upon a road user's window" complaint. Solutions include shielding the abi l ity to see the roadway and pavement markings offending l u m inaire so that its brig htness is not directly via veh i c l e head l a m ps . Typica l pai nted pavem ent visible to the complainant, turning off or d i m the l ig ht after cu rfew, or in some cases e l i m inating the l ight sou rce if not req u ired . The offending i l l u m ination is called obtrusive light. ma rkings use g lass beads appl ied with the paint. The g lass beads, however, a re not highly retro-reflective. Retro-reflective markings a re desig ned to reflect more light back to a road user's eyes and thereby improve visibil ity compared to ordinary markings. The effective reflectivity of g lass beads is reduced in wet weather when they are covered by a fi l m of water. To address this 1 .7 Alternatives to Lighting problem, high-performa nce pavement markings have Scenarios may be encou ntered where it is not practical to been developed for both wet and d ry road cond itions. provide l ighting. Where l ighting is considered beneficial, The benefits of these wet-pavement markings over but there are practical challenges to installation, retro­ paint have been assessed by a report from the Virg i n ia reflective pavement markings, raised pavement ma rkers Tech Tra nsportation l nstitute.16 The report shows that (RPMs), and post-mou nted delineators (PM Ds) should be considered to aid i n a road user's navigation of the roadway. Some of these navigational aids are shown in Figure 1 -1 . at n ight the visibility to a d river in wet weather of paint with g lass beads is a pproximately 22.0, compared to 88.0 for wet retro-reflective tape markings. A more recent report was issued by the Virg i nia Department of Transportation stating that these wet-weather tape markings a re very effective at i mproving visibi l ity of the The i nformation noted below i s not intended to markings i n both wet and d ry weather.17 They are more recommend a substitute for l i g hting when the presence expensive to insta l l but last much longer than paint with of pedestrians or cyclists is involved. The alternatives g lass beads. Where l ighting cannot be supplied, retro­ presented wil l typically aid in g u ida nce for the road user reflective and wet-weather pavement markings should but will have little benefit for pedestrians and cyclists. be considered as an alternative to standard pai nted Retro-reflective pavement markings, RPMs, and PMDs may be considered as a lternatives to lighting for freeway a n d expressway applications where pedestrians a re not present, as they wi l l have no benefit in i mproving pedestrian visibil ity. markings. The use of raised pavement ma rkers (RPMs) may be considered as another alternative. RPMs usually consist of g lass beads or a ng led m irrors housed in a raised cera mic or plastic base. These markers can also provide effective nig httime delineation on wet pavement. Due to the relatively high installation cost, RPMs a re sometimes only insta l led to supplement conventional pavement markings at critical locations such as horizonta l cu rves. Conventiona l R PMs are often damaged or destroyed by snow removal equi pment. In locations that a re prone to heavy snowfall, RPMs may be set in recessed g rooves in the pavement. This i nstal lation method reduces the risk of damage from snow removal, but it a lso reduces the effectiveness of RPMs in wi nter conditions when Figure 1 -1 . Retro-reflective markings (diamond in the recesses may fi l l with snow and ice. As RPMs are foreground) and typical raised pavement markings often damaged by vehicles and equipment, regular (RPMs, next to lane markers). (Photo courtesy of 3M) mai ntenance is req u i red to replace damaged ma rkers. 1 -6 I ntroduction to Roadway Lighting Post-mou nted delineators (PM Ds) a re another effective actively method for provid ing roadway delineation at night. competence of organizations determining conforma nce PMDs consist of retro-reflective elements mou nted on to standards. ANSI provides accreditation for many IES posts approximately 1 .3 m a bove the pavement. They l ighting standards documents, including this document. engaged in accred itation-assessi n g the may be more effective than RPMs in winter conditions since they are located off the traveled way and a re less Federal Highway Administration (FHWA): The Federal l i kely to be damaged by snowplows. H i g hway Ad ministration (FHWA) is a n agency within the A com m o n cause of nightti me col l isions in isolated a n d local governments in the design, construction, and U.S. Department of Tra nsportation that supports state rura l areas is the presence of wild l ife on the road. An mai ntenance of the U.S. highway system. The Federa l effective method to deter wildlife from approaching H i g hway Administration is responsible for ensuring that the roadway is the use of wildlife reflectors. Roadside America's roads and highways continue to be among wildl ife reflectors are typically post-mou nted and act by the safest and most technologically sound in the world . reflecting l ig ht from veh icle head lights to form a series THE FHWA funds research that is documented i n a of lig hts visible to animals approaching the roadway. series of reports publ ished by the FHWA. The FHWA a lso Road authorities in N orth America have reported prepares and maintains a roadway lighting g u ide. varying levels of collision reduction after the installation Institute of Transportation Engineers (ITE): The of wildlife reflectors. Institute of Tra nsportation Engineers is a n international educational and scientific association that facil itates the 1 .8 Reference Lighting Organizations application of technology and scientific principles to This Recommended Practice covers the fu ndamentals research, planning, fu nctional design, implementation, of roadway l i g hting and is designed and written to be operation, policy development, and management for comprehensive i n this arena. There are, however, other any mode of g round transportation. ITE prepares and sources of lighting design i nformation that cover other m a i ntains e d u cational cou rses and i nformation for topics in more deta il, such as i nternational sta ndards, roadway lighting. warranting of l i g hting systems, and the i m pact of l ighting on the night sky. These organizations include: International Commission on Illumination (CIE): The International Comm ission on I l l u m ination-al so known American Association of State Highway as the CIE from its French title, Commission Internationale Transportation Officials (AASHTO): AASHTO is de / Ec/airage-is devoted to worldwide cooperation a representi ng and the exchange of information on a l l matters relating non profit, nonpartisan association ' hig hway and transportation departments i n the 50 to the science and art of l ig ht and lighting, color, vision, states, the District of Col u m b ia, a n d Puerto Rico. photobiology, and image technology. The CIE's Division AASHTO serves as a liaison between state departments 4 i s dedicated to l ighting for transportation. They of transportation a nd the federal government. AASHTO produce i nternational standards on roadway lighting, is an international leader in setting technica l standards sig nage, signals and l i g ht trespass. for all phases of highway system development. AASHTO reviews and prepares a Roadway Lighting Design G u ide International Dark-Sky Association (IDA): The I DA that is available for sale. was esta b lished as a nonprofit organization in 1 988 to mitigate or elimi nate the adverse i m pact of lighting on American National Standards Institute (ANSI): The the views of the darkened nighttime sky. Nearly every Institute oversees the creation, pro m u l gation a n d com m u n ity in North America has active members of the u s e o f thousands o f norms and g u ideli nes in nearly I DA among its population. With the help of the IES, I DA every sector: from acoustical devices to construction has prepared documents such as the Model Lighting equipment, from dairy and l ivestock production to Ordinance that provide guidance on the appl ication of e nergy d i stribution, and many more. ANSI is a lso l ighting in outdoor spaces. 1 -7 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Transportation Association of Canada (TAC): TAC is Transportation a not-for-profit, mem bershi p-based association that National Cooperative Highway Research Program Research Board (TRB) and the provides a for u m to exchange ideas and information (NCHRP): The U.S. Transportation Research Board (TRB) on technical g u idelines and best practices for Canadian provides innovative, research-based solutions to i mprove Roadway and Tra nsport. TAC provides roadway-related transportation. Part of the National Academies of Sciences, technical documents, best practices, and national Engineering, and Medicine, TRB is a nonprofit organization guidelines that are referenced across the country. In that provides independent, objective, and interdisciplinary particu lar, TAC provides the Guide for the Design of solutions. Through the NCHRP, they fund research and Roadway Lighting, 18 which was the source of some of the provide documentation of research, including several content i n this document. topics on roadway, sign, and vehicle lighting. A D D I T I O N A L R E AD I N G Note: This section is not part ofANS/I/ES RP-8-21. It is included for informational purposes only. CSA G roup. Canadian Electrical Code (241h ed). Ottawa, ON: CSA G roup; 201 8. (CSA C22). Federal Hig hway Adm i n istration. FHWA H ig hway Safety Engi neering Studies Proced u ra l Guide, 1 98 1 b. Washington, DC: National H i g hway I nstitute, Federal H i g hway Ad ministration; 1 98 1 . Gi bbs, M, Zein, S,Shaflik, C. I l l u m i nation of Isolated Rural Intersections. Ottawa: Transportation Association of Canada; 2001 . Tra nsportation Association of Canada. Geometric Design Guide for Canadian Roads. Ottawa: TAC; 1 999. Tra nsportation Association of Canada. Manua l of U n iform Traffic Control Devices for Canada (MUTCDC), Fou rth Edition. Ottawa: TAC; 1 998. Walton N, Rowan N. Warrants for H i g hway Lighting. Washi ngton, DC: National Cooperative Hig hway Research Program; 1 974. (NCHRP Report 1 52). 1 -8 I ntroduction to Roadway Lighting R E F E R E N C E S FOR CHAPTER 1 1. Keck ME. FHWA-SA-91 -0 1 9, The Relationship of Fixed and Vehicular Lighting to Accidents. Washington, DC: Federa l H i g hway Administration; Mar 1 991 . 2. Green ER. KTC-03-1 2/SPR247-021 F, Roadway Lighting and Driver Safety. Research Report. Lou isvi l le, KY: Kentucky Transportation Cabinet; May 2003. 3. Federa l H i g hway Ad ministration. FHWA-SA-96-040, FHWA Annual Report on Hig hway Safety I mprovement Programs. Washi ngton, DC: U.S. Dept of Tra nsportation; 1 996. 4. Wi l ken D, et al. FHWA-PL-01 -034, E u ropea n Road Lighting Technologies. Washington, DC: U.S. Department of Transportation; 2001 . 5. Lewin I, Box P, Stark D. FHWA-AZ-03-522, Roadway Lighting: An investigation and Eva l uation of Three Different Light Sou rces. Washington, DC: U.S. Department of Tra nsportation; May 2003. 6. Pai nter KA, Farrington DP. The Fina ncia l Benefits of Improved Street Lighting, Based on Crime Reduction. Institute of Criminology, University of Cambridge, U K; 2000 Aug. 7. Gupta N, Latta H, Ka u r A. Effect of g la re on night time driving in a lcoholic versus non-alcoholic professional d rivers. Int J Appl Basic Med Res. 201 2;2(2);1 28-1 3 1 . 8. I l l u m i nating Engineering Society. ANSI/I E S LS-7-20, Lighting Science: Vision - Eye a n d Brain. New York: I ES; 2020. 9. Joint Committee of the Institute of Traffic Engineers and the I l l u m inating Engineering Society. Public l ig hting needs. J Ilium Engr. 1 996;61 (9). 1 0. Roadway Lighting Efficiency & Power Red uction Guide. Tran sportation Association of Canada; 201 3. 1 1 . Box P. Relationship between i l l u m i nation and freeway accidents. J I l i u m Engr. 1 971 ;66(5). 1 2. Bruneau J, Morin D, Poul iot M. Hig hway Safety Design, Features and Evaluation; Safety of Motorway Lighting. Transportation Research Record Journal of Transportation. Washington, DC: National Academy Press; 2001 . (TRB No. 1 758). 1 3 . Federal H i ghway Ad ministration. FHWA-RD-01 -1 03, H i g hway Desig n Hand book for Older Drivers and Pedestrians; II. Interchanges (Grade Separation). Washington, DC: FHWA; May 2001 . 14. Janoff MS, Freedman M, Decina LE. NCH RP Report 256, Partial Lighting of I nterchanges. Washington, DC: National Cooperative H i g hway Research Program, Tra nsportation Research Board; 1 982. 1 5 . Ban ks D. Untitled spreadsheet of traffic data. Region of Waterloo, Onta rio, Canada; 2003. 1 6. Gibbons R, Hankey J, Pashaj I. Wet Pavement Visibility of Pavement Ma rki ngs, Executive Summary. Virg i n ia Technical and Tra nsportation Institute, Virg i nia Polytechnic I nstitute and State Un iversity; Oct 2004. 1 7. Research Synthesis Bibliography No. 20, Durable, Retroreflective Pavement Ma rki ngs & Markers I ncrease Visibi l ity for Drivers in Wet, N ight Conditions. Charl ottesvi l le, Virg.: Virginia Department of Tra nsportation; Jan 2009. http://vtrc.virgin iadot.org/rsb/rsb20.pdf. (Accessed 2021 Nov 4). 1 8. Transportation Association of Canada. Guide for the Desig n of Roadway Lig hti ng. Ottawa: TAC; 2006. 1 -9 Vision a n d Funda me nta l Concepts Cha pter 2 CO N T E N TS 2.1 2.2 2.3 Light and the Visible Spectrum . . . . . . . . . . . . . 2-1 Basic Principles of Vision . . . . . . . . . . . . . . . . . . . 2-2 2.2 . 1 Structure o f t h e Eye . . . . . . . . . . . . . . . . . 2-3 2.2.2 Function of the I ris and Pupil . . . . . . . . 2-3 Relative Photometry . . . . . . . . 2-1 7 2.5.5.2 Absolute Photometry . . . . . . . 2-1 7 Lumi naire Classification Systems . . . . . . . . . . 2-1 7 2.6.1 Longitudinal Lig ht 2.2.3 Function of the Lens . . . . . . . . . . . . . . . . 2-3 Distri bution (S, M, L) . . . . . . . . . . . . . . . . 2-1 9 2.2.4 Function of the Retina . . . . . . . . . . . . . . . 2-3 2.6. 1 . 1 S h o rt Distribution . . . . . . . . . . . 2-20 2.2.4. 1 P hotoreceptors . . . . . . . . . . . . . . 2-4 2.6. 1 .2 M ed i u m Distribution . . . . . . . . 2-20 2.2.4.2 P hotoreceptor Distribution . . . 2-4 2.6. 1 .3 Long Distribution . . . . . . . . . . . 2-20 2.2.5 Adaptation . . . . . . . . . . . . . . . . . . . . . . . . . 2-5 2.2.6 Accommodation . . . . . . . . . . . . . . . . . . . . 2-5 2.6.2 Visual Acuity . . . . . . . . . . . . . . . . . . . . . . . . 2-7 2.3.3 Glare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7 2.3.3.1 Disability G lare . . . . . . . . . . . . . . . 2-7 2.3.3.2 Disco mfort G lare . . . . . . . . . . . . . 2-7 L u m i n a i res at o r N e a r Center of Area . 2.6.2.2 . . . 2-20 L u m i naires on Near Side of Area . . . . . . . . . . . . 2-20 2.6.3 The IES Lu minaire C lassification System (LCS) and BUG Ratings . . . . . . . . . . . . . 2-2 1 Spectral Effects and Mesopic Vision . . 2-7 2.6.3 . 1 2.3.4.1 Limitations of the V('A) Cu rve . . 2-8 2.6.3.2 Solid A n g l e References . . . . . . 2-22 2.3.4.2 I m pacts on Roadway 2.6.3.3 Forward Light . . . . . . . . . . . . . . . 2-22 . . . . . . . . . 2-9 2.6.3.4 Back Light . . . . . . . . . . . . . . . . . . 2-23 Effects of Age on Vision . . . . . . . . . . . . . . 2-9 2.6.3.5 U p l i g ht . . . . . . . . . . . . . . . . . . . . . 2-24 Lighting Desig n 2.3.5 2.6.2.1 Contrast . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6 2.3.2 2.3.4 Transverse Light Distri bution (Types I - VS) . . . . . . . . . . 2-20 Visibility Fundamenta ls and Principles . . . . . . 2-5 2.3. 1 2.4 2.5 2.6 2.5.5.1 . . . . . Inte n d ed U s e . . . . . . . . . . . . . . . 2-2 1 Light Sou rces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 0 2.6.3.6 Bug Rati ngs . . . . . . . . . . . . . . . . . 2-24 Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 0 2.6.3.7 S u m mary . . . . . . . . . . . . . . . . . . . 2-24 2.5 . 1 2.5.2 Measurement Considerations . . . . . . 2-1 0 2.6.4 Variations and Comments . . . . . . . . . . 2-24 U n its and Terms . . . . . . . . . . . . . . . . . . . . 2-1 1 2.6.4.1 U pward Ti lt . . . . . . . . . . . . . . . . . 2-25 2.5.2.1 Lu mens . . . . . . . . . . . . . . . . . . . . . 2-1 1 2.6.4.2 Coverage . . . . . . . . . . . . . . . . . . . 2-25 2.5.2.2 Intensity (Ca n d l e power) . . . . . 2-1 1 2.6.4.3 Consistency . . . . . . . . . . . 2.5.2.3 l l l u m i na n ce . . . . . . . . . . . . . . . . . 2-1 1 2.6.4.4 M u ltiple-Lu m i naire 2.5.2.4 L u m i nance . . . . . . . . . . . . . . . . . . 2-1 1 2.5.3 Pri nciples of Laboratory Photometry 2-1 2 2.5.4 Photometric Test Reports . . . . . . . . . . . 2-1 2 2.5.5 Relative and Absolute Photometry . . 2-1 7 . . . . . . 2-25 Arrangeme nts . . . . . . . . . . . . . . 2-25 References for Chapter 2 . . . . . . . . . . . . . . . . . . . . . . . 2-26 Chapter 2 Vision a n d Funda me nta l Concepts T he topics in this chapter comprise the fundamental information the reader needs in order to u nderstand the principles of l ig ht and vision, as well as l ight sources, the measu rement of lig ht, and the various classification systems for outdoor l u mi naires. where one nanometer is equal to 1 0-9 meter. Within this 2.1 Light and the Visible Spectrum The extent to which visibility at n ig ht can be created range, different wavelengths of l ight are perceived as by the use of fixed l ighting is dependent on both the different colors (see Figure 2-1). quantity and quality of the l i g ht that the eye receives, and on the nature of the visual tasks. There is a complex The human eye is not equally sensitive to light of different interrelationship between the many factors involved. By wavelengths. In general, a given amount of energy in either understanding these factors, the lighting designer can the blue (short wavelength) or the red (long wavelength) improve visibil ity for roadway users. area of the spectrum will be perceived as less bright Electromagnetic radiation ranges from cosmic rays that wavelengths. As a result, the color of the light source affects haveextremelyshortwavelengthstoverylong-wavelength the brightness that is seen, and this can influence visibility. than a similar energy level seen in the green or yellow radio waves. Radiant energy that is capable of exciting the retina and producing a visual sensation is considered Figure 2-2 relates the sensitivity of the h u m a n eye to light. The visible portion of the electromagnetic spectrum the wavelength of the light. The solid cu rve has been extends from about 380 to about 780 nanometers (nm),1 internationa l ly sta ndardized and is common ly referred Low Fre q u en c y High Frequency •y Vacuum UV Short Wavelength H a rd � Long Wavelength Radar Soft .. JVV Mic rowave Transmissiions • ''++' Electromagnetic Spectrum - - - M icrowaves Radio Waves - , Wavelength ! i n na nometers or 1 0 "9 meter) 380 400 Violet Blue Figure 2-1. The electromagnetic spectrum. 500 Green 600 Yellow 700 Red 780 Visi b l e Lig ht 2-1 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities to as the V(Ji) curve. V is the symbol representing produces a certai n a mount of energy in the blue region visi bil ity, and la mbda (Ji), is the symbol representing of the spectrum, while another source prod uces a n wavelength. The V(Ji) curve is used a l m ost exclusively identical a mount o f energy i n t h e yellow region. The in i l l u m inating engi neering to express the relationship a mo u nt of l ight prod uced by the yellow source, as between eye response and wavelengths. Section 2.5.4 perceived by h u m a ns, will be considera bly g reater than Spectral Effects and Mesopic Vision d iscusses the that produced by the blue source because the eye w i l l dashed cu rve-referred to as the scotopic sensitivity perceive t h e yellow source as brighter. Determining the cu rve, V'(Ji)-and its relationship to the V(Ji) cu rve. q u a ntity of lig ht, therefore, req u i res appl ication of the eye's photopic sensitivity cu rve to the spectral power 10 9 I ·e :I ...I iii .... I 6 5 Section 2.3.4 will address the val id ity of the V(Ji) cu rve, describing situations where it is inapplicable, and the I associated ramifications in roadway l ighting design . I+ c. Ill 3 I ;; Ill � 2 Qi a: 1 Ill I 2.2 Basic Principles of Vision I The most complex ofthe senses, vision is perhaps the most I important mechanism we have for apprehending the . �����...;:i,__�....,.� . ��---!I o ....� .. i:;...� 380 1780SPD(Jc) V(Jc)dJc 380 I 4 .. ... light power (lumens)= I w :I 0 c are integ rated across the entire visible spectrum: I >... 8 c Ill ·;:; 7 if "' d istribution (SPD) of the light source. Essentially, the two I 420 460 500 540 580 620 660 700 740 780 Wavelength in nanometers (nm) Figure 2-2. Human visual sensitivity as a function of wavelength. world. Vision results from the interaction of eye and brain. From vision come perceptions, and from perceptions we build our individual worlds, always largely affected by the luminous environment. An understanding of this process will guide the design of that environment, and to consider the eye and brain as one system is the best way to understand the biological machinery that enables vision.2 As can be seen from Figure 2-2, at medium and high light levels (photopic range) the V(Ji) cu rve shows very weak The eye contains components that work together to produce sensitivity to violet and blue light. Sensitivity increases an image of the external world on a layer of photoreceptive through the green area of the spectrum, and reaches a cells in the retina at the back of the eye. A combination peak at 555 nm in the yellow-green reg ion. Sensitivity of mechanical, chemical, and neural mechanisms change then declines in the orange band and is low at red the system's sensitivity so that it can operate in light levels wavelengths. At very low light levels (scotopic range, V'(Ji) ranging from faint moonlight to noon sunlight. Complex curve), such as under starlight alone, visual sensitivity neural circuitry is responsible, in part, for motion detection, peaks at 5 1 0 nm, in the green-blue region. Most outdoor color vision, and pattern recognition. Figure 2-3 shows the nighttime l ight levels are in the mesopic range, where anatomical structure of the eye-brain system. both rods and cones are active (see Section 2.2.4 for information on rods and cones); human visual sensitivity then lies between the photopic and scotopic cu rves. The general structure of the human visual system is a series of layers that receive, process, and transmit visual information. These layers are connected by neural pathways Light is not defined and mea s u red p urely as the that convey visual information from one layer to the next. amount of energy i n the 380-nm to 780-nm wavelength The principle layers are the retina, located in the eye, the range. Light is measured i n accordance with the visual lateral geniculate body, located in the brain center, and sensation it prod uces. S u ppose one l i g ht sou rce the primary visual cortex, located at the back of the brain. 2-2 Vision and Fu ndamental Concepts 2.2.3 Function of the Lens. The lens is a m u ltilayered, double-convex structure just behind the iris. It is nearly tra nsparent and, in the you ng, very elastic. I n its relaxed state, the front surface of the lens bulges out, i ncreasing its c u rvature and refracting power. In this state, it can provide up to 25 diopters* of focusing power, and in the flattened state it provides approximately 10 d iopters of focusing power. Figure 2-3. The eye and the principal components of the brain that comprise the human visual system. (I mage © David H. H u bel) of the optical pathway and the beginning of the visual pathway of the visual system. Because of its structure, Though visual information is transmitted by the visual cortex to "higher" parts of the brain, the cortex is usually considered the last stage of the visual system proper. 2.2.1 Structure of the Eye. 2.2.4 Function of the Retina. The retina marks the end The sections below3 describe some of the components of the eye, g iving their structure and their va rious mechanical, optical, and neura l operation functions. Figure 2-4 shows the general structure of the eye. Much of the eye functions p u rely as a n optical machine with the pu rpose of maintaining a focused i mage of the world on the retina at the back of the eye. (For more-deta iled information on the structure and fu nction of the eye, refer to ANSI/ JES LS-7-20, Lighting Science: Vision - Eye and Brain3) function, and complexity, the retina is considered, anatomically, a part of the brain housed in the eye. The retina lines most of the back chamber of the eye and is highly structured in layers that contain three general types of cells: photoreceptors (rods and cones) that absorb optical radiation and produce electrical signals; horizontal, amacrine, and bipolar cells that perform signal processing functions; and ganglion cells that form the optic nerve and conduct these signals to the brain. A few of these ganglion cells are now known to be intrinsically photosensitive themselves, and are part of the body's neuroendocrine system. Figure 2-5 is a peripheral cross-section of the reti na. From front to back, these cells are: ganglion cells, bipolar Figure 2-4. Form and structure of the eye. (I mage © David H. H u bel) 2.2.2 Function of the Iris and Pupil. The iris and pupil are the annulus of tissue and its round center opening, respectively, which control the amount of radiation entering the eye. The i ris provides what we call "the color of the eye." The iris expands and contracts, making the pupil smaller and larger, in response to the brightness and size of objects in the eye's field of view. In general, the brighter the field of view, the smaller the pupil. Figu re 2-5. Cross-section of the retina; the back of the eye is at the right. Optical radiation moves from left to right in this diagram. (Image © David H. H u bel) * I n optics, a diopter is a unit of measure of the refractive power of a lens, having the d i mension of the reciprocal of length a n d a unit equal to the reciprocal of one meter. Abbreviation: D. Sou rce: Dictiona ry.com, http://www.dictiona ry.com/browse/d iopter?s=t. (Accessed 2021 Jul 29) 2-3 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities cells, amacrine cel ls, horizontal cel ls, photoreceptors The blind spot is that place in the retina where a l l (rods and cones). axons from ganglion cells collect a n d exit t h e eye, a n d so it contains no photoreceptors. Between this 2.2.4.1 Photoreceptors. Considered a natomically, m i n i m u m density and the maxi m u m density at the there are two types of photoreceptors involved i n fovea, photoreceptors are distributed throughout the spatial vision, named accord ing t o shape: rods a n d retina in a non-uniform way, as shown in Figure 2-7. The cones. Photoreceptor cells convert optical rad iation density of rods and cones shown i n the fig u re is along to neura l signals. The photopigment contai ned i n a a h orizontal section of the retina, from ear-side to nose­ photoreceptor cell a bsorbs optical side, passing through the b l i nd spot and the fovea . rad iation a n d cha nges shape, which triggers a process that releases a neura l transm itter. The more rad iation is a bsorbed, the more transmitter is released. 'E There are four types of photopigments: one type fou nd in a l l rod photoreceptors and three types found i n cones. The likelihood that these photopigments will absorb incoming radiation is a function of the wavelength. The spectrally 1 60,000 E 1 20,000 lii Cl. "' 0 .. 80,000 ... QI a: 40,000 Cl. QI ,. Cones +- + selective absorption of the photopigments defines the 0 overall spectral response of the photoreceptors. The 40 action spectra of the three types of cones are shown in Visual Angle (degrees) Figure 2-6. The three photopigments found in cones 20 have peak sensitivities at about 575, 525, and 450 nm and are cal led the long, midd le, and short wavelength (L, M, S) cones, respectively. 0.0 >- Front of Eye -0.5 Figure 2-7. Distribution of rods and cones in the human ·; - 1 .0 .;:: · retina. 'iii -1 .5 c J: -2.0 � -2.5 .;:: · Ill For the reasons noted, peripheral vision is less acute '& -3.0 than foveal vision u nder most circumstances. H owever, ...J periphera l vision is h i g h ly i m porta nt to roadway � -3.5 -4.0 400 users. When a hazard a ppears, it will very often first 500 600 700 Wavelength in nanometers (nm) Figure 2-6. Cone sensitivities as a function of wavelength. appear off the roadway. Exa mples would i nclude a deer ru nning toward the roadway, or another vehicle a pproaching from a side road. It is u n likely that the axis of the eye is directly pointed toward such objects at the moment they appear. Peripheral vision is bel ieved to be i mportant in the initial detection of such objects. 2.2.4.2 Photoreceptor Distribution. The fovea is an Visib i lity through peripheral vision has been shown to area of the retina where the density of photo receptors is be related to coll ision rates. g reatest and, conseq uently, where the image is assessed most acutely. In this region of the retina, photo receptors Because peripheral vision at n ig ht relies heavily on are thinnest, thus permitting very tight packi ng. O n ly the rods, providing l ighting to stim ulate the rods is cone photoreceptors are present in the fovea. beneficia l . Furthermore, because the light level affects 2-4 Vision and Fu ndamental Concepts the relative extent to which the rods and cones are The inability of the lens to focus objects over a full range active, the interrelationship between l i g ht level, retinal of distances-for example, from the vehicle dashboard activity, and visibil ity is obviously complex. (See also to distant objects on the roadway-is a common eye Section 2.3.4.1 Limitations of the V(A) Curve.) defect. Myopia, or near-sightedness, is the inability to The relationship between these basic visual functions and the design of a lig hting system to provide visibility in nighttime d riving will be addressed in su bseq uent cha pters of this Recommended Practice. 2.2.5 Adaptation. Adaptation is the process by which a l l or part of the retina becomes accustomed to more or less light than it was exposed to d u ring a n i m mediately preced ing period. It results in a change in the sensitivity to l i g ht. (Note: Adaptation is also used to refer to the final focus objects at a long distance, while hypermetropia, or far-sightedness, is the inability to focus objects at a close distance. Both conditions can be corrected by eyeglasses. Older persons in particular usually suffer from some degree of presbyopia, which is caused by reduced plasticity of the lens. Presbyopia can create focusing difficulty for near and distant objects. This can be partially overcome with the use of bifocal or graded-focal eyeglasses. Good lighting assists in combating all of these defects. The focusing ability of any lens, including that of the eye, is superior for rays passing through the center of the lens. state of the process; e.g., reaching a state of adaptation Rays traveling through the outer area of the lens tend to to a specific level of l u m i nance.)1 focus less accurately on the retina because of a common When the retina is adapted to a l u minance less than are high, the pupil diameter decreases, thus excluding the about 0.034 cd/m2, this is referred to as dark adaptation. rays that would have passed through the extremities of the This is a lso the range of scotopic vision (see Section lens. This improves focusing, provides a clearer scene, and 2.1). When the eye is adapted to a l u minance that is improves visibility by increasing the "depth of field." lens defect termed spherical aberration. When light levels g reater than a bout 3.4 cd/m2, this is referred to as light adaptation. This is a lso the range of photopic vision. 2.3 Visibil ity Fundamentals and Principles 2.2.6 Accommodation. The lens of the eye can change its cu rvature and thickness when acted upon by the ciliary m u scles. This process, known as accommodation, enables the retinal image to be brought i nto focus for objects at different d istances from the eye, as i l l u strated in Figure 2-8. Visib i lity and the factors i nfl uencing visual perception at night a re complex issues. As has been described, the eyes u ndergo adaptation to different l u minance levels, enabling vision u nder very low l ig ht levels. I n practical terms, however, the nighttime driving scene does not consist solely of the road su rface and potential hazards to be detected, but includes extraneous l ig ht from bright sources. These may be opposing vehicle Lens Distant Vision hea d l i g hts, off-roadway sou rces, and street l i g hting l u m i na i res. Because of this wide range of l u minances, the eye can not be idea lly ada pted to all l u m i na nces i n � Le " ar v isi o n ---== ������ N e =::::= ---____ � t h e field o f view. An i mportant consideration, therefore, is to counteract the effect of the bright sources in the fiel d of view by i ncreasing pavement l u m inance. This principle can be illustrated by the reduction in visibil ity caused by opposing headlights. The red uction can be major at night, yet be very little d uring daytime. This is because the h igher general level of daytime l u m inance causes the adaptation level of the eyes to increase, and Figure 2-8. Examples of eye accommodation for distance therefore vision is less susceptible to the effect of the vision and near vision. hea d l i g hts. 2-5 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Even under ideal situations where no extraneous sources are present and the eye is adapted to the l u m i nance of the pavement, the actual l u minance level is i mportant. Contrast sensitivity expresses the a bility of the eye to discern objects and backg rounds of d iffering l u m ina nce. When light l evels are increased, contrast sensitivity also i ncreases. As contrast sensitivity increases, the eye is more readily able to discern objects, or visual tasks, that may provide only a low contrast aga inst their background. The effect of bright l ig ht sou rces is not l i m ited to shifting of the eye's adaptation level; such sou rces a lso create g l a re, described below, which further l im its the eye's capability to d iscern objects that are difficult to see. I ncreasing pavement l u m i na nce by the provision of well-designed roadway lighting assists the eye in "seeing through" the glare. 2.3.1 Contrast. Objects may be discerned through adequate contrast. For example, a n object lying on the roadway w i l l usually have a l u m i nance that is d ifferent from that of the su rrou nding pavement. If the object has higher l u m inance than the background, it is said to have positive contrast. If the object l u mina nce is lower than that of the background, it is seen in silhouette and has negative contrast. This principle is illustrated i n Figure 2-9. Examples of negative contrast (top) and positive contrast (bottom). Figure 2-9. • Contrast is calcu lated from: C = (L, - Lb)!Lb • L , = Lumina nce of the task Lb = Luminance of the backg round A high contrast between the task and background such that the contrast exceeds the threshold contrast by as g reat a factor as is feasible where: C = Contrast Sufficient light to create a high level of contrast sensitivity and therefore a low threshold contrast • Lim ited extra neous factors, such as glare, that in effect increase the threshold contrast Over a range of locations, the l u m inance of an object is When contrast is very low, task visibi l ity may be below l i kely to be higher than that of the background (positive threshold, and the task is not likely to be seen. At contrast). This usually occurs for objects just beyond the high contrasts the converse is true. U nder glare-free, l u m inaire, where the vertical or near-vertical surface of u n iform backgro u nd cond itions, the contrast that the object is strongly i l l u m i nated. Between the roadway provides a 50:50 chance of object detection is referred areas of positive and negative contrast l ies an a rea where to as threshold contrast. Threshold contrast is affected contrast reversal occurs. This area is where the contrast by many variables. It is reduced by i ncreasing pavement is changing from positive to negative or vice-versa, and l u m i nance, other factors being equal, because of the where task contrast may lie below the threshold. This is increase in contrast sensitivity of the eyes. Therefore, illustrated by Figure 2-1 0, which shows a n a rray of s m a l l the pu rpose of roadway l i g hting to is provide: vertical targets. Targets near t o t h e d river's position are 2-6 Vision and Fu ndamental Concepts seen in negative contrast, those at the farther distances source of high intensity is present in the field of view, this are in positive contrast, and between these extremes scattering tends to superimpose a luminous haze over the is a n area where target d iscern ment is d ifficult or retina. The effect is similar to looking at the scene through i mpossi ble. Such areas of contrast reversa l occur twice a lu minous veil. The luminance of this "veil" is added to per l u m i na i re cycle, and may be a source of accidents both the task and background luminance, thus having the due to inadeq uate visibility of the visual task. effect of reducing contrast. The effect is termed disability glare or veiling luminance, and it may be numerically evaluated by expressing the luminance of the equivalent l u m inous "veil." A well-known example of this is trying to see beyond oncoming headlights at night. Because of the contrast red u ction from disabi l ity g l a re, visibility is decreased. Increasing l u m ina nce w i l l cou nteract this effect b y i ncreasing t h e eye's contrast sensitivity. A well-designed roadway lighting system will minimize g lare by employing luminaires that have proper optical design (e.g., those with a low-G BUG rating). Disability g lare Figure 2-10. Small target contrast. can be calculated, and maximum recommended levels (as (Photo courtesy of Lighti ng Sciences.) veiling luminance) are defined in Sections 1 0.5 and 1 1 .7. 2.3.2 Visual Acuity. 2.3.3.2 Discomfort Glare. Discomfort g l a re is a further Visual acuity is a measure of the ability to distinguish deta i l under a given set of result of overly brig ht l ig ht sources in the field of view conditions. It is infl uenced by contrast, both l u m inance a n d causes a sense of pain or a n noyance. While its a n d spectra l. Larg e objects have a lower contrast exact cause is not known, it may resu lt from pain in the threshold than small objects of equal l u m i na nce, other m uscles that cause contraction of the pupil. factors being equiva lent; as a resu lt, larg e objects are easier to see. Light sou rces that provide better Discomfort g l a re, which can cause effects ran g i n g color rendition improve color contrast and make small from a n i ncreased blink rate t o tears and pain, does objects easier to disti nguish from their background. not red uce visibility. It is a lso genera l ly accepted that redu cing disability glare will red uce d iscomfort glare. 2.3.3 Glare. N o n - u n iform ities in the visual field, It i s im portant to note, however, that it is possible to particularly those caused by bright sources, affect the reduce discomfort g lare and i ncrease disabil ity glare. adaptation level of the eye. Because these sou rces tend North American roadway l ig hting standards do not to fluctuate as the d river proceeds, the adaptation level specify numerical l i m its for d iscomfort glare. Form ulas is constantly changing; this is cal led transient adaptation. have been developed to q u a ntify d iscomfort g l a re Roadway l i g hting aids the eyes in adapting to higher based on subjective ratings of g lare under a variety l u m i na nce than can be provided by headlig hts a lone. of conditions.4 No instrument has been developed for Bright sources create other effects, col lectively termed the natu re of calcu lation form ulas their measurement the measurement of discomfort g la re, and because of g lare. These should be avoided as much as is practical. wou l d req uire the use of a luminance mapping camera cou pled with a processor with appropriate software. 2.3.3.1 Disability Glare. Light rays passing through the eye are slightly scattered, primarily because of diffusion 2.3.4 Spectral Effects and Mesopic Vision. Lighting in the lens and in the vitreous h u mor, which fills the large levels i n this standard are based on photopic light levels interior chamber of the eye (see Section 2.2). When a light (please reference Chapter 10 for further expla nation). 2-7 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities power distribution (SPD) of the light source, using the V(A) curve for eye sensitivity, is described in Section 2.1 Light and the Visible Spectrum. The l umen value so computed then becomes the basis for all of the other quantities in a lighting design, such as intensity (candelas, cd), illuminance (lux [Ix] or footcandles [fc]), and luminance (candelas per square meter, cd/m2). If the V(A) curve is inaccurate or inapplicable, it fol lows that the lumen values and other quantities will not accurately represent real conditions. 9 » v c GI ·;:; � w "' :I 0 c Visibil ity, especially u nder mesopic conditions, is not a simple matter. I l l u m i nating eng i neers and vision scientists 8 I 7 I 6 I I ·e 5 I � .. 4 I Cl. VI 3 :I .... v GI GI > 2.3.4.1 Limitations of the V(A) Cu rve. I/ 10 The method of computing lumens from the spectral ; "' Qi a: 2 1 I I I I . �����--�....;:..._���� o .._.__:;...� 380 420 460 500 540 580 620 660 700 740 780 have known for over a h u n d red years that the way in Wavelength in nanometers (nm) which the visual system responds to different l ight sou rce spectral d istributions depends on the lighting Figu re 2-1 1 . Human visual sensitivity as a function of and viewing conditions.5•6•7 Equ iva lent l u men output of wavelength. different light sou rces may be perceived as different. However, light sou rces, such as lamps, are given a rated As mentioned in Section 2.1, high l ig ht level cond itions, lumen output as if the h u m a n sensitivity to the light where l u m i nances are generally in excess of about 5 cd/ output of any particu lar l ig ht source was always the m2, are termed photopic levels. The V(}.) cu rve appl ies to same. such conditions. When the light level is very l ow (below The photopic spectral sensitivity cu rve, V(A) (see Figure This is typical of starlight levels at nig ht. Between these 2-1 1), is the sensitivity cu rve of the visual system that is two, conditions are referred to as mesopic and apply to used m ost often to relate human visual response to the twil ight and the light levels frequently found in street wavelength of the light sou rce. l ig hting at night. Figure 2-1 2 i l l u strates the ranges. 0.001 cd/m2), the conditions are described as scotopic.1 (Rods & Cones) (Sta r l i g ht, R o di Visi on) I I Lumina nce· 0.000 1 0.00 1 Ph oto p i c Visio n Meso pic Vision Scoto pic Vis i o n (Cone Vision) I I I I I II O.Ol 0. 1 1 .0 Figure 2-12. Scotopic, mesopic, and photopic light levels. (Graphic cou rtesy of Don Mclean) 2-8 I I 1 0.0 -cd/m2 5.0 Vision and Fu ndamental Concepts U nder scotopic conditions, the eye's visual response is the same proportion without changing the respective q u ite different from that u nder photopic conditions, as spectral distributions. shown by the dashed cu rve in Figure 2-1 1 . This effect has been known for over a centu ry, and is cal led the The eye response does not shift suddenly from photopic Purkinje shift. The eye's sensitivity to yellow and red light to scotopic conditions. It u ndergoes a grad u a l change as is greatly reduced, while the response to violet, blue light levels a re reduced through the mesopic range. and blue-green l ight is greatly increased. If lamp l u men The eye's mesopic response is a combi nation of the output has been determ ined using the photopic V(J.) photopic and scotopic responses. cu rve, but viewing cond itions are below the photopic range, the l u men output value w i l l not give a n accu rate The differences in the reti nal sensors and their spectral ind ication of the effective amount of l ig ht produced. responses affect visibil ity u nder different l ig ht sou rces. Figure 2-13 i l l u strates a n exa mple. The SPD of a typical high pressure sodi u m (H PS) source is shown agai nst the photopic and scotopic sensitivity functions. This source is h i g h ly efficient at generating lig ht, one of the reasons being that its high o utput in the yellow region is close to the peak sensitivity wavelength of the V(J.) c u rve-but not the peak sensitivity wavelength of the V'(J.) cu rve. As eye fu nction passes from photopic to scotopic vision, the cu rve of spectra l l u m inous efficiency changes, with the wavelength of maxi m u m efficiency being d isplaced toward the shorter wavelengths. There is a relative increase in the apparent brightness of short­ wavelen gth l i g hts, compa red with those of l onger wavelengths, when thei r l u mi nances are reduced in Therefore, V(J.) does not necessa rily represent the spectral sensitivity for many visual responses u nder nighttime d riving conditions, except for objects withi n t h e rod-free fovea.8 Because o f this, t h e source l u men va lue may not be predictive of the visua lly effective light q u antity, nor of the appearance of a l i ghted su rface or object as seen by the eye at night. If l ig hting quantities have been determined using the photopic V(J.) cu rve but viewing conditions a re i n the mesopic or scotopic range, the lighting quantities will not be predictive of the visua l effect. 2.3.4.2 Impacts on Roadway Lighting Design. The spectral content of street and hig hway lighting products is varied and, to a limited extent, control lable. Luminaires are available with many different blends of spectra, from nearly monochromatic yellows and reds to combinations 10 of red, blue and green that appear as white light to I 9 :s 0 c 5 � ... 4 :s I I ..... ... GI c. VI GI > ;: "' Qi a: 1 on design are discussed in Chapter 1 0. Spectral Power Distribution of HPS Lamp I+ I + 3 2 of their projects. The potential effects of spectral content +/ 6 ·e l u m i naires to achieve effects of color in the environment I » 8 c GI ·;:; 7 � ... w "' observers. Designers may select the spectral content of I It is important to note that al/ light level recommendations in this standard are based on the photopic V(J.) curve. Mesopic factors are not applicable to the recommendations in this standard. 2.3.5 Effects of Age on Vision. I .1111 llllil.._.li.li..�=-_;_�_..:::::..._ :11 ���-' 0 1...'-i 380 420 460 500 540 580 620 660 700 740 780 I ncreasing age decreases contrast sensitivity and reduces the eye's sensitivity to blue light. These effects a re implicitly accou nted for in roadway sta ndards and have been Wavelength in nanometers (nm) exp l i citly exam i ned for parking lot l ig hting. Figure 2-13. High pressure sodium (HPS) SPD curve superimposed on photopic and scotopic spectral I n 201 4, the median age of the U.S. popu lation was 37.8 luminous efficiency curves. years, with 27.1 % of the popu lation under 21 and 1 4.5% 2-9 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities of the popu lation over 65.9 (Refer to Chapter 17 and 2.4 Light Sou rces Light sou rces have a direct effect on visibi l ity. This is because every l ig ht source has significant characteristics related to the q u a l ity or quantity of light eventually generated by a l u m inaire. Very im portant characteristics include the a bil ity of the light source to render color or to i m prove peripheral vision, for exa m ple. Light sources that i m prove color rendering and visibility in the nig httime environment a re genera l ly more desira ble. Other key factors such as the size of the l i g ht sou rce, I/ 10 Annex G for additional information.) 9 » v c GI ·;:; � w "' :I 0 c 8 6 ·e s � .. 4 :I ..... v GI Cl. VI GI > ; "' Qi a: I 7 3 2 \ 1 0 380 420 460 is widely used in the ma rketplace. Light sou rces are discussed in more deta il in Section 6.3 Light Sources and Lamps. 540 ' 620 580 660 700 740 780 Wavelength in nanometers (nm) its morta l ity rate, its abil ity to q u ickly restrike, and its susceptibility to temperature a l l play a role in whether it 500 Figure 2-1 4. Unfiltered photodetector sensitivity vs. eye (rod and cone) sensitivity. such spectral output lies at wavelengths where the filter correction is inadeq uate. Construction of an accu rate filter is complex and time-consuming, but errors caused 2.5 Measurements by inadequate filtering when measuring such sources can be significant with low-cost instruments. 2.5.1 Measurement Considerations. Light measure­ ment for roadway systems currently falls i nto two gen­ The reader is referred to IES documents in the LM series eral categories: for more i nformation on photometric testing proced u res. • Laboratory photometric testing to esta blish the basis for performa nce and design • Field photometric measurements to esta blish performa nce achieved The accuracy of spectral response of a filtered photodetector is ind icated by its fi' rating (pronounced f-one-prime), developed by the I nternational Com mission on I ll u m ination (CIE). For field measurement of discharge Similar types of photodetectors, or photocel ls, are used for both types of measurement. To measure l ight properly, a photodetector must have a spectral response sou rces, fi ' is recommended to be 2.0 percent or less. When purchasing a meter, the user should request the fi' rati ng from the manufactu rer. curve that mimics the human photopic visual sensitivity curve, V(Ji). Silicon has higher sensitivity in the blue and For field instruments, measu rements can i nvolve red regions than the human eye, as shown in Figure intercepting rays traveling at a wide range of angles from 2-14. A colored filter must therefore be placed over the the various l u minaires to the photodetector. To g ive a n photodetector to tune the photodetector's effective accu rate reading o f t h e light level, t h e photodetector response to the V(Ji) cu rve. Ideal ly, the combined spectral must respond to the intensity of the rays in accordance response of the photodetector and filter should closely with the cosine of the angle of incidence. (Refer to match the V(Ji) curve at a l l wavelengths. This is particularly Sections 3.4.1 and 3.8 for discussion of the cosine important for measurement of sou rces with pronounced, law.) Field i l l u m i nance meters therefore need a cosine "spikey" spectral output lines, such as H I D, fluorescent, diffuser (cosine receptor) in order to measu re accu rately. and RGB LED sources, as significant errors can occur if This is normally a white plastic cover situated over the 2-10 Vision and Fu ndamental Concepts photodetector and shaped to optical ly change the path The user may be i nterested only in the l u minous flux of the rays striking the photodetector to overcome a ny rad iating from the sou rce over a specified a n g u l a r non-cosine effects. Field i ll u m i na nce meters should not ra nge. T h e u n i t used i s t h e same, as t h e terms luminous be used without a cosine receptor. (Refer to Annex A for flux, lumens, and lumen output refer to the flow of light from a l ig ht source or l u minaire, whether the total additional information on field measurements.) a m o u nt or over a specified range of d i rections. For laboratory testing, movement of the photodetector with respect to the l u mi n a i re i nvolves the use of special ized equ ipment termed a goniophotometer, which is described in Section 2.5.3 - Principles of Laboratory Photometry. 2.5.2.2 I ntensity (Candlepower). Intensity (sometimes called candlepower) and lumens are separate terms. Luminous intensity refers to the concentration of l ig ht in a particular direction, while lumens represent a total q u antity of l ight emitted over an angular range. I ntensity 2.5.2 Units and Terms. Certai n basic u nits and terms m ust be understood in order to read and use photometric test reports. Knowledge of fou r fu ndamental qua ntities is needed. These include: is expressed in candelas (cd). The intensity of a l ig ht sou rce will usually be d ifferent over the va rious angles of emission. A photometric test report provides intensity va l ues at specific measu rement • Lumens a n gles, and if the i ntensity has been measured i n many • I ntensity (or candlepower) directions, the light distribution can be known with • l l l u m i na nce • Lum ina nce reasonable accu racy. 2.5.2.3 llluminance. I/luminance is a measu re of the density of light i ncident on a surface. The n u mber Figure 2-1 5 represents the passage of light from the of l u mens incident on a surface (real or imaginary) is sou rce to a surface and then to the eye. The fu ndamental divided by the a rea of the surface to obtai n the average four qua ntities a l l can be visual ized by using this fig u re. i l l u m inance over that a rea. The unit of i ll u m i na nce is the / lux (Ix), where one lux is eq ual to one l u men per square Refiector / meter. In the U nited States Customary System (USCS), Surface % 1-=o-��,__ �--,------�--------'---r q, ---7'. �,� ....._ nt ns ----� '---�� ---"' � c� y_ le_ it_ ��� (o_ r_ _ ___ a_n_ d_ po_w_ e r r)� ::::-r �:: __,..-9 ('$ ,_ l_e - - the unit is the footcandle (fc), where one footcandle is equal to one l u men per square foot. It is i mportantto note that the eyes do not see i l l u minance, the light i ncident on a su rface. They see o n ly the portion of the l ight that is reflected toward them. An exa mple is a white line on a black asphalt su rface. The appearance Candelas (cd) Lu mens per m' (lux) Lu mens per ft' (fc) of the white line is very different from that of the black su rface, even though each may be receiving identical i l l u m inance. For situations where task locations and reflectance properties a re varied, such as pedestrian wal kways, i l l u m i nance is used as it provides a measu re Figure 2-15. Relationship of basic lighting terms. of the potential for visibility. For street lighting, where the street provides a known reflectance against which targets are viewed, l u minance is cu rrently the preferred 2.5.2.1 Lumens. The light generated by a l ig ht source is metric (see Section 2.5.2.4). referred to as luminous flux and is measured in l u mens. The l u men output of a l i g ht source or l u m inaire is the 2.5.2.4 Lumina nce. To u nderstand what the eye sees, total a mount of l ight emitted in all directions. one m ust consider luminance, the concentration of light 2-1 1 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities (intensity) reflected toward the observer per unit a rea Swing Arm Axis 1 i of su rface. Where intensity applies to a point source, Luminaire Rotation Luminaire � Raise/Lower or a source that is small enough or far enough away Mi rror Rotation to act as a point sou rce, luminance is a measu re of the concentration of l ig ht em itted or reflected from a n a rea source. It is essentially the i ntensity divided by the a rea of the source and is measu red in candelas per square meter (cd/m2). 2.5.3 Princi ples of Laboratory Photometry. Photometric testi ng of a l u m i naire i nvolves gathering data that characterize its intensity (ca ndlepower) d is­ tribution, in candelas. Once the intensity va l ues for a l l directions of emission are known, a photometric test Figure 2-1 6. Example of a mirror goniophotometer. report can be generated. (Photo cou rtesy of Lighting Sciences I nc.) The is of measurement a device g o n i o p h otometer. goniophotometers used Several a re in a l a boratory d i fferent ava i l a b l e to types rotate a photodetector around the l u m i na i re, thro u g h both the l ight path to be nearly horizontal, can achieve a long test d istance withi n a relatively compact space, without req u i ring excessive cei ling heig ht. horizontal and vertical a ng les. Light readings are taken at n u merous points throug hout the a n g u l a r g rid in Modern goniophotometers operate u nder computer fine angu lar steps so that the ful l light distribution is software control. Mirror and l u m i na i re rotation a re accurately quantified. automated. The photodetector a m p l ifier feeds a n a n a l og-to-digital converter that relays t h e l ight readings The most common form of laboratory apparatus is the to the computer, which builds a data a rray of l ig ht m irror goniophotometer, shown in Figure 2-16. A large intensity versus angle. Thousa nds of i ntensity readings mirror rotates i n a vertical circle around the l u m inaire can be collected i n a relatively short time. and reflects l i g ht to a fixed photodetector. A shield in front of the photodetector prevents light from reaching Data processing software reads the col lected intensity the detector directly. As the mi rror rotates throug h a array and produces test reports that provide the various 360-deg ree sweep, the photodetector "sees" the light required tables and g raphs. Also produced is a n electronic emitted by the l u m inaire in a vertical plane just as if the data file that stores the intensity (candela) array and other detector itself had been rotating vertically a round the required information in a standard file format. This file l u m i naire. can be used as input to numerous application programs Once a vertical scan by the mi rror has been completed, ana lysis. In North America, the most common file format the l u m i naire rotates a few degrees horizonta lly (around is that established by the ANSI/I ES in LM-63-19.1 0 that are available for computerized lighting design and a vertical axis that passes thro u g h the l u mina ire), and another vertical scan by the mi rror is performed. This is 2.5.4 Photometric Test Reports. Test reports provide repeated u ntil i ntensity readings have been collected in the measu red i ntensity d istri bution of the l u m i naire and vertical planes at all desired horizontal angles around certai n additional data calculated from the i ntensity the l uminaire. va l ues. Typica l ly included a re: • There a re I ES and C I E req u i rements regarding the • Intensity (candela) tables A polar g raph of i ntensity cu rves showing the m i n i m u m d ista nce between the l u m i na i re and the vertical plane and horizontal cone sl ice that photodetector. The m irror g oniophotometer, by turning conta in the maxi m u m intensity 2-12 Vision and Fu ndamental Concepts BUG rating (older reports may report the old cutoff table may provide a bbreviated data on ly, with the ful l classification) data a rray being given i n the accom panying standard • lso-il l u m inance d iagrams electronic data file. The vertical and horizontal angles of • Coefficients of Utilization table or g raph • Correlated color tem perature (CCT) • Operating cu rrent • Luminaire l u mens • the maximum intensity will be ind icated. Figure 2-1 8 provides a n exam ple intensity summary table. The maxi m u m i ntensity in this example occurs at 57.5 deg rees V, 55 degrees H. The i ncrease in intensity a round the maxi m u m ca n be seen, correspond i n g For desig nation of i ntensity values, a standard a n g u l a r t o bea ms that would b e d irected up and down the coordinate system h a s been developed (see Figure roadway to fil l i n dark areas between l u m inaires. 2-17). In Type C photometry, which is the type used for most l u m inaires (floodlig hts are tested with Type L i g ht intensity distributions a re freq uently g raphed B photometry), vertical ang les a re designated as 0 as polar plots. Figure 2-19 provides an exa mp le. The deg rees for straight down, or nadir; 90 degrees at l u m i naire is i magined to lie at the center point of the horizontal; and 1 80 degrees for stra ight up, or zenith. g ra p h . At a ny particu lar angle, designated as a rad i a l l i ne from t h e graph center, t h e distance from t h e center A horizontal angle ofO degrees (see Figure 2-17) is typically to the cu rve ind icates the applicable i ntensity. The toward the front of the l uminaire. In roadway luminaires, intensity scale is provided by the concentric circles. this indicates the direction corresponding to across the roadway, perpendicular to the curb, for the luminaire's Figure 2-1 9 a lso i l l ustrates the vertica l plane and normal mounting orientation. Horizontal angles increase horizontal cone slice where the maxi m u m i ntensity for counterclockwise rotation, with the luminaire viewed occurs. The l eft-side table and left half of the g raph from above. Data are usually averaged for the left and right provide the i ntensity distribution from 0 to 1 80 degrees sides of the luminaire (about the vertical plane defined by vertical for the vertical p lane that runs through the angle the 0- and 1 80-degree horizontal angles). of maxim u m intensity. The right-side table and right half of the g raph i l l u strate the intensity distribution at a A photometric report's intensity tabu lation lists the fixed vertical angle that corresponds to the maxim u m intensity va lues for the measured ra nge of data. The intensity. This, in effect, forms part o f a cone a round the l u m i naire, with the half-apex angle of the cone being the vertical angle of the maxi m u m intensity. Several classification systems for roadway l u m i naires are com puted from the intensity data and are covered in deta i l in Section 2.6. 00 Horizontal----­ (x) 1 80° ,, _______, Horizontal (-x) An iso-i l l u m inance plot, i llustrated in Figure 2-20, may also be com puted from i ntensity data and w i l l i l l u strate the pattern of l ig ht falling onto the pavement. Using the inverse-square and cosine laws, d iscussed in Sections 3.4.1 and 3.8, the i l l uminance can be determined at any point on the contour l i nes, which are assumed to lie 00 Vertical (-y) on the horizontal roadway su rface. The iso-i l l u m i nance diagra m i n Figure 2-20 shows contours of equal levels Figure 2-17. Coordinate system for Type C luminaire of l ux. Alternatively, the iso-i l l u m i na nce diagra m may photometric tests. have u n its of footcandles instead of l ux. 2-13 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway and Parking Facilities VERT . ANGLE x .0 5.0 10 . 0 15 . 0 20 . 0 25 . 0 30 . 0 35 . 0 40.0 45 . 0 50 . 0 55 . 0 57 . 5 60 . 0 65 . 0 70 . 0 75 . 0 80 . 0 85 . 0 90 . 0 .0 5.0 10 . 0 15 . 0 20 . 0 25 . 0 30 . 0 35 . 0 40 . 0 45 . 0 50 . 0 55 . 0 57 . 5 60 . 0 65 . 0 70 . 0 75 . 0 80 . 0 85 . 0 90 . 0 I NT ENS I TY ( CANDLEPOWER ) HORI ZONTAL ANGLES y 25 . 0 35 . 0 15 . 0 45.0 - STREET S I DE 55 . 0 75 . 0 65 . 0 85. 0 1 672 1 58 4 1589 1557 1 5 67 1 67 9 1826 2385 3360 4 599 6662 8 63 3 8884 8230 5632 4 61 9 2 930 554 32 0 1 67 2 1640 1 668 1 557 1511 1 4 57 1 3 92 1 32 8 1 308 1287 1421 164 6 1691 1687 1 67 5 1 5 02 1157 100 12 0 .0 5.0 1 67 2 1518 1 5 62 1 6 02 2 1 68 3648 34 4 2 2 3 92 2 5 98 2 632 1948 1 3 68 1 1 66 982 512 244 170 82 4 0 1 67 2 1506 1538 1599 2222 3721 348 9 2471 2 62 7 2568 1885 1302 1116 94 0 454 241 173 83 2 0 90 . 0 HORI ZONTAL ANGLES y - STREET S I DE 9 5 . 0 1 0 5 . 0 1 1 5 . 0 1 2 5 . 0 1 3 5 . 0 1 4 5 . 0 1 5 5 . 0 1 65 . 0 1 7 5 . 0 1 8 0 . 0 1 672 1648 1677 1 5 67 1511 448 1374 311 304 1253 1279 1345 1 357 1 352 1338 1304 1072 68 12 0 1 67 2 1 65 5 1684 1570 1511 1443 1354 1299 1279 1230 1231 1257 1265 1 2 62 1257 1247 1035 SB 9 0 1 67 2 1 50 8 1 52 6 1616 2156 3647 4 1 92 3250 2864 234 6 1718 1443 1 3 62 1 10 1 520 38 3 342 285 5 0 1672 1 669 1695 1 57 9 1504 1416 132 1 1284 1259 1219 1196 1199 1204 1208 1206 1199 962 49 10 0 1672 1516 1 535 1 633 1 995 3191 4 32 9 4 37 2 3288 2 1 67 1 62 8 1631 1 3 64 1 003 654 608 617 522 2 0 1 67 2 1 67 4 1 6 94 1599 1 4 94 1 398 1 33 3 1 30 1 1277 1241 1189 1174 1 1 60 1 152 1145 1121 92 3 66 14 4 Figure 2-18. Example of a luminaire intensity table. 2-14 S UMMARY 1 67 2 1533 1550 1641 1780 2405 3774 4 8 37 4 94 9 3427 2348 1599 1389 1 1 92 915 806 752 593 5 0 1 67 2 1680 1 6 92 1 63 3 1504 1418 1374 1342 1301 1233 1 172 1096 1062 1045 1047 1 03 8 918 103 14 4 1672 1553 1 5 68 1616 1 639 1 90 0 2 657 4421 57 64 5556 5545 4548 3940 3318 1 9 95 1277 967 449 9 0 1672 1 68 9 1 6 95 1 6 65 1526 1450 1423 1 3 97 1314 1 1 93 1 0 98 1038 1001 969 959 954 886 205 14 7 1 672 1 699 1 699 1 665 1543 1 4 63 1428 1 3 99 1289 1128 1 027 979 954 925 872 842 769 151 12 2 1 67 2 1 60 9 1 61 6 1536 1501 1536 1518 1 5 94 1853 2 5 93 4 1 18 5 98 2 6519 6616 6560 6596 527 1 791 52 2 1 67 2 1707 1707 1 655 1536 1455 1411 1 337 1 1 97 1054 94 5 891 8 67 842 791 742 64 7 97 15 2 1 672 1626 1643 1531 1489 1 4 72 1443 1423 1426 1 65 0 2515 334 0 3535 377 9 4 02 8 2 64 6 1 5 67 227 25 0 1 672 1711 1711 1643 1 4 97 1445 1414 1291 1 1 33 1005 904 839 808 777 713 701 691 254 24 2 1 67 2 1709 1713 1 64 5 1 4 94 1445 1 4 08 · 1276 1116 98 9 884 815 788 754 688 698 715 273 22 9 1 67 2 1714 1724 1640 1494 1 4 50 1 4 02 1 2 60 1 098 972 874 810 782 742 688 698 694 210 20 10 Vision and Fu ndamental Concepts I NTENS ITY ( CANDLEPOWER) INTENSITY ( CANDLE POWER ) I N MAX . IN MAX . PLANE CONE ANGLE INTENSITY ANGLE I NTENSITY .0 5.0 10.0 15.0 20 . 0 25 . 0 30 . 0 35 . 0 40.0 45.0 50 . 0 52 . 5 55.0 57 . 5 60 . 0 62 . S 65.0 67 . 5 70 . 0 72.5 75.0 77 . 5 80 . 0 82 . 5 85 . 0 B7 . 5 90 . 0 95 . 0 1 05 . 0 115.0 1 25 . 0 135 . 0 145. 0 1 55 . 0 1 65 . 0 1 75 . 0 l BO . O 1 67 2 1584 1 58 9 1 55 7 1567 1679 1826 2385 3 3 60 4 5 99 6 662 7800 8633 8884 8230 6965 5 632 4 951 4619 3918 2930 1748 554 115 32 5 0 0 0 0 0 0 0 0 0 0 0 .0 5.0 15.0 25.0 35 . 0 45.0 55 . 0 60 . 0 62 . 5 65 . 0 67 . 5 70.0 72 . 5 75.0 77 . 5 80 . 0 82 . 5 85.0 87 . 5 90 . 0 95 . 0 1 05 . 0 115.0 125 . 0 135 . 0 145. 0 1 55 . 0 1 65 . 0 175 . 0 l BO . O 1 1 66 1116 1362 1 3 64 1 38 9 3940 8884 8454 7 5 61 6519 5547 4746 4 101 3535 3006 2495 2036 1691 1474 1 357 1265 1204 1 1 60 1 0 62 1001 954 867 BOB 788 782 MAXIMUM INTENS I TY ( CANDLEPOWER ) : 8884 P LANE OF MAX IMUM : 55 . 0 VERTICAL ANGLE OF MAX IMUM : 57 . 5 CD Figure 2-19. Light intensity polar plot. l l lu m i na nce levels are dependent on l u m inaire mounting For mounting heig hts not shown in the table, the height, and an assumed height is therefore specified for i l l u m inance conversion factor can be calcu lated from: the iso-i l lu m i n a nce diagram. As the m o u nting height is increased, light levels decrease, and while the general Conversion factor = (assumed MH/actual MH)2, shape of the pattern of l ight is u nchanged, the pattern where MH = l u minaire mounting height spreads out. The iso-i l l u minance d iagra m is therefore plotted i n terms of mu ltiples of the mounting heig ht, For any point on a roadway, distances across and along represented by the horizontal and vertical g rid l ines of the roadway a re converted into multi ples of mounting the graph. In this way, as mounting height is increased, heig ht. For example, a point 15 m d i rectly across the the iso-il l u m i na nce d ia g ra m remai n s identical, but roadway horizontal ly from the l u m i naire, when the the lux or footcandle va lue associated with each mou nting height is 10 m, l ies at 1.5 "mounting heights" conto u r decreases. A small table provided with the across. Given the across and along m o u nting height iso-il l u m ina nce diagram will l ist conversion factors to distances, the applicable lux va lue is read from the be applied to the lux or footcandle values for different iso- i l l u m i na nce diagra m . This is then m u ltiplied by mounting heig hts, as shown in Figure 2-20. the mounting height conversion factor to obta in the 2-1 5 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway and Parking Facilities I S O L UX MOUN T I NG H E I GHT 3 �I'--- - 2 0 -- u �....... -� s ...... ..... 1 E ....... \ ...... CURB L I NE s - ' � ... 1 1"- J � ..... 3 I'\ 4 ;:-r-,_ r-. ....... �r-... \ " \ l I.-" --- r-.... .,,,... - / ....�--- RATI O • / "- 2 LONG D I STANCE A MOONTING HEI GHT Explanatory N otes: 1 Numbers in this colu mn are the multiplier ratio 2 Numbers in this colu mn are the mountin g height (MH), in metres 3 The dashed lines show the CU curves ( See Rgure 2- 13 - Example Intensity Table for summary) 3 0 . 01 0 . 02 0 . 05 O.l 0.2 0.5 l 2 5 4 10 20 50 100 200 500 1000 2000 5000 Figure 2-20. Example of an iso-illuminance (in this case, isolux) diagram. 2-1 6 I'.. rl. " r'\. I ....v . / n r--... \. I'\ \ l I j v ... ,_. I .,,,... v I \ \ ).IvI ) \ ,.. I / / v ,/ - 1 0 u.: _/ � \ I ' '"' \ � ' ' \ ti.. \ \ , � � ' \ I I\ '\.. \ \ I ,\ I\. ' I \ j \ } ' ) I..,/ \ I I ' ....� .. - I '""- ...._ .. HT . - METERS 2 . 50 1 6 . 00 5 . 00 4 . 00 7 . 50 1 . 78 1 0 . 00 1 . 00 1 5 . 00 o.u 2 0 . 00 0 . 25 2 5 . 00 0.16 I \ ' \ \ ' .v 5 \ \ \ ' \E F I IINT Of UT LizA IOI \ OA�HEp ( R''ES ' ,. \ ,. - ...... . o� ' 1'- ' I.I - ...... o . �o \ - l 01 � µ. ' \ ' ' ""'" �'- ' """" !"\ � \ -\ \ \ ...... 0 so T \ --- �· � 2 - \ \ ' ' �ntin9 Hultiplie� ' \ \ ' \ \ ' \ \ ,, ,uu '.u !\.. I\. ""' ' ' ,'· I �.... ....v_ .. '/ ' --" .v R E \ , ' \ \ ' ' \ \ ' "!'I. I . """""" \ - T E -...... .. ..... � I"-.. \ \ ....... ...., .. H FOR I S OLUX 1 0 . 0 METERS N ote 2 I '] v ,..... I � v 1,..-1 � i(, 5 / / / 10000 2000 5000 6 7 Note 1 Vision and Fu ndamental Concepts i l l u m i nance va lue at the point for the design mounting optics can be considered as the l ig hting appl ication is height. (Note that this is i niti a l i l l u m inance, with no l ight designed. l oss factors applied. See Section 3.1 .6 - Light Loss Factors for additional i nformation.) Proper distribution of the light flux from l u minaires is 2.5.5 Relative and Absolute Photometry. The lighting The l ig ht emanating from the luminaires is d i rectional ly one of the essential factors i n efficient roadway l i g hting. design ca l c u l ations will use l u m i n a i re photometric control led and proportioned i n accordance with the data from either a relative-photometry report or an req u i rements for seeing and visibil ity. Light d istri butions a bsolute-photometry report, usually depending on the are generally designed for a typical ra nge of conditions light source. that include l u m i na i re mounting heig ht, transverse (overhang) location of l u m inaires, longitudinal spacing 2.5.5.1 Relative Photometry. For l u m inaires tested of l u m i na i res, widths of roadway to be effectively with relative photometry, lamp l umens are measu red. lig hted, a rrangement of l u mi n a i res, percentage of The reported initial lamp l u mens for the type of lamp l u m i na i re l umens di rected toward the pavement and being specified in the design a re used in the lighting adjacent areas, and maintai ned efficiency of the system . calcu lation. This i nformation can be obtained from the lamp manufacturer's pu blished data. When defining Lu m i naire l ig ht distribution may b e classified accord ing l a m p l u mens, it is critica l that the correct i n itial lamp to several characteristics, a mong them: l u mens be used as the basis for calcu lations. Publ ished • Longitudinal (a long-road) light distribution • Transverse (across-road) light distribution • H igh-angle (glare producing) light distribution For l u m i naires tested • U pward light distribution with a bsol ute photometry, l a m p l u m ens a re not • Backward ("house side") l i g ht distribution lamp l u mens w i l l sometimes vary s l ightly from manufacturer to man ufacturer. 2.5.5.2 Absolute Photometry. reported. (A value of -1 is entered in the l u m inaire photometric report in the Lu mens Per Lamp position, as Different transverse d istributions are available for a p laceholder on ly.) In this case, the calculations depend different street-width-to- m o u nt i n g -h e i g ht ratios, on the l u m i naire l u mens only. Therefore, it is critical that a n d d ifferent longitudinal distributions are available the photometric data used i n the calcu lations accu rately for different spacing-to-mounting-height ratios. The represent the l u m i naire specified in the design. longitudinal and transverse categories a re described i n Sections 2.6.1 and 2.6.2, respectively. The 2.6 Luminaire Classification Systems O utdoor l ig hting serves a variety of pu rposes, h i g h -a n g l e, d istribution u pwa rd, characteristics and backward a re described l i ght by the including providing light for nighttime visual activities, Lu m i naire Classification System for Outdoor Luminaires contri buting to safety and secu rity, and enhancing (LCS) and quantified via BUG (Backl ight, U pl ig ht, Gla re) the beauty of a rchitectu re, monu ments, scu l ptu re, or ratings. The LCS and BUG ratings are described briefly in landscape. Outdoor lighting also serves to i m prove Section 2.6.3. (For more information on the Luminaire d riving visibil ity on roadways. Nighttime l i g hting can Classification System, see IES TM-1 5-1 1 .) enhance social experiences and revita lize the economy of a municipa l district. However, a careful selection of Classification of l i g ht distribution in the longitudinal and l ighting equipment is critical to ensure that the positive tra nsverse categories is made based on an isoca ndela aspects of o utdoor l i g hting do not s i m u ltaneously diag ra m that, on its recta n g u l a r coord inate g rid, has create a nuisance for local residents, including humans, superimposed a series of Longitu d i na l Roadway Lines fau na, and flora. The issues of l ig ht pol l ution, glare, (LRL) i n multi ples of m ou nting height (MH), and a natura l habitat, and the nighttime envi ron ment a re best series of Transverse Roadway Lines (TRL) in m u ltiples addressed when meaningfu l data regard ing l u m inaire of m o u nting heig ht. The relationship of LRL and TRL to 2-17 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities a n actual street and the representation of such a web • MH, 2.25 MH, 3.75 MH, 6.0 M H , and 8.0 MH are shown in Figures 2-21 and 2-22. The m i n i m u m information that s h o u l d appear on such a n isocandela • Maxi m u m candela location and half-maxim u m candela trace d iagram for classification is: • TRLs located l ongitu d i n a l ly to the l u m inaire 1 .0 LRLs located tra nsversely to the l u minaire at 1 .0 • Candela l i nes equal to the nu merica l va lues of 2%, 5%, 1 0%, and 20% of the l u m inaire l u mens MH, 1 .75 MH, and 2.75 MH Ratio of Transverse Distance to Mounting Heig ht Luminai re 0 1 .0 1 .0 2.0 3.0 4.0 5.0 ( - 0- (A) Type I ) (B) Type I - 4-Way c=-o-£:1 (D) Type I I (C) Type II - 4-Way (E) Type I l l (F) Type IV (G) Type V Longitudinal Roadway Lines (LRL) Figure 2-21. Plan view of roadway coverage for different types of luminaires. 2-18 Vision and Fu ndamental Concepts HALF MAXIMUM ISOCANDELATRACE ON SPHERE SHORT DISTRIBUTION RANGE (S) \ I I I I I HOUSE SIDE I I MEDIUM DISTRIBUTION RANGE (M) STREET SIDE 1 .75 MH LRL 1 .0 MH LRL 2.75 MH LRL HALF-MAXIMUM CANDELA ISOCANDELA TRACE ON ROADWAY Figure 2-22. Diagram showing projection of maximum candlepower and half-maximum-candlepower isocandela trace from a luminaire having a Type Ill - Medium distribution on the imaginary sphere and the roadway. 2.6.1 Longitudinal Light Distribution (S, M, L). Luminaire l ig ht d istributions with maxi m u m candela emission occu rri ng at higher vertical ang les i n the longitudinal d i rection a re helpfu l i n atta i n i ng the required l u m i na nce u niformity where longer l u m inaire spacings a re used (as on residential streets and roadways with l ig ht traffic). (See Figure 2-23.) Distributions with l ower vertical a ng les of maxi m u m candela em ission are used in order to reduce system glare. This becomes more i m porta nt when u s i ng h i g h l u m e n output l u m i naires. The lower the emission angle, the closer the l u m inaire spacing should be, to attai n req uired Maximum Candlepower (see Note 1 ) Mounting Height (MH) I .. Spacing (see N ote 2) .. I Note 1 : Maxi m u m candlepower beams from adjacent l u m inaires should at least meet on the road surface. Note 2: Maximum l uminaire spacing generally is less tha n: Short Distribution: 4.S M H Medium Distribution: 7.5 M H Long Distribution: 1 2.0 MH l u m i na nce un iform ity. This applies to i ll u m ina nce as wel l . Therefore, to achieve specific l u m i nance results Figu re 2-23. Typical roadway lighting layout showing it becomes necessary as a part of any l ig hting system spacing-to-mounting height relationships. 2-19 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities design to check the l u m i nance u niformity by checking the Type I width range on both sides of the reference ratios of average l u m i na nce to m i n i m u m l u m i na nce. line that is bou nded by 1 .0-MH house-side LRL and 1 .0MH street-side LRL within the longitudinal distribution Long itudina l (along-road) l ight distributions a re divided range (short, medium, or l ong) where the point of into three g ro ups: short (S), med i u m (M), and l ong (L). max i m u m cand lepower fa lls. (See Figures 2-21 and 2-22.) Type I , Four-Way: A distribution is classified as Type I, 2.6.1 .1 Short Distri bution. A l u minaire is classified as Fou r-Way when it has fou r beams of the width defined having a short l i g ht distribution when its maxi m u m for Type I a bove. candlepower point (the direction o f maxi m u m i ntensity extended to the g round) l ies in the "S" zone of the g rid, Type V: A d istri bution is classified as Type V when the which is from the 1 .0-MH TRL to l ess than the 2.25-MH distribution has a circular sym metry of cand lepower TRL. distribution that is essentially the same at a l l latera l a n gles around the l u m i naire. 2.6.1 .2 Medium Distribution. A l u minaire is classified as having a med i u m light distribution when its maxi m u m Type VS: A Type VS l u m i naire is one where the zonal candlepower point lies i n t h e " M " zone o f the g rid, l u mens for each of the eight horizontal octants (0-45, which is from the 2.25-MH TRL to less than the 3.75-MH 45-90, 90-1 35, 1 35-1 80, 1 80-225, 225-270, 270-315, and TRL. 31 5-360 deg rees) a re within ±1 0 percent of the average zonal l u mens of all octants. The distribution is similar to 2.6.1 .3 Long Distri bution. A l u m i naire is classified as the Type V distribution but has a sq uare shape. having a long light d istri bution when its maxi m u m cand lepower point l i e s i n t h e "L'' zone o f t h e grid, which is from the 3.75-MH TRL to less than the 6.0-MH TRL. 2.6.2.2 Luminaires on Near Side of Area. The transverse d istribution classifications that deal with l u m i naires that are intended to be mou nted near the side of the area VS). to be lig hted vary as to the width of distribution ra nge Transverse l ig ht distributions (see Figures 2-21 and 2.6.2 Transverse Light Distribution (Types I on the street side of the reference l i ne. The house-side - 2-22) a re divided into two g roups based on the location seg ment of the half-maximum-candlepower isocandela of the l u m inaire with respect to the a rea to be l i g hted. trace within the l ongitud inal ra nge i n which the point Each g roup may be su bdivided with regard to the of maxi mum candlepower fal ls (short, med i u m, or long) width of the road to be l i ghted, indicated in terms of may or may not cross the reference l i ne. In general, the MH ratio. Only the segments of the half-maxim u m it is prefera ble that the ha lf-maximu m-candlepower can d l epower isocandela trace that fa l l within the isocandela trace remain near the reference line. The longitudinal distribution range, as determined by the va riable width on the street side is as defi ned: point of maxi m u m candlepower (short, medium, or long), are used for the pu rpose of esta bl ishing the Type II: A distribution is classified as Type I I when the l u m i na i re distri bution's transverse classification. street side segment of the half-maximu m-ca n d lepower 2.6.2.1 Luminaires at or Near Center of Area. The the point of maxi mum candlepower fa lls (short, medium, g ro u p of transverse distribution classifications that or l ong) does not cross the 1 .75-MH street side LRL. isocandela trace within the longitudinal range in which deals with l u m i naires i ntended to be mou nted at or near the center of the area to be l i g hted has similar light Type II, Four-Way: A d istribution is classified as a Type d istributions on both the "house side" and the "street II, Fou r-Way when it has four beams, each the width on side" of the reference l ine. the street side as defined for Type II above. Type I: A distribution is classified as Type I when its half­ Type I l l : A distribution is classified as Type I l l when the maxi m u m-candl epower isoca ndela trace l ies within street-side segment of the half-maximu m-candl epower 2-20 Vision and Fu ndamental Concepts isoca ndela trace with i n the long itud i n a l ra nge i n • The LCS utilizes existing photometric test data which the point o f maxi m u m cand lepower fa l l s (short, and can be easily reported by man ufacturers or med i u m, or long) lies partly or entirely beyond the incorporated i nto software tools. 1 .75-MH street-side LRL, but does not cross the 2.75-MH • The LCS enables desig ners to eva luate and compare street-side LRL. the distribution of l u mens for various types of Type IV: A distribution is classified as Type IV when the the l u m i naire most a ppropriate for the application. luminaire optics, thus assisting in the selection of street-side segment of the half-maxim u m-candlepower isoca ndela trace with i n the long itud i n a l ra nge i n As i llustrated in Figure 2-24, the primary solid ang les which the point o f maxi m u m cand lepower fa l ls (short, defined by the LCS a re: med i u m, or long) l ies partly or entirely beyond the 2.75- • Forward Light • Back Light • Uplight M H street-side LRL. 2.6.3 The I ES Luminaire Classification System (LCS) and BUG Ratings. The Luminaire Classification System for Outdoor Lu minaires (LCS)16 provides i nformation to l ighting professionals regarding the lumen distribution The total l u mens i n a l l zones together comprise the total l u m i na i re l u men output. within solid a ng les of specific interest. The l umens with in these solid angles a re intended to be one of the metrics used to evaluate l u m i naire optical d istribution, including the potential for light pollution and obtrusive l i g ht, but Uplight not as the only metric that should be eval uated. Light poll ution and obtrusive light result not only from the optical characteristics of the l u m inaires, but also from the application of those l u minaires within an outdoor site or roadway. A deta iled eva l uation of the lighting performance for the outdoor site should be based not o n ly on the l u m i naire optics, but also on overa l l system design, including l u minaire locations, util ization of l i g ht where it is needed, l ig hting qual ity, visual tasks, aesthetics, safety requirements, and security issues. Figure 2-24. The three primary solid angles of the The Luminaire Classification System (LCS) defi nes the Luminaire Classification System (LCS). d istribution of l i g ht from a l u m i na i re within three primary solid a ng les. These are fu rther divided i nto 1 0 2.6.3.1 I ntended Use. The LCS metrics are indicators secondary solid angles. The LCS describes the l u m i naire of optical d istri bution and a re intended to be used in l u mens for each primary and secondary solid ang le. conj u nction with the IES d istribution classifications It is based i n part on ! ES-fu nded research.11 The LCS (Type I, II, I l l, IV, V; and Short, Med i u m, Long; see Section quantifies l ight d istri bution in front of the l u m i naire, 2.6.2) for a more complete ana lysis of where the l i g ht is behind the l u m i n a i re, and a bove the l u m inaire. The distributed. system offers the following benefits: • The LCS defines the sta ndard solid ang les for As previously noted, the LCS is designed to describe the eval uation and comparison of outdoor l u minaires. l u men distribution of a n i ndividual l u m i naire. It provides the basic model from which li mits for l u mens withi n the solid a ng les by l ig hting zone and The lumens within each LCS solid angle provide data that application type w i l l be defined. can relate to an evaluation of light trespass and sky g low. 2-21 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities However, these issues relate also to the optical distribution ANS/I/ES LS-4-20, Lighting Science: Measurement of Light of light as a function of the installed characteristics, - The Science of Photometry12 for further i nformation including location of the luminaires with respect to reg a rding photometry and luminaire zonal l u mens.) property line, installed height, and spacing; uniformity of light; and reflective characteristics of the ground materials, which may contribute to light reflected into the sky. 2.6.3.3 Forward Light. Forward light describes the l u men distribution in front of the luminaire. The forward light solid angle is defined between 0 and 90 degrees vertical, and The previous I ES cutoff classifications (full cutoff, cutoff, 270 to 90 degrees horizontal, in front of the luminaire. The semi-cutoff, a nd non-cutoff) were based on lamp lumens forward light solid angle is further refined into four vertical and therefore not applicable for l u m i naires tested with secondary solid angles to evaluate the distribution of light absolute photometry, such as LED l u minaires. Since 2009, in front of the luminaire. The forward light secondary solid the cutoff classification system has been superseded by ang les (see Figure 2-26) are defined as follows: the Luminaire C lassification System (LCS). 2.6.3.2 Solid Angle References. The LCS is based Plan on IES photometric testing proced u res. Using these proced u res, a web of i ntensity val ues is m easured around a l u m inaire, creating a sphere of data points (see Figure 2-25). L u m i n a i re l u mens a re calcu lated based on the measu red intensities in specific solid angles. The term nadir refers to the point d i rectly below the l u minaire. This IES publication refers to LCS solid ___,___ oo (Directly in front of luminaire) _ _ _ _ _ _ angles based on vertical angles referenced from nadir and lateral a ng les referenced in a cou nter-clockwise direction from the front of the l u m inaire. (Refer to Sections 2 .5.3 through 2.5.5 in this document and to 90° horizonta l 90° vertica l 270° Section Nadir (directly below the l u m i n a i re) 0° horizonta l 0°(Nadir) Grade Figure 2-25. Solid angle references are based on a sphere Figure 2-26. Plan view (top) and section view (bottom) of data points around a luminaire. for forward solid angle. 2-22 Vision and Fu ndamental Concepts • Forward light low (FL): Percent l u minaire l umens • • • Back light high (BH): Percent lamp lu mens between 60 and 80 degrees vertical (or l u m i naire l u mens between 0 and 30 deg rees vertical in front of the l u m i naire. This is the l ig ht em itted that reaches the with in that solid angle) behind the l u m inaire. This is g round from d i rectly below the l u m inaire to 0.6 the light emitted that reaches the ground from 1 .7 mounting heig hts away from luminaire. to 5.7 mounting heights away from the l u m inaire. Forward light mid (FM): Percent l u m i n a i re l umens • Back light very high (BVH): Percent lamp l u mens between 30 and 60 degrees vertical in front of the between 80 and 90 degrees vertical (or l u m inaire l u m i naire. This is the light em itted that reaches the l u mens within g round from 0.6 to 1 .7 mounting heig hts away from l u m i na i re. This is the l ig ht em itted that reaches the the l u minaire. ground beyond 5.7 mounting heig hts away from Forward light high (FH): Percent l u m inaire l umens the l u m inaire. between 60 and 80 deg rees vertical in front of the l u m i naire. This is the l ig ht em itted that reaches the g round from 1 .7 to 5.7 mounting heig hts away from that solid a n g l e) Plan the 90° the l u m inaire. • behind Forward light very high (FVH): Percent l u m inaire l u mens between 80 and 90 degrees vertical in front of the l u m i naire. This is the l ig ht emitted that reaches the g round beyond 5.7 mounting heig hts away from the l u m i na i re. 2.6.3.4 Back Light. Back light describes the l u men d istribution behind the l u m inaire. The back l ight solid a n g le is defined between 0 and 90 degrees vertical, 1 80° -+-�����---­ (Directly behind l um ina ire) and 90 to 270 deg rees horizontal, behind the l u m i naire. This solid angle can be used to eval uate the potential for l ig ht trespass when l u minaires are located near the property l i ne. When l u m i naires are located in the i nterior 270° of a site, the eva l uation of a l u m inaire distribution may or may not consider the back light relative to offensive l ight. The back l ight solid angle is fu rther refined into four vertica l secondary solid angles to eva l uate the distribution of l ight behind the luminaire. The back l ight secondary solid angles (see Figure 2-27) a re defined as Section follows: • Back light low (BL): Percent lamp l u mens between 0 and 30 degrees vertical (or l u m i naire l umens 80° within that solid ang le) behind the l u m i na i re. This is the l ig ht em itted that reaches the g round from directly below the l u m i naire to 0.6 m o u nting heights away from l u m i naire. • Back light mid (BM): Percent lamp l u mens between 30 and 60 degrees vertical (or l u m i naire l umens within that solid angle) behind the l u m i naire. This is G rade 0° ( N a d i r) the light emitted that reaches the g round from 0.6 Figure 2-27. Plan view (top) and section view (bottom) for to 1 .7 mounting heig hts away from the luminaire. back light solid angle. 2-23 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 2.6.3.5 Uplight. Uptight describes the l u men distribution • Uplight low (UL): Percent lamp l u mens between above the l u minaire. The u p l ig ht solid angle is defined 90 and 1 00 degrees vertical (or l u m inaire l u mens between 90 and 1 80 degrees vertical, and 0 to 360 with in that solid angle) 360 degrees a round the deg rees horizontal, around the entire l u m i naire. U pl ig ht luminaire. Light emitted at or slightly a bove 90 is a contributor to sky g l ow. The overal l i m pact on deg rees wil l affect sky glow as seen by a n observer sky g l ow is a function of the angle of light a bove the far from the city. horizontal, atmospheric scatteri ng of the l ight, and • Uplight high (UH): Percent lamp l umens between geographic l ocation.13 The u pl ig ht solid angle does not 1 00 and 1 80 deg rees vertical (or l u m i naire l u mens account for the directional im pact on sky g l ow nor does with in that solid angle) 360 degrees a round the it qua ntify the i m pact from light reflected from ground l u m i na i re. Light em itted at ang les a bove 1 00 su rfaces and adjacent structures. deg rees w i l l affect sky g l ow as seen from within the city. The uplight solid angle is fu rther refined into two vertical secondary solid a ngles, to evaluate the distribution of l ig ht at or near horizontal and that directly above the l u m i naire. The u pl ig ht secondary solid angles (see Figure 2-28) are defined as follows: 2.6.3.6 BUG Rati ngs. Based on its l u me n output in the various Backlig ht, Upl ight and Glare zones, a l u m i na i re is assigned a BUG rating, which the l ighting designer can use as a n initial means of eva l uating and com paring l u m inaires for potential i nclusion i n a desig n . Plan A BUG rating may be used t o eva l uate luminaire optical performance related to the potential for l ig ht trespass, sky g l ow, and high-angle brig htness contro l . The BUG ratings are based on zonal lumen calcu lations for the secondary solid ang les defined above and i n ANSl/IES TM-15-20.14 1 80°+------+•---+ 0° 2.6.3.7 Summary. The LCS provides a useful tool to eva l uate the overal l d istribution of lu mens into key solid angles. However, the LCS should not be the sole proced u re used i n eva l uating lighting quality. There are other considerations that need to be evaluated, 270° including (but not l i m ited to) i l l u m i na nce l evels, u n i formity, l u m i na nce, glare, aesthetics, color, energy Section efficiency, cost, safety and security, distribution of light onto a reas where it is needed, and specifics appropriate UH High for the intended application. Add itional i nformation on the Luminaire C lassification System may be found in ANSl/IES TM-1 5-20.14 2.6.4 Variations and Comments. With the variations in roadway width, type of su rface, l u minaire mounting heig ht, and spacing that may be fou nd i n actual practice, there can be a large n u m ber of "ideal" intensity d istributions. 0° (Nadir) Grade For practical a p p l i cations, however, a few types of transverse distribution patterns may be preferable to many complex a rrangements. This Figure 2-28. Plan view (top) and section view (bottom) simpl ification of distribution types will be more easi ly for u plight solid angle. understood, and conseq uently there w i l l be g reater 2-24 Vision and Fu ndamental Concepts assurance of proper instal lation and more-reliable Other pu rposeful variations from the d istri butions mai ntenance. specified may be advantageous from time to time for special applications. 2.6.4.1 U pward Tilt. When l uminaires are tilted u pward, it raises the angle of the street-side l ight distribution. 2.6.4.4 Multiple-Lu minaire Arrangements. For high­ Features such as BUG rating and transverse-d istribution mast i nsta l lations i nvolving m u ltiple l u m inaires on one classification can be changed apprecia bly. When the ti lt structure or su pport and where a l l of the l u m i naires is planned, the l u minaire should be photometered and have the same photometric distribution and orientation the light distribution classified for the position in which in the a pplication, the entire group of l u m inaires may be it will be i nsta l led. considered as a single composite l u minaire for purposes of determining distribution type or maxi m u m candela 2.6.4.2 Coverage. Types I, II, I l l, and IV transverse l ig ht va l ue. Photometric data may be su ppl ied i n this form. d istri butions should vary across tra nsverse roadway l i nes other than that which includes the maxi m u m candlepower, in order t o provide adequate coverage of the rectangular roadway area i nvolved. The forward reach of the transverse d istri bution req u i red to adequately cover a typica l width of roadway varies with the longitudinal light distribution as shown by the TRL (transverse roadway l ine). For a l u m inaire with a longitudinal reach to TRL 4.5 MH, the extent of the transverse l ight distribution is obviously less than that a l lowed by a l u m inaire with a long itudinal reach to TRL 3.0 MH or TRL 2.0 MH. 2.6.4.3 Consistency. For typical roadway conditions, it is desirable to achieve very closely the l i g ht d istributions prescribed, for consisten cy. Va riations from these d i stributions a re expected when necessa ry. Several exa m ples of these exceptions are: • Luminaires that provide broad Type I or Type I I d istributions a n d which project t h e maxi m u m cand lepower at a lower angle t h a n specified • Directional lighting for one-way streets and d ivided hig hways where the l ig ht projected in the d i rection of traffic is substantially reduced in the high vertica l angle • Linear-sou rce l u m i naires oriented para l lel to the street for reduced g lare and increased utilization • Luminaires at low mounting heig hts • Types IV and V l u minaire distributions with extra u pward l ight for i ll u m i nati ng building fronts • "Offset mounting" style l u minaires desig ned to be l ocated at a lateral d istance from the area to be l i ghted 2-25 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities R E F E R E N C E S FOR CHAPTER 2 1. I l l u m i nating Engineering Society. ANSl/IES LS-1 -20, Lighting Science: Nomenclature and Definitions for I l l u m i nating Engineeri ng. New York: I ES; 2020. Online: https://www.ies.org/standards/definitions/. (Accessed 2021 J u l 29). 2. H ubel DH. Eye, brain, and vision. Scientific American Libra ry. 1 988. 3. I l l u m i nating Engineering Society. LS-7-20, Lighting Science: Vision - Eye and Brain. New York: I ES; 2020. 4. Tyukhova, Y. Discomfort glare from small, hig h-l u m i nance l i g ht sources in outdoor nighttime environments. In: Architectural Engineering - Dissertations and Student Research. Lincoln, Neb.: U niv of Nebraska; Dec 201 5. Online: https://digita lcommons.unl .edu/cgi/viewcontent.cgi?article=1038&context=archengdiss (Accessed 2021 Apr 9). 5. International Commission on I l l umination. CIE 1 8.2:1 983, The Basis of Physical Photometry. Vienna, Austria: CIE.; 1 983. 6. International Commission on I l l u mination. CIE 41 : 1 978, Light as a True Visual Quantity: Principles of Measu rement. Vien na: CIE; 1 978. 7. International Com m ission on I l l u mination. CIE 8 1 :1 989, Mesopic Photometry: H istory, Special Problems and Practical Solutions. Vienna: CIE; 1 989. 8. Kooi FL, Alferd inck JWAM, Post D . I n : H u m a n Factors in Desig n, Safety a n d Management. Maastricht, Netherlands: Shaker; 2005. 9. Demography of the U nited States. Wikipedia. https://en.wiki pedia.org/wiki/Demogra phy_of_the_Un ited_States. (Accessed 2021 Apr 9). 1 0. l l u minating Engi neering Society. ANSl/IES LM-63-19, Standard File Format for Electronic Transfer of Photometric Data. New York: I ES; 201 9. 1 1 . McColgan M, Bullough J, Van Derlofske J, Rea M. LESS: Luminaire Eva l uation and Selection System. New York: I l l u m i nating Engineering Society; 2005. 1 2. I l l u m i nating Engineering Society. ANSI/I ES LS-4-20, Lighting Science: Measurement of Light - The Science of Photometry. New York: I ES; 2020. 1 3 . Cinzano P, Diaz FJ. The a rtificial sky l u minance and the emission angles of the u pward l ig ht flux. J Italian Astronom ical Soc. 2000;7 1 (1 ):25 1 . 1 4 . I l l u m i nating Engineering Society. ANSl/IES TM-1 5-20, Technica l Memorandum: Luminaire Classification System for Outdoor Luminaires. New York: I ES; 2020. 2-26 Ca lcu lations Cha pter 3 CO N T E N TS 3.1 Calcu lation Elements . . . . . . . . . . . . . . . . . . . . . . 3-1 3.3.5 Road Geometrics . . . . . . . . . . . . . . . . . . . . 3-1 3 . 1 .2 Road Type . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 3.1 .3 Pedestrian Conflict . . . . . . . . . . . . . . . . . . 3-1 Pavement llluminance . . . . . . . . . . . . . . . . . . . 3-25 3.1 .4 La mp or Lu minaire Lumens . . . . . . . . . . 3-1 3.4.1 Form ulas and U nits . . . . . . . . . . . . . . . . 3-26 3. 1 .5 Pavement Classification . . . . . . . . . . . . . 3-1 3.4.2 S u m mary of Pavement 3.1 .6 Light Loss Factors (LLF) . . . . . . . . . . . . . . 3-2 3 . 1 .6. 1 Mai ntenance Factors (MF) . . . . 3-3 3 . 1 .6.2 E q u i pment Factors (EF) . . . . . . . 3-6 3 . 1 .6.3 Luminaire-Point Combinations . . . . . 3-21 3.4 Calculation of Roadway l l lu mina nce Data . . . . . . . . . . . . . . . . . . . 3-26 3.5 3.6 Uniformity Ratios . . . . . . . . . . . . . . . . . . . . . . . . 3-26 Two Metrics of Glare in Roadway Lighting. 3-26 3.6.1 Deter m i nation of LLF 3.1 .7 Veiling Lumina nce . . . . . . . . . . . . . . . . . 3-26 3.6. 1 . 1 for Existing Instal lation . . . . . . . 3-7 3.2 Example of Determining Va lid 3. 1 . 1 Lu minaire Position and Orientation . . 3-7 3 . 1 .8 I m pact of Vehicle Headlights . . . . . . . . 3-7 3 . 1 .9 Change in P hysical Surrou ndings . . . . 3-7 3.1 . 1 0 I m pact ofTrees on Lighting . . . . . . . . . . 3-7 3.7.1 Ca lcu lating Ta rget Lumina nce . . . . . 3-28 3 . 1 . 1 0. 1 General Considerati o n s . . . . . . 3-9 3.7.2 Ca lcu lating Ta rget Visibility . . . . . . . . . 3-30 3 . 1 . 1 0.2 Des i g n Consi derations . . . . . . . 3-9 3.7.3 Sum mary of Data . . . . . . . . . . . . . . . . . . 3-30 3 . 1 . 1 0.3 Des i g n Data . . . . . . . . . . . . . . . . 3 - 1 0 Roadway Lighting Metrics - 3.6.2 3.7 3.8 3.9 Threshold I ncrement (Tl) . . . . . . . . . . . 3-27 Small Target Visibi lity (STV) . . . . . . . . . . . . . . 3-28 . Vertical llluminance . . . . . . . . . . . . . . . . . . . . . . 3-30 Tu nnel Calcu lations . . . . . . . . . . . . . . . . . . . . . . 3-31 General I nformation . . . . . . . . . . . . . . . . . . . . . . 3-1 0 3.9.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 1 3.2 . 1 3.9.2 Selection of a Grid for Tu nnel Assu med and Sta ndard Conditions . 3-1 1 3.2.2 Accu racy of Calculations . . . . . . . . . . . 3-1 1 Lighting Ca lcu lations . . . . . . . . . . . . . . . 3-32 3.2.3 Selection of a Grid and Luminaire 3.9.2.1 Location Geometry for Calcu lations. 3-1 1 3.3 Effect o f Age o n Vei l i n g Lu m i nance . . . . . . . . . . 3-27 3.2. 3 . 1 Straig ht Roadway Areas . . . . . 3-1 1 3.2.3.2 Pedestrian Wal kways . . . . . . . . 3 - 1 5 3.2.3.3 C u rved Roadway Secti o n s . . . 3 - 1 5 3.2.3.4 Traffic Conflict Areas . . . . . . . . 3-1 5 3.2.3.5 C u l-de-Sac . . . . . . . . . . . . . . . . . . 3-1 5 3.2.3.6 Mid block Crosswa l k . . . . . . . . . 3 - 1 5 3.2.3.7 I ntersection . . . . . . . . . . Pave ment - L u m i nance . . . . . 3-32 3.9.2.2 3.9.2.3 3.9.3 The r-Ta bles . . . . . . . . . . . . . . . . . . . . . . . . 3-1 6 3.3.2 Pavement Classification Systems . . . . 3-21 3.3.3 Form ulas and U n its . . . . . . . . . . . . . . . . 3-21 3.3.4 Sum mary of Pavement Tu n n el Wal l s - l l l u m i nance . . 3-34 Computation of the Direct Component . . . . . . . . . . . . . . . . . 3-34 3.9.4 Discretization of the Tu nnel Su rfaces . . . . . . . . . . . . . . . . . . . . 3-34 3.9.5 Pavement Luminance . . . . . . . . . . . . . . . . . . . . . 3-1 6 3.3.1 C u rved Tu nnel Pavement - l l l u m i na n ce . . . . 3-34 . . . . . . . 3-1 6 Calcu lation of Roadway Strai g h t Tu n nel Computation of the I n d i rect Component of II l u m i na nce . . . . . . . . . 3-35 3.9.6 Computation of Surface Element 3.9.7 Computation of the I n d i rect Lumina nce and Reflected Intensity . . . 3-36 Component of Vei l i ng Luminance . . 3-37 Luminance Data . . . . . . . . . . . . . . . . . . . 3-21 Additional Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-39 References for Chapter 3 . . . . . . . . . . . . . . . . . . . . . . . 3-41 Chapte r 3 Ca lculations T his chapter is divided into two main seg ments. The first (Section 3.1) covers the various elements of the roadway or tunnel environment that contribute to roadway l ig hting design and a n a lysis calcu lations. The second major seg ment (Sections 3.2 through 3.9) describes the va rious types of roadway lighting metrics and provides instruction i n thei r cal c u lation. 3.1 Calculation Elements Lighting. Roadways a re divided into two main types: Lighting specifications vary according to several factors highways and streets. Hig hways are fu rther subdivided related to the nature of the roadway and its occupants. i nto freeways and expressways. Streets a re fu rther This section provides backg round on these factors, subdivided as major, collector, and loca l . including: • Road or tunnel geometrics • Road type and potential for pedestrian conflict 3.1 .3 Pedestrian Conflict. Where pedestrians may be present, the specifications for a particular road type are subdivided in accordance with the level of pedestrian • La m p l u mens • Pavement classifications • Light l oss factors • Luminaire position and orientation • I m pact of vehicle head lights Med ium, and Low categories. These categories define • I m pact of trees on lighting the potential for pedestrian conflict, based on the l i kely conflict or activity. These levels a re usually associated with the form and amount of nig httime activity in the abutting land a rea. The three categories are defined in Chapter 11 - Street Lighting, and include High, a m ou nt of pedestrian activity i n or near the road at 3.1 .1 Road Geometrics. Road geometrics wil l have n i g ht. a major im pact on the lighting calculations. The road geometric i nformation needed to prepare a l i g hting 3.1 .4 Lamp or Luminaire Lumens. The l i g hting design ca lculation i ncludes: calculations will use l u minaire photometric data from • Nu mber and width of traffic lanes • Any horizontal and vertical cu rves • Width and locations of sidewa l ks and shoulders • Size and location of media ns, isla nds, stationing, bridge structu res, culverts, overhead and u nderg round util ities, and sensitive off-rig ht-of­ way areas • • either a relative-photometry report or an a bsolute­ photometry report, usually dependi n g on the l ig ht sou rce. (Refer to Sections 2.5.3 through 2.5.5 for more information on l u m inaire photometry.) 3.1 . 5 Pavement Classification. The calcu lation of either pavement l u m inance or Small Target Visibil ity (STV) req u i res information a bout the directional surface Locations of d riveways, crosswa l ks, rai l crossings reflectance characteristics of the pavement. Stud ies and intersections have shown that m ost common pavements can be For tunnels: dimensions; su rface characteristics; grou ped i nto a l i m ited n u m ber of sta ndard road surfaces divided or und ivided having specific reflectance characteristics. These data have been experimenta lly determined and presented i n Al l of this i nformation w i l l be req u i red to u nderta ke r-tab les. (See Section 3.3.1 .) roadway lighting calcu lations. For pu rposes of this Recom mended Practice, pavement 3.1 .2 Road Type. The type of road is a primary factor reflectan ce cha racteristics fol l ow the I nternatio n a l that influences the lighting specification. The categories Commission on I l l u m ination (CIE) F o u r Class system.1 are defined in Chapter 1 0 - Highway and Interchange A description of road su rface classifications is g iven in 3-1 ANSl/IES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Table 3-1 . The classification is based on the specularity 3.1 .6 Light Loss Factors (LLF). These include multiple of the pavement (51), and a sca l i ng factor (Qo) as factors, which usually change with time after installation determined by the overa l l "lig htness" of the pavement. and may be combined into a single m ultiplying factor for The normalized Oo is g iven in Table 3-1 for each of the inclusion in calculations. The equ ipment factor, EF, is the pavements described. Greater accuracy in predicting exception to this. Each LLF component is control led and Visibil ity Level (VL) and pavement l u minance can be evaluated separately. Many of these are controlled by the achieved by evaluating specific pavements as to their selection of equipment (equipment factors), and many 51 ratio and specific Oo and then choosing the correct others are controlled by planned maintenance operations r-table. The 57 ratio and specific Oo for a pavement can (maintenance factors). A few are beyond the control of be determined in one of two ways: 1) a core sample can the lighting system owner or operator and depend on be removed from the pavement and photometrica l l y actions of others, such as the system voltage regulation tested b y a q u a l ified laboratory; or 2 ) a field eva l uation or the control of emissions into the atmosphere. It is, ca n be made.2 Actual pavement reflectance a n d however, the task of the system designer to determine specularity will vary with pavement age and wear. and apply a realistic LLF to all design calculations. The va lue of Q0 provided in Table 3-1 represents the The total light loss factor is obtained by multiplying a l l average l u m inance coefficient. The total hemispherical t h e contributing factors, a s described in t h e fol lowing reflectance of the su rface is determined by mu ltiplying the Q0 value by n : Oo x n = tota l hemispherical reflectance. • Concrete su rfaces (R1) with a Oo of 0.1 have a total hemispherical reflectance of 3 1 % • • Asphalt su rfaces ( R 2 a n d R3) with a Q 0 of0.07 have a sections. Where losses are believed to be reasonably small and the factor is essentially 1 .0, they may be omitted. Otherwise, those factors (as well as a ny other potentially contri buting factors) should be estimated based on experience at similar locations using similar total hemispherica l reflectance of 22% eq u i pment and maintenance proced u res. I n all cases, a Asphalt su rfaces ( R4) with a Oo of 0.08 have a total light loss factor should be used that at least considers hemispherical reflectance of 25% the LLD and the LDD. At this poi nt, if it is found that the total l ig ht loss factor is excessive it m ig ht be desirable In computing l u m i na nce leve ls, the d i recti onal reflectance characteristics of the su rfaces are used in to reselect the l u m i naire a nd/or l a m p, or modify the cleaning a nd/or maintenance sched u le. the calcu lations. These have been measu red and are reported by CIE and IES in the form of r-tables (see For exa mple: LLF Section 3.3.1). a l l factors are usually � 1 .0) = LLD x LDD x MF x LATF x BF (where Table 3-1 . Road Surface Classifications Mode of Class Oo* Description Rl 0.1 0 Asphalt road s u rface with a m i n i m u m of 12 percent of the agg regates composed of Reflectance Portland cement concrete road su rface. Mostly diffuse artificial brightener (e.g., Synopal) agg regates. (Examples: labradorite, qua rtzite) Asphalt road s u rface with an aggregate composed of a m i n i m u m 60 percent g ravel R2 0.07 (size greater than l cm). Mixed (diffuse a nd Asphalt road s u rface with 10 to 15 percent artificial brightener i n agg regate mix. (Not specular) normally used i n North America) R3 0.07 R4 0.08 Asphalt road s u rface (reg ular and carpet seal) with d a rk agg regates (e.g., trap rock, blast furnace slag); rough texture after some months of use (typical hig hways). Asphalt road s u rface with very smooth texture · Table note: See Section 3.1 .5 for a discussion of Q _ 0 3-2 Sl ightly specu lar Mostly specu lar Calculations 3.1 .6.1 Maintenance Factors (MF). The resu lt of time­ dependent depreciation effects shall be considered in the initial design. Regular maintenance is particularly important with regard to energy conservation and future performance of the system. Once maintenance plans are incorporated into the design, they should be carried out as specified or the system will not perform as expected. 3. 7.6. 7.7 Lamp Lumen Depreciation (LLD). �QI 90 1 00 ... c .,, c QI ... c "jij :::E c QI E :I ...I 80 70 60 so 5,000 1 0,000 D u ring the lifetime of most lamps, their l u men output g radually diminishes. This g radual reduction in l ig ht output with burning time is called lamp lumen depreciation (LLD). 1 5,000 20,000 25,000 30,000 Life (Hours) Figure 3-la. Lumen maintenance for several metal halide lamps. Actual mortality curves are available from the various lamp manufacturers. lllr:::::� :: ----:----- (© I l l um i nating Engi neering Society) I nformation about the chosen lamp or LED light source and its l u men depreciation are ava ilable from lamp 1 00 manufacturers' tables and g raphs. Rated average useful life should be determined for specific hours per start. Lamp-lumen mai ntenance curves represent percentages of "initial" l ig ht output (first 1 00 hours) or rated l ight output at a ny specific operating time. The life test for H I D lamps is based of 1 0 hours or more per start on ballasts of specified electrical characteristics. � � QI ... c .,, c QI ... c 'jij :::E c QI E :I ...I 80 60 1 40 l 20 Low End of Range When applying these cu rves as a reference, the user sho u l d be aware that some or a l l of the fol lowing factors may change the resulta nt initial and maintained light 0 0 20 t 40 60 1 00 Figure 3-l b. Typical lumen maintenance for • The l ight source position i n the l u m inaire high pressure sodium Lamps. (© I l l u m i nating • The Eng i neering Society) difference 80 Percent of Rated Life (%) output characteristics from those shown (see Figures 3-1 a, 3-1 b, 3-1c): High End of Range in the life a n d m a i ntenance characteristics of the lamp to be used as compared • to those shown. For example, the 400-watt H I D cu rrent is pri m a rily responsible for l ower l u men lamps in Figure 3 - 1 a and 3-1b mai ntenance and rated l ife (see Figure 3-1 c). For H I D: 0 Lamp current crest factor' for the type of bal last operating time over which a n LED l ig ht source maintains to be used 0 The rated l umen-maintenance l ife of an LED is the elapsed The range of the supply voltage as compared to the a llowable variation swing i n the input voltage a given percentage of its i nitia l l ig ht output. It is defined as Lp where p is the percentage val ue. For exa m ple, L10 is the time (in hours) when the l ight output from the of the bal last LED has d ropped to 70 percent of its initial output. The For LED sou rces, operation u n der h i g her than manufacturer's recommended temperature or driving · Lamp cu rrent crest factor is defined as the ratio of peak value to RMS va lue of a cu rrent waveform. time when the rated l u men maintenance l ife of an LED light source is reached is dependent on many variables, including the operating temperature, the d rive cu rrent, a n d the technology and materia l s used to construct the products. As such, the lumen mai ntenance of LEDs can 3-3 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 70,000 r 1 .0 60,000 0 c ::::!. .. 0 .. � S0,000 :; 0 ;. 40,000 + + u IQ u.. c 0 QI E 30,000 ·.;::: QI ... :J 20,000 '.;::: IQ ·;:; 10,000 30 40 so 60 70 80 90 100 1 10 1 20 1 30 140 l SO Junction Temperature (°C) Figure 3-1c. LED lifetime versus junction temperature. (© Illuminating Engineering Society) Figure notes: (Expected Bso, L70 lifetimes for AllnGaP* (e.g., amber, red-orange, and red) LED packages as a function of junction temperatu re, and for different drive currents. (Bso, bo) is the time to when either 50% 0.9 0.8 0.7 QI .. c. QI c 0.6 .. .. 0 Very Clean +--Clean + QI .. 'iii 0.5 + :I ...I 0.4 + c ·e 0.3 0 2 3 4 5 6 7 8 Exposure Time in Years of the population is expected to have either failed (no longer emit lig ht) (Bso), or degraded by more than 30% from initial lumen output (b0). Note that these curves vary considerably with LED package and these data should not be generalized. Note that these curves vary considerably with LED package and these data should not be generalized. * Al u m i n u m/ind i u m/ga l l i u m/phosphorus vary not only from man ufacturer to man ufacturer, but also between different LED package types produce by a single manufactu rer.3 3. 1.6. 1.2 Luminaire Dirt Depreciation (LOO). In addition to Select the appropriate curve in accordance with the type of ambient as described by the following examples: Very Clean - No nearby smoke- or dust-generating activities and a low am bient contaminant level. Light traffic. Generally li mited to residential or rural a reas. The ambient particulate level is no more tha n 1 50 micrograms per cubic meter. Clean - No nearby smoke- or dust-generating activities. Moderate to heavy traffic. The ambient particulate level is no more than 300 micrograms per cubic meter. Moderate - Moderate smoke- or dust-generating activities nearby. The ambient particulate level is no more than 600 micrograms per cubic meter. Dirty - Smoke or dust plumes generated by nearby activities may occasionally envelope the l u minaires. Very Dirty - As above but the lumi naires are commonly enveloped by smoke or dust plu mes. l a m p l u men depreciation over time, d i rt accu m u lates Figu re 3-2. Luminaire dirt depreciation (LDD) factors for on both the inside and outside of the refractor, on non-LED sources. (© I l l u m i nating Engineering Society) the inside of the l u m inaire reflector, and on the lamp. This dirt accu mulation is responsible for a n additional An estimation of LDD for LED l u minaires can be made reduction in l u minaire l ig ht output and is known as from Figure 3-3. Dirt depreciation curves a re shown luminaire dirt depreciation (LDD). for a l i mited nu mber of LED luminaires with g lass or acrylic molded outer optics, i ndividually molded acrylic The LDD for non-LED sources can be determined by inner optics (diameter a pproximately 10 to 15 m m), and estimating the dirt category (very clean, clean, moderate, la rge i ndividually molded acrylic inner optics (diameter dirty, or very dirty) from definitions given in Figure 3-2. a pproximately 25 m m). From the appropriate dirt condition curve in Figure 3-2 and the proper elapsed time in years of the assumed As noted in the caption, correlation factors for three of the cleaning cycle, the LDD factor is then selected. The dirt fou r optical configu rations tested are poor. Correlation of accumulation is assumed to be on the exterior of the a curve to data is represented by the R2 va lue. For example, luminaire and the interior of the light-transmitting portion. an R2 value of 0.3674 means that the cu rve represents 3-4 Calculations Average Dirt Depreciation Rate vs. LED Optic 1 1 0.0% 60.0% + 50.0% +-----+-----1--1--+---+ 2 7 4 10 0 3 8 5 6 9 Age, yrs. Linear (Ind ivid ual Molded Acrylic) Linear (Molded Acrylic) Linear (Large Molded Individual Acrylic) Linear (Molded Glass) Figure 3-3. Average dirt depreciation rate as a function of age for LED luminaires with various glass or acrylic inner optics. Correlation factors: molded acrylic R2 = 0.3674; molded glass R2 = 0.9963; individual molded acrylic R2= 0.273. The availability of lifetime data for all of the optic types was limited due to the evolution of the technology and a paucity of installed systems with sufficient burning time. There was sufficient data for the individual molded acrylic optics (IMA) to confirm that a simple linear fit with an intercept of 1 00% at zero years is statistically significant and was superior to other simple forms such as a logarithm or exponential decay. The slope for the IMA optics was -2.5% ± 0.7%/year. The slope for the molded acrylic optics was -1% ± 0.4%/year. The slopes for the molded glass (MA) and large molded individual acrylic (LMIA) were -2.3%/ year and -3.8%/year, respectively. There were insufficient data for these two last luminaire types (two or fewer age values) to compute uncertainties for the slopes. It should be noted that the figure shows a projection of the curves to 8 years, where no system was measured beyond a 7-year period. (Sou rce: IES RES-1 -1 64) 37% of the data and does not describe 63% of the data. study4 suggest an effect, but the correlation is poor. Therefore, the cu rves should be used carefu l ly. More More research is needed to determ ine the i m pact study is warranted to better determine the relationship of d i rt depreciation upon u niformity. The referenced between dirt depreciation a nd LED optics, luminaire study does reinforce the importance of a l u m i naire optics, age, and environment for LED roadway lighting. mai ntenance program for clea n i n g l u m i n a i res to maintain the i ntegrity of the design. The referenced report and associated g raph shown in Figure 3-3 are based u pon research com pleted i n 201 6. 3. 7.6. 1.3 Lamp Burnout Factor. Because LED roadway products are rapidly evolving, needing replacement wil l vary in q ua ntity, depending the LDD cu rves may not represent cu rrently ava i lable on the kinds of lamps and the relamping program products. Manufactu rers should be consu lted for LDD used. Man ufacturers' lamp morta l ity statistics should cu rves that that a pply to their specific products. be consulted for the performance of each lamp type Bu rned out l a m ps so that the num ber of burnouts can be determined Light pattern changes over time due to dirt depreciation before the time of pla nned replacement is reached. For will affect the u n iformity. The data from the referenced applications where maintai ned roadway i l l u m ination is 3-5 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities critical, a periodic check of lamp performance is needed. req u i re 1 to 5 m i n utes; and metal halide (MH) la mps can This can be accompl ished by a nighttime d rive-by take 10 to 15 m i nutes. Special lamps and instant-restrike or other method of monitoring lamp and l u m inaire devices may be ava ilable. (Refer to manufacturers' data.) operation. Many LED sources use power supplies that sense 3.1 .6.2 Equipment Factors (EF). Light loss factors the incoming voltage and supply the correct output that are not dependent on time relate mostly to the cu rrent to the LEDs. The input voltage can "float" over characteristics of the specific equi pment selected. While a broad ra nge of voltages (consult specific equ ipment some might not be correctable, it is possible that one or man ufactu rer) and is not subject to brown-outs or more can have a n important effect u pon the l ig ht level "re-strike" issues as d ischarge lamps a re. produced. Care should be taken in selecting eq u i pment appropriate to the service conditions. Electronic b a l lasts and power supplies a re often designed to operate over a wide ra nge of i n put The voltages and automatica l l y sense the voltage appl ied. It effect of a mbient tem perature on the output of some important to note that the l ower the input voltage, the light sou rces can be considerable. Each particular higher the i nput cu rrent. 3. 7.6.2. 7 Luminaire Ambient Temperature Factor. l i g ht s o u rce- l u m i n a i re com bi nation has its own distinctive characteristic of l ight output versus a m bient 3. 7.6.2.3 Ballast Factor. Ballast type can affect the actual temperature. To apply a factor for l ig ht loss due to versus rated l ig ht output of lam p-ballast com binations. a mbient tem peratu re, the designer should know the This l ight loss component is known as the bal last factor. hig hest and lowest temperatures expected and should Certain circuits can m i n im ize line voltage variation, have data showi ng variation i n l i g ht output with others can m i n i m ize lamp tolerances, and still others cha nges in ambient tem perature for the specific light can com pensate for l a m p aging. Photometric data source in the specific l u m inaire to be used. are based on rated lamp output under laboratory conditions. Good l ig hting design w i l l account for the Line voltage above issues and m i n im ize their effects on the lighting variations of as little as plus or minus 5% may affect system performance with proper bal last selectio n . 3. 7.6.2.2 Voltage to Luminaire Factor. the proper operation of a l l l a m ps. Proper power sou rce T h e ballast man ufacturer should be consulted for data and circuit design can m i n im ize voltage reg u lation rega rding the factors for their product and the l ig hting problems. Selection of regulated-output ballasts for calculations should incorporate these factors. arc d ischarge lamps w i l l ensure reasonable l ight output even with plus or m i n u s 1 0% variation in l i ne voltage. Note: Bal last factor does not apply to l u minaires with With su bstandard line voltage, reactor ballasts produce LED sources. a much g reater red uction in l i g ht output tha n do Su rface regulated ba l lasts. Line voltage above the standard w i l l 3. 7.6.2.4 Luminaire Component Depreciation. i ncrease l ig ht output b u t shorten lamp life. depreciation results from adverse changes in meta l, Voltage should be checked with load on at point of utilization. pai nt, plastic components, and gaskets, all of which can red u ce l i g ht output. Lam p instabil ity or extinction can resu lt ifthe line voltage fal ls below a bal last's rated input req u i rements. Even a Because of the complex relationsh ip between the light momentary voltage d rop, d u e to routine switch ing by control l i ng e lements of l u m i naires using more than the util ity, can cause a rc tube extinction in arc d ischarge one type of material, and since l u m i n a i re surfaces lamps. Before a conventional arc discharge lamp can can react differently to various atmospheres to which re-ign ite, it needs to cool sufficiently to a l low re-striking. they a re exposed, these losses can be very difficu lt to Restrike time depends on va rious operating factors. In predict. Deterioration of the l u minaire reflector or its general, low pressure sod ium (LPS) lamps restrike in lens wil l have the g reatest effect on its l ight output. one m i n ute or less; high pressure sod ium (H PS) lamps Some of these deterioration issues may be reduced 3-6 Calcu lations with scheduled maintenance. This maintenance should onco m i n g headl ights w i l l i n c rease disability g l a re.) be considered i n the design. (See Chapter 9 for further Streetl ig hts may not be necessary for driver vision on discussion of l ig hting system mai ntenance). such roads, except i n commercial areas with high levels of a m bient or stray lig ht, or other a reas with higher 3.1.6.3 Determination of LLF for Existing Installation. traffic volume, pedestrians or cycl ists. Fol lowing this Occasionally, it m ig ht be desirable to determine the recommendation may provide for safe vehicular traffic LLF for a n insta l lation that has been in service for but does not address pedestrian visual needs. a n u m ber of years. The process is relatively simple and is made much more effective if a few randomly Headlights may be inadequate for detection of objects selected l u m inaires have been photometered prior to at higher vehicle speeds. It is known that at higher insta l lation, as described in Section 3.2.2 - Accuracy speeds the safe sight stopping distance can exceed of Calculations. A few randomly selected l u minaires the visual detection d istance provided by l ow-beam should be removed in their "as is" condition and hea d l i g hts.5•6.7 photometered i n that condition. Each l u m i naire should then be restored as closely as possi ble to its original Com puter m odel i n g condition i n a step-by-step process, photometering ava i lable photometric fi les for low-beam headlig hts, the l u m i naire between each step. Such a proced u re to determine when headlights a lone wou ld provide might be: a) replace lamp; b) clean inside of l u m inaire; sufficient i l l u m ination to meet the req uirements of this has been performed, using c) clean outside of l u m inaire; d) operate at rated voltage Recommended Practice (see, for example, Figures 3-4a as well as fiel d measured voltage; and e) compare thro u g h 3-4d). The parameter eval uated in the a n a lysis with photometered resu lts when new. Photometry in was the vertical i ll u m i na nce criterion for the pedestrian this example cou ld be as sophisticated as sending the areas adjacent to the roadway. l u m i na i re to a commercial laboratory or as simple as measuring the nadir i ntensity with a photoce l l mou nted Based on the a nalysis, it appears that vehicle head l i ghts in a baffled black box. By using such a procedu re, the alone may meet the lighting req u i rements for roadways va lidity of an assumed LLF can be checked and the slow with speeds below 50 km/h (approximately 30 m i/h) and permanent deterioration described in Section 3.1 .6.1 with little or no pedestrian activity. Because this was a l i m i ted analysis, based on computer modeling, and can be determined. many va riables are i nvolved in the decision to provide 3.1 .7 Luminaire Position and Orientation. Pole heig ht, a rm l ength, and pole offset from the road can sup plemental l ighting, the designer and governing authority shall decide whether lighting is warranted. all i nfluence a lighting calculation. Typical ly, each can be adjusted to optimize a desi g n . Once esta blished, 3.1 .9 Change in Physical Surroundings. The designer the l u m inaire is assig ned X, Y, Z coord inates descri bing should know as much as possi ble a bout future cha nges its position relative to the roadway. The orientation of that can affect road conditions. In the design process, the l u m i naire a lso needs to be defined. Luminaires are it is desirable to know when the pavement is in poor typical ly oriented at 0, 90, 1 80, or 270 degrees relative condition and whether it is likely to be resu rfaced early to the roadway. in the useful l ife of the lighting system. Consideration should a lso be g iven as to whether trees or border 3.1 .8 Impact of Vehicle Headlights. Hea d l ights a re the areas will be added, or whether nearby buildings will be primary system intended to assist drivers with seeing constructed or demolished. objects on and along the road. Veh icular head lig hts may provide adequate illumination on roadways where 3.1 .1 0 Impact of Trees on Lighting. Trees are an the d river has sufficient time for reaction and stopping important and valued element for the social, economic, on straight roads at speeds below 50 km/h (30 m i/h). a n d environmenta l benefits they provide a l l users. (Wet or icy pavements can extend the safe stopping However, if the size and shape of mature trees a re not d istance, and reaction time may be extended where taken i nto consideration as part of the l i g hting design, 3-7 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Figure 3-4a. Rendered image. Figure 3-4b. Extent of 1 -lux limit from headlight. Figure 3-4c. Extent of 2-lux limit from headlight. Figure 3-4d. Extent of 5-lux limit from headlight. (I mages courtesy of Paul Lutkevich, WSP) then roadway and roadside functions and safety can be a n i nvestigation conducted in Minnesota,8 trees were compromised. Tree location and species selection can found to have a significant i mpact on the l ig hting system reduce lighting levels below the thresholds intended a n d del ivered lighting levels. Light level measurements to mainta i n the safety of the roadway or the safety and were taken at two test locations i n the summer, when secu rity of pedestrians, bicyclists, and transit users, and l eaves were present on the trees, and in the winter, can prove to be a detriment to the intended functions when these deciduous trees had lost their leaves. In and safety of the roadway and roadside. Likewise, these tests, horizontal l ight levels on the sidewal ks were l ighting location and design that are incompatible with shown to be reduced 1 9% to 33%, and vertical lighting trees may req u ire excessive tree tri mm ing, which could va l ues were red uced 21% to 65% by the foliage. Figure prove to be unsusta inable in terms of maintenance 3-5 shows a n example of the different effects of trees and operations costs and detri mental to the intended with and without their foliage. function and hea lth of the trees. The effect of trees on lighting levels is not sufficiently It is i m portant that the presence of trees in pedestrian q u antified to develop exact modifications for desig ns, l ighting applications, such as streetscape i mprovement but this report s u g g ests a n anticipated additional projects, be carefu lly considered. These trees can have light l oss of 1 0% to 20% be included in design when a significant i m pact on the a mount of l ight delivered to new or existing trees a re i n c l ose proximity to the the target a reas, including the sidewa l k and roadway. In l ig hting. As a m i n i m u m, the l i g hting system should 3-8 Calculations be coord inated with any new or existing landscaping. Lig hting designers should also consider consu lting with arborists to evaluate the potential long-term i mpact of specific species of trees. 3.1 .1 0.1 General Considerations. • Both trees and roadway lighting are indispensable m u n icipa l assets. Thro u g h understa nd i ng a n d cooperation, those responsible for these assets can reduce conflict between trees and roadway l ighting. • Arborists should make tree selections based on those that will fit the ava i l a bl e roadway space with m i n i m u m conflict to uti l ities. Such selections m ig ht incl ude uprig ht, globu lar or ordinary tree shapes. I n many cases, proper pruning o f trees wil l reduce a ny obstruction of roadway lighting. • Low overhanging fol iage can seriously obstruct the light intended for the pavement and sidewalk, and excessive street overhang can impede truck or bus movement. J u d icious pru ning can reduce or eliminate the screening effect. (Refer to Section 9.2.7 for additional information on pruning.) 3.1 .1 0.2 Design Considerations. One of the objectives of the l ighting system design should be to m i n im ize conflicts with trees. This may be achieved throug h va riations in t h e lighting system layout with respect to l u m i naire spacing and mounting height, transverse pole location, and bracket length. Specific considerations incl ude: • Lighting desig ners should be actively involved in providing d i rection to the la ndscape designers to l i mit the size, type and future growth of decorative trees. Once the tree species have been decided, the trees should be modeled in l i g hting calculation software to ensure that what is del ivered to the target is accu rate, keeping i n mind the trees' future growth. • Lumi naires can be mou nted on l onger brackets or mast a rms. This generally increases construction costs to some extent, but the gain in l i g hting effectiveness Figure 3-5. Winter lighting conditions compared to those of summer, with respect to the influence of leaves. (I mage courtesy of Paul Lutkevich, WSP) may be substanti a l if foliage interference is red uced. • Align ment of l u m i na i res out over the street is i m porta nt with respect to both visi b i l ity and 3-9 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities appearance. The length of the l u m i naire su pport ind icate that, on average, the n u m ber of actua l conflicts should be selected to best meet the req u i rements between l u m i na i res and fol iage is approximately 50% of each particu lar street. Using longer supports on the more heavily wooded roadways. Of the total that approach the center of the street wi l l reduce existing roadway system, the fol iage interference is p r u n i ng considerab ly less than 50%. req u i rements but will increase the structural costs of the l i g hting system, and might be considered less aesthetica l ly appea l ing. This w i l l • also affect t h e distribution type o f t h e l u m inaire 3.2 Roadway Lighting Metrics - req u i red in the design. General I nformation The l u m i naire mounting height may be reduced, The following sections provide a basic overview of with a corresponding reduction in the spacing and roadway lighting metrics. The methodol ogy for each the use a l u m i naire of lower l u men output. This calculation type is found within its section. method materially i ncreases the cost of roadway l ighting due to more equ ipment being req u i red. • Conversely, where changes in the longitudinal spacing of l u m i na i res a re considered i n order to m i n imize conflicts with trees, changes i n the mounting height should also be considered. The variation in pavement i ll u m i na nce and l u minance should be checked in the design process. The overa l l design should b e reconsidered i f it resu lts in two o r more consecutive locations having spacing that varies more than 1 0% from the average spacing. • There may be some gain from u pward l ight that is reflected downward to the roadway and sidewal k by t h e foliage. Although the a mo u nt is small, this reflected light i ncreases the genera l adaptation level. • If the l u m inaire uses photocontrols, it is im portant to prune potentially i nterfering fol iage. This section introduces a new calculation a rea referred to as surround. Calculation of surrou nd is intended to a l low a d river to detect objects in the area adjacent to the travel lane. Figure 3-6(d) (see Section 3.2.3.1 .1 ) illustrates the su rround for a typical l u m i naire spacing. Criteria for application of su rround calcu lations a re given in Chapters 1 0 and 1 1 . Figure 3-6(d) a lso expa nds the explanations of the methodology for the roadway and street l i g hti ng ca l c u lations. Calculation a reas a re based upon the direction of travel. I n add ition, the term elemental area is introduced in the text. This is the a rea that is represented by the calculation point, as explai ned i n Section 3.2.3.1 .1 . W h i l e calcu lated i ll u m i na nce val ues can be rel iably compared to measu red va l ues, this is not the case for l u minance. While l u minance is calculated at a point, the measurement of l u m ina nce cannot be made at a point. Luminance measu rements are made based 3.1 .10.3 Design Data. The modern trend in roadway upon the intersection of the conical field of view of the l ighting practice is to use l ig ht sou rces of higher efficacy mea s u rement device with the horizontal plane. Because in l u m i na i res having light distributions appropriate for the angle of view is downward, this is a n e l l i ptical area. the l u m inaire spacing, m o u nting height, and transverse Thus, there is a difference between what is calculated positions, and for the roadway dimensions. Such proper (lum ina nce at a poi nt) and what can be measured with l ighting design is particula rly i mportant on residential a l u m i nance meter (lumi na nce of a n a rea). and l ocal streets. It should also be emphasized that in the circu mstances where we see by silhouette d iscernment It is not possible to prescribe calculation g rids for a l l (negative contrast), the h ig h-angle emission of l ig ht from situations, such as l eft-turn la nes, dedicating rig ht­ the l u m i naire is very i m portant. Obviously, with longer turn la nes, bike lane crossovers. When unique road spaci ng there are proportionately fewer l u m inaires, arrangements arise, eng ineering judg ment should be which in turn red uces the requirements for pru ning. This used to define calcu lation g rids. Sound eng ineering fu rther contributes to lower combined mai ntenance judgment rel ies on a n understanding of the l u m ina nce cost of trees and l ighting. Observations in d ifferent ca l cu lation method and its lim itations. Section 3.3 sizes of towns with properly desig ned roadway lighting provides additional i nformation in this regard. 3-1 0 Calcu lations Before the advent of com puters, roadway l i g hting ca l c u lations were completed by hand. S i n ce the • The pavement is level and the su rface homogeneous. • The pavement su rface is assumed to be d ry and advent of computers, computer capabilities and their to have directional light reflectance characteristics applications have g rown exponentia l ly. This has resu lted that a re expressed in terms of a reduced l u m inance in com puter-a ided design and ana lysis rep lacing the coefficient, r, as described in Section 3.3.1 . hand calculation method of roadway l i g hting. (See Chapter 8 - Computer Applications, for information on lighting calcu lation software and its applications in roadway lighting desi g n .) The ca l c u lation and measure ment g rid shall be in accordance with Figure 3-6 (Section 3 .2.3.1 .1 ). C a l c u lations and measure ments may be made at //luminance is the density of l u minous flux (light) incident on a su rface. It is measured using a lig ht-sensitive cel l . If the cell surface is horizontal, it is termed horizontal illuminance, whereas if the cell is vertical it is called vertical illuminance. add itional points, but designers should use only the g rid points for determining compliance with reco m mended averages, percentiles, maximu ms, and m i nimu ms. Only fixed-position l u m i naires insta l led for the pu rpose of providing roadway and pedestrian lighting are to be Pavement luminance is the l u m i nous intensity per unit projected area reflecting off the roadway surface toward an observer. In simpler terms, illuminance is the amount of light reaching a su rface, and luminance is the amount of light leaving a su rface. Object luminance is the l u minous intensity per unit projected area reflected off (or emitted from) the su rface of an object toward an observer. considered in the calculations. The light distribution of those l u m i naires is assumed to be represented by a table of l u m inous intensities, which provides specific va l ues of l u m inous intensity in appropriate directions relative to the l u m inaire so that l inear interpolation yields results that are accurate within five percent. 3.2.2 Accuracy of Calculations. The accuracy of calcula­ For this Recommended Practice, l u m i na nce is the selected design method for straight highways and streets, tions for pavement luminance and STV depends on: • (LLF) (see Section 3.1 .6) i nto a l l calcu lations horizontal and vertical illuminance are used for pedestrian areas, and horizontal illuminance is used for intersections, The incorporation of a n appropriate l ig ht loss factor • Whether o r not the photometric data used to determine the l u minous intensity at a particular interchanges, and curved sections of roads and streets, angle correctly represent the output of the lamp where luminance can be difficult to calculate. and l u m i naire For determining the horizontal i l l u minance level to be used i nstead of the recommended l u m ina nce level, • Whether or not the d i rectional reflectance table accu rately represents the reflectance of the su rface the fol lowing equ iva lencies may be used: 1 cd/m2 for 1 0 lux on Rl pavement; 1 cd/m2 for 1 5 lux on R2 or R3 3.2.3 Selection of a Grid and Luminaire Location pavement; and 1 cd/m2 for 1 3.3 lux on R4 pavement. Geometry for Calculations. Different procedu res are Field val idation of a lighting system's performance may req u i red when selecting a grid for straight roadway be done by measuring l uminance or i l l u m i nance. (Note: sections, cu rves, or traffic conflict a reas. While exact Recommended i ll u m i nance un iform ity ratios a re the rules can not be specified for all situations, the intent of same as those provided for l u m i na nce uniformity.) this discussion is to i l l u strate principles that should be followed in selecting grids and l u m inaire locations for 3 .2.1 Assumed and Standard Conditions. For calculations or measurements. calcu lations to determine whether a lighting insta l lation meets the reco m mendations found i n Chapters 10 and 3.2.3.1 Straight Roadway Areas. 1 1 , the fol l owing assumptions apply: the l u minaires and calculation poi nts to be used i n • Determi nation of The observer position and direction of view are t h e cal cu lation o f l u m inance, i ll u m i nance, and vei l i n g fixed (see Section 3.2.3.1 .2). l u m i nance is dependent u pon t h e geometry o f the 3-1 1 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities layout. The inclusion of lighting contribution at a point protocol as was used for the adjacent roadway lane: is l i mited by the a n g u l a r boundaries of the r-tables with there should be two calcu lation l ines per surround area. one exception as noted below. Only l u minaire-point The surround area length is bounded by the l u m i naire combinations that result in a non-zero r va l ue should cycle. The width of the surround shall be 3.6 m. be used in the cal c u lation of the average and the un iformity ratios. (See Section 3.3.5.) The fol lowing specifics pertaining to the calculation points are demonstrated in Figures 3-6(a) through 3-6(d): The exception is for vei ling l u m i na nce. L u m i na ires • Area and points are typical as shown: two transverse shall be added away from the g rid of poi nts u ntil points per lane at each longitudinal point along the l u m inaire-point combination yields a zero r value. one l u m i naire cycle. Long itudinal ly, calcu lation Luminaires shall be added toward the observer all the points shall be placed so that there are at least 1 0 way to the observer position, even if this exceeds the points along the road, not more than 5 meters on a n g u l a r bounds of the r-table, to properly calcu late center, in a l u minaire cycle. The starting point for vei l i ng l u m inance as seen by the observer. Luminaires i n the g rid lines shall not be located directly under the this ra nge should not b e used for l u m i nance calcu lations l u m i naire, but the g rid shall start at a point one-half if the l u minaire-point combination yields a zero r val ue. of the elemental-area size from the l u m i naire. Lateral (transverse) lines of calculations are one-quarter the 3.2.3. 7. 7 Determination of Calculation Point Locations for a Typical Luminaire Cycle. Calculation points to determine lane width from the edge of the travel lane. • Lumina nce calcu lations a re made for each d i rection compliance with criteria shall be placed within a l u minaire of travel. The observer moves with the poi nts cycle using the fol l owing protocol: each calculation point parallel to the roadway, keeping a fixed distance represents the lighting for an area, referred to as a n and d i rection of view (see Section 3.2.3.1 .2). elemental area (see Section 3.2 Roadway Lighting Metrics - General Information). The calcu lation point is • in the center of the elemental area. The grid of calculation • shall u se the same For veiling luminance calculations, the observer is at the same location as the luminance observer. The areas fil l the typical area within a l u minaire cycle without calculation shall include all luminaires used in the extending beyond the l imits of the l u minaire cycle a long luminance calculations, (provided the luminaire-point the road (longitudinally). combination results in a non-zero r va lue) as well as any luminaires added all the way to the observer position. Across the road, there shall be two calcu lation lines per la ne, and location of the points across the road sha l l be ca l c u lations luminance calcu lations. points shall be selected so that for straight roadway sections between traffic conflict areas, the elemental l l l u m i na n ce luminaire-point combi nations as wou ld be used i n • Su rround ratio sha l l be calcu lated based upon the spaced so that the elementary areas a re bounded by average i ll u m i na nce of the surround d ivided by the lanes of travel (see Figure 3-6). In the event that the the average i ll u m i na nce of the adjacent lane. For roadway varies in nu mber of la nes (e.g., left turn la nes the pu rpose of the calcu lation, the width of the added before i ntersections), the g rid sha l l be based on su rround shall be 3.6 m. Surround ratio is d iscussed the n u m ber of la nes for the majority of the length of further in Chapters 10 and 1 1 . the roadway. I n the event that the roadway width and num ber of lanes change, then a revised g rid shall be Luminaire location geometry refers t o the spacing, used for the new width of the roadway. mounting height, overhang, tilt, and orientation of the l u m inaire. Adjacent to the outer la nes of travel, a calculation a rea referred to as surround (see Section 3.2 Roadway Contributed values from a l u m i naire to a calcu lation Lighting Metrics - General Information) shall be point shal l be included in the l u mina nce calcu lations added when the application warrants. The calcu lation only when the l u m i naire-point combi nation has a n r points for the surround shal l be defined using the same va lue that is non-zero. 3-1 2 Calcu lations Figure 3-6(a). Luminaires on 1 side, travel in 1 direction. (Graphic cou rtesy of Ray Yeager) Figure 3-6(b). Luminaires on 1 side, travel in 2 directions. (Graphic courtesy of Ray Yeager) Figure 3-6(c). Luminaires on opposite sides, travel in 2 directions. (G ra phic cou rtesy of Ray Yeager) 3-1 3 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Figure 3-6(d). Luminaires staggered, travel in 2 directions. (Graphic courtesy of Ray Yeager) llluminance calculation points for intersections shall be for 3.2.3.2 Pedestrian Walkways. The calcu lation poi nts for the conflict area as defined in Chapter 12, Section 12.3.2. horizontal i ll u m i na nce in the pedestrian a rea within the For l u m i n a nce a n d the same d istance on center as the spacing along the street right of way shall be spaced along the sidewalk 3.2.3. 1.2 Location of Observer. vei l i n g l u m i n a n ce c a l c u lations on stra i g ht roads, roadway: at least 10 poi nts no more than 5 meters apa rt, the observer's eye height is 1 .45 meters a bove the starting at a point one-half of the g rid cel l size from the road, with a 1 -deg ree downward viewing a n g l e. This l u m i na i re. The calcu lation points shall be positioned in geometry then l ocates the observer 83.07 meters the center of the sidewa l k pedestrian a rea and located a head of each ca l c u l ation point. The observer moves at s idewa l k level (see Figure 3-7). para l lel to the edge of the roadway, keeping a constant geometrical relationship with each calcu lation poi nt Calculation points for vertical illuminance in the pedestrian the observer is looking at. area shall be 1 .5 m above the pavement. The reflectance Figure 3-7. Calculation grids for sidewalks within roadway right of way. A: Sidewalk horizontal illuminance grid point at sidewalk grade. 8: Roadway horizontal grid point. C: Sidewalk grid based upon pedestrian luminaire cycle. D: Sidewalk vertical illuminance at 1 .5 m above sidewalk (arrows Indicate direction of vertical calculations). E: Vertical illuminance calculation adjacent to the pole on the horizontal grid shall be omitted for sidewalk calculation (typical for both ends of luminaire cycle). (Graphic courtesy of Ray Yeager) 3-14 Calculations of the walkway surface should be incorporated into the veh icular traffic must merge, d iverge, or weave to reach calculation of vertical illuminance. A diffuse reflectance either a thro u g h traffic lane or an exit la ne. Where traffic value should be used. Orientation of the vertical calculation confl ict a reas do not involve merg i n g or d iverg i n g shall be in each direction parallel with the main pedestrian veh icle lanes, t h e normal g rid should continue without flow. For a typical luminaire cycle along a sidewalk, the first change, and a ny g rid point fa l l i n g within the defined and last vertical calculation point location may be omitted. traffic conflict a rea sho u ld meet the criteria for that (See Figure 3-7.) area as defined in this Recommended Practice. Where traffic conflict areas do i nvolve merging, divergi n g Where pedestrian lighting poles a re present in addition or weaving, there should be two g rids superimposed to roadway l ig hting, the calcu lation g rid for the sidewa l k on that a rea. Each grid sho u ld fol l ow the ru les for its s h o u l d b e spaced u s i n g t h e distance between the lanes prior to entering the traffic conflict area. The pedestrian lighting poles as the calculation cycle, as g rids can be separate or forced to coincide, depend ing shown i n Figure 3-7. on the desire of the designer and the capability of 3.2.3.3 Cu rved Roadway Sections. Cu rved roadway veh icle approaching the traffic conflict area should be sections (less than 600 -meters in radius) and roads with considered an observer and ca lculations made for the steep and variable g rades (6 percent or g reater) can appropriate g rid points that define the lane(s) that the be calcu lated with the horizontal i l l u m inance method, d river might use to enter the traffic conflict area. the calcu lation prog ram. In any event, the d river of a using a rectangular g rid spacing with a spacing of no more than 2 meters by 2 meters on the travel lanes, 3.2.3.5 Cul-de-Sac. surrou nd, and bike lanes. (See Figure 3-8.) The l ig ht horizontal i ll u m i na nce i n a cul-de-sac should include The calcu lation g rid for the levels can be derived using the i l l u m inance- l u minance the area beg inning at the end of the curb return and equ ivalencies g iven in Section 3.2 for the pavement conti n u i ng throug hout the cul-de-sac. The g rid spacing classification u nder consideration. should be no g reater than 2 meters. 3.2.3.4 Traffic Conflict Areas. Traffic conflict areas can 3.2.3.6 Mid block Crosswalk. The horizonta l i l l u m inance be d ivided into two types: areas where vehicles conflict calcu lation g rid for the m id block crosswa l k should be with crossing vehicles and pedestrians, and areas where centered in the crosswal k. Maxi m u m spacing of the Figure 3-8. Calculation grid for a typical section of a curved roadway (less than 600-meter radius). (Graphic courtesy of Ray Yeager) 3-15 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 3.2.3.7 Intersection. The calculation grid for the horizontal illuminance in an intersection depends upon the intersection layout. The grid spacing should be no greater than 2 meters on center. (Refer to Chapter 12 for additional information.) 3.3 Calculation of Roadway Pavement Luminance The luminance method of roadway lighting design approximates the "brightness" of the road as it may appear to the driver of a vehicle. The pavement luminance at a point is dependent on the illuminance at that point and the ---!-- APPROA.CH ROA.D pavement's reflectance in the direction of an observer. It is measured with a luminance meter by the method described in Annex A. The luminance calculation is valid for consistent luminaire spacing at a constant set back from the road. Figure 3-9. Calculation grid for a cul-de-sac. The calculation area is valid for multiple luminaire cycles (Graphic courtesy of Gregg Hyde) provided the conditions described in Section 3.2 and in this section are met. Generally, luminaire-point combinations calculation poi nts should be 0.5 m on center. The line of should be used that result in valid values on the applicable calculation points should extend 1 m onto the sidewalk. r-table (see Section 3.3.1 and Section 3.3.4). When the This a l l ows for at least two horizonta l calcu lation points spacing between roadway luminaires or the setback is to be on the sidewalk. inconsistent, the illuminance method should be used. be 1 .5 m Road surfaces do not reflect light diffusely but in a semi­ above the horizontal calculation points. The vertical specular manner; i.e., a portion of the light is reflected calculations sho u l d be oriented to face the oncoming specularly and a portion diffusely. The amount of light Vertica l -i l l u m ina nce calcu lations should vehicle travel . Figure 3-1 0 shows a n example of the calculation point locations. reflected in a given direction, e.g., toward an observer, varies depending on the angle of the incident light ray, as measured in both the vertical and horizontal planes (see Figure 3-1 1 in Section 3.3.3). As described in Section 3.2.3.1 .2, the relative position of each calculation point with respect to the observer is fixed. The observer is considered a "moving observer" because his position changes for each luminance point calculation. Because the observer's viewing angle is assumed fixed at one degree below horizontal, the light reflecting from the point at an angle of one degree above the pavement surface is considered. 3.3.1 The r-Tables. The d i rectiona l reflectance characteristics of a surface are a function of three angles, as shown in Figure 3-1 1 (Section 3.3.3). Since the normal line of a driver's vision is downward and at points some distance ahead of the vehicle, a viewing direction (a) of 1 degree downward has been selected. The data can Figure 3-10. Horizontal and vertical illuminance then be shown as an array. This Recommended Practice calculation grids for a midblock crosswalk. has adopted the angular nomenclature and format of (Graphic courtesy of Ray Yeager) the CIE, shown in Tables 3-2 through 3-5. The values i n 3-1 6 Calculations the r-tables represent the reduced l u minance coefficient and is defined as the solid-angle-weighted average of r." The r values are not pure reflectance but are the the l u minance coefficients for the relevant directions of l umina nce coefficient q at angles f3 and y mu ltiplied incident lig ht.9 Each r-table shows the applicable Q0 value. factor MF, which is often 1 0,000 so that they are larger, The 57 va lue describes the relative specularity of the by the cosine cubed of y and then multiplied by a integer numbers. The average l u minance coefficient Q0 road surface. A low 57 value represents a more diffuse ("Q-zero") represents the "lightness" of the pavement surface. A h i g h 57 value represents more specular su rface. 57 can be calcu lated from the r-tables: ** reduced lumina nce coefficient, r: The value at a point on the pavement defined by ang les beta and gamma which, when multiplied by the appropriate luminous intensity from a luminaire and divided by the square of the mounting height, will yield the R(/3 = 0, tan y = 2) R(/3 = 0, tan y = 0) ' SJ pavement lumina nce at that point produced by the luminaire. Table 3-2. r-Table for Standard Surface R1 ' r• nF.11U':.lllll o r. · -· " . -'" · :"' Angle P (degrees) Tan 0 2 5 10 15 20 25 30 35 40 45 60 75 90 1 05 1 20 1 35 1 50 165 1 80 0 655 655 655 655 655 655 655 655 655 655 655 655 655 655 655 655 655 655 655 655 0.25 619 619 619 619 610 61 0 61 0 610 610 610 61 0 61 0 61 0 601 601 601 601 601 601 601 0.5 539 539 539 539 539 539 521 521 521 521 521 503 503 503 503 503 503 503 503 503 0.75 431 431 431 431 431 43 1 431 431 431 431 395 386 371 371 371 371 371 386 395 395 v 1 .0 341 341 341 341 323 323 305 296 287 287 278 269 269 269 269 269 269 278 278 278 1 .25 269 269 269 260 251 242 224 207 1 98 1 89 1 89 1 80 1 80 1 80 1 80 1 80 1 89 1 98 207 224 1.5 224 224 224 215 1 98 1 80 171 1 62 1 53 148 1 44 144 139 139 139 144 148 1 53 1 62 1 80 1 .75 1 89 1 89 1 89 171 1 53 139 130 121 1 17 112 1 08 1 03 99 99 1 03 1 08 112 121 130 139 2.0 1 62 1 62 1 57 135 117 1 08 99 94 90 85 85 83 84 84 86 90 94 99 1 03 111 2.5 121 121 117 95 79 66 60 57 54 52 51 so 51 52 54 58 61 65 69 75 3.0 94 94 86 66 49 41 38 36 34 33 32 31 31 33 35 38 40 43 47 51 3.5 81 90 66 46 33 28 25 23 22 22 21 21 22 22 24 27 29 31 34 38 4.0 71 69 55 32 23 20 18 16 15 14 14 14 15 17 19 20 22 23 25 27 4.5 63 59 43 24 17 14 13 12 12 11 11 11 12 13 14 14 16 17 19 21 8.7 8.7 9.0 10 11 13 14 15 16 16 5.0 57 52 36 19 14 12 10 9.0 9.0 8.8 5.5 51 47 31 15 11 9.0 8.1 7.8 7.7 7.7 6.0 47 42 25 12 8.5 7.2 6.5 6.3 6.2 6.5 43 38 22 10 6.7 5.8 5.2 5.0 4.2 7.0 40 34 18 8.1 5.6 4.8 4.4 7.5 37 31 15 6.9 4.7 4.0 3.8 8.0 35 28 14 5.7 4.0 3.6 3.2 8.5 33 25 12 4.8 3.6 3.1 2.9 9.0 31 23 10 4.1 3.2 2.8 9.5 30 22 9.0 3.7 2.8 2.5 1 0.0 29 20 8.2 3.2 2.4 2.2 1 0.5 28 18 7.3 3.0 2.2 1 .9 1 1 .0 27 16 6.6 2.7 1 .9 1 .7 1 1 .5 26 15 6.1 2.4 1 .7 1 2.0 25 14 5.6 2.2 1 .6 Oo = 0.10; 51 = 0.25; 52 = 1 .53 3-1 7 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Table 3-3. r-Table for Standard Surface R2 Angle /J (degrees) Tan y 0 0 390 390 390 390 390 390 390 390 0.25 41 1 41 1 41 1 41 1 41 1 41 1 41 1 41 1 0.5 41 1 41 1 41 1 41 1 403 403 384 379 0.75 379 379 379 368 3S7 346 32S 303 1 .0 33S 33S 33S 32S 292 291 260 238 216 1 .25 303 303 292 271 238 206 1 84 1 S2 130 119 1 08 1 00 1 03 1 06 1 08 108 114 114 119 119 1.5 271 271 260 227 179 1 S2 141 119 1 08 93 80 76 76 80 84 87 89 91 93 9S 74 2 5 10 15 20 25 30 35 40 45 60 75 90 1 05 1 20 1 35 150 165 1 80 390 390 390 390 390 390 390 390 390 390 390 390 41 1 41 1 379 368 3S7 3S7 346 346 346 33S 33S 33S 370 346 32S 303 281 281 271 271 271 260 260 260 281 260 238 216 206 206 206 206 206 206 206 206 1 9S 1 73 1 S2 1 S2 1 S2 1 S2 1 S2 141 141 141 141 1 .75 249 238 227 1 9S 1 S2 12 106 91 78 67 61 S2 S4 S8 63 67 69 71 73 2.0 227 216 1 9S 1 S2 117 49S 80 67 61 S2 4S 40 41 4S 49 S2 S4 S6 S7 S8 2.5 1 9S 1 90 146 110 74 S8 48 40 3S 30 27 24 26 28 30 33 3S 38 40 41 3.0 1 60 lSS llS 67 43 33 26 21 18 17 16 16 17 17 18 21 22 24 26 27 3.5 1 46 131 87 41 2S 18 lS 13 12 11 11 11 11 11 12 14 lS 17 18 21 4.0 1 32 113 67 27 lS 12 10 9.4 8.7 8.2 7.9 7.6 7.9 8.7 9.6 11 12 13 lS 17 4.5 118 9S so 20 12 8.9 7.4 6.6 6.3 6.1 S.7 S.6 S.8 6.3 7.1 8.4 10 12 13 14 5.0 1 06 81 38 14 8.2 6.3 S.4 s.o 4.8 4.7 4.S 4.4 4.8 S.2 6.2 7.4 8.S 9.S 10 11 3.8 5.5 96 69 29 11 6.3 S.1 4.4 4.1 3.9 6.0 87 S8 22 8.0 s.o 3.9 3.S 3.4 3.2 6.5 78 so 17 6.1 3.8 3.1 2.8 2.7 7.0 71 43 14 4.9 3.1 2.S 2.3 2.2 7.5 67 38 12 4.1 2.6 2.1 1 .9 8.0 63 33 10 3.4 2.2 1 .8 1 .7 8.5 S8 28 8.7 2.9 1 .9 1 .6 1 .S 9.0 SS 2S 7.4 2.S 1 .7 1 .4 9.5 S2 23 6.S 2.2 1 .S 1 .3 1 0.0 49 21 S.6 1 .9 14. 1 .2 1 0.5 47 18 S.O 1 .7 1 .3 1 .2 1 1 .0 44 16 4.4 1 .6 1 .2 1 .1 1 1 .5 42 14 4.0 1 .S 1 .1 1 2.0 41 13 3.6 1 .4 1 .1 3-1 8 Q0 = 0.07; 51 = 0.58; 52 = 1 .80 Calculations Table 3-4. r-Table for Standard Surface R3 Angle /J (degrees) Tan 0 2 5 10 15 20 25 30 35 40 45 60 75 90 1 05 1 20 0 294 294 294 294 294 294 294 294 294 294 294 294 294 294 294 294 294 0.25 326 326 321 321 317 312 308 308 303 298 294 280 271 262 258 253 249 0.5 344 344 339 339 326 317 308 298 289 276 262 235 217 204 1 99 1 99 1 99 0.75 357 353 353 339 321 303 285 267 244 222 204 1 76 1 58 149 149 1 49 1 45 1 .0 362 362 352 326 276 29 226 204 181 1 58 140 118 1 04 1 00 1 00 100 y 1 35 150 165 1 80 294 294 294 244 240 240 1 99 1 94 1 94 136 136 140 100 100 1 00 1 00 1 .25 357 357 348 298 244 208 1 76 1 54 136 118 1 04 83 73 70 71 74 77 77 77 77 1.5 353 348 326 267 217 1 76 145 117 1 00 86 78 72 60 57 58 60 60 60 61 62 1 .75 339 35 303 231 1 72 1 27 1 04 89 79 70 62 51 45 44 45 46 45 45 46 47 2.0 326 321 280 1 90 136 1 00 82 71 62 54 48 39 34 34 34 35 36 36 37 38 2.5 289 280 222 1 27 86 65 54 44 38 34 25 23 22 23 24 24 24 24 24 25 3.0 253 235 1 63 85 53 38 31 25 23 20 18 15 15 14 15 15 16 16 17 17 3.5 217 1 94 122 60 35 25 22 19 16 15 13 9.9 9.0 9.0 9.9 11 11 12 12 13 4.0 1 90 1 63 90 43 26 20 16 14 12 9.9 9.0 7.4 7.0 7.1 7.5 8.3 8.7 9.0 9.0 9.9 4.5 1 63 1 36 73 31 20 15 12 9.9 9.0 8.3 7.7 5.4 4.8 4.9 5.4 6.1 7.0 7.7 8.3 8.5 5.0 145 1 09 60 24 16 12 9.0 8.2 7.7 6.8 6.1 4.3 3.2 3.3 3.7 4.3 5.2 6.5 6.9 7.1 5.7 5.5 1 27 94 47 18 14 9.9 7.7 6.9 6.1 6.0 113 77 36 15 11 9.0 8.0 6.5 5.1 6.5 1 04 68 30 11 8.3 6.4 5.1 4.3 7.0 95 60 24 8.5 6.4 5.1 4.3 3.4 7.5 87 53 21 7.1 5.3 4.4 3.6 8_ 4 .4 7 � 1_ 3._ 8_ .1�__ 6 _ 3�_47 6_ 3 .1 .0 _ _ _ _ _ _ � _ _ _--+--t---+---t ,_ 8 .5 78 42 15 5.2 3.7 3.1 2.6 9.0 73 38 12 4.3 3.2 2.4 9.5 69 34 9.9 3.8 3.5 2.2 1 0.0 65 32 9.0 3.3 2.4 2.0 1 0.5 62 29 8.0 3.0 2.1 1 .9 1 1 .0 59 26 7.1 2.6 1 .9 1 .8 1 1 .5 56 24 6.3 2.4 1 .8 1 2.0 53 22 5.6 2.1 1 .8 <>o = 0.01; 51 = 1 .1 1 ; 52 = 2.38 3-19 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Table 3-5. r-Table for Standard Surface R4 Angle /J (degrees) Tan y O 2 5 10 15 20 25 30 35 40 45 0 264 264 0.25 297 317 264 264 264 264 264 264 264 264 317 317 317 31 0 304 290 284 277 0.5 330 0.75 376 343 343 343 330 310 297 284 277 383 370 3SO 330 304 277 2S1 231 1 .0 396 396 396 330 290 2S1 218 1 98 1 8S 1 6S 1 .25 403 409 370 310 2S1 211 1 78 1 S2 1 32 1 .5 409 396 3S6 284 218 1 72 139 11S 1 00 60 75 90 1 05 1 20 1 35 264 264 264 271 244 231 264 2S1 218 1 98 1 8S 1 78 1 72 1 72 211 1 98 1 6S 139 1 32 1 32 12S 12S 14S 112 86 86 86 86 86 11S 1 03 77 66 6S 6S 63 88 79 61 so so so so 150 165 1 80 264 264 264 264 264 264 264 224 224 21 8 218 211 211 211 1 6S 1 6S 1 6S 12S 119 119 87 87 87 6S 66 67 68 S2 SS SS SS 1 .75 409 396 343 2S1 1 78 139 1 08 88 7S 66 S9 44 37 37 37 38 40 41 42 4S 2.0 409 383 317 224 14S 1 06 86 71 S9 S3 4S 33 29 29 29 30 32 33 34 37 2.5 396 3S6 264 1 S2 1 00 73 SS 4S 37 32 28 21 20 20 20 21 22 24 2S 26 3.0 370 304 211 9S 63 44 30 2S 21 17 16 13 12 12 13 13 1S 16 17 19 3.5 343 271 1 6S 63 40 26 19 1S 13 12 11 9.8 9.1 8.8 8.8 9.4 11 12 13 1S 4.0 317 238 1 32 4S 24 16 13 11 9.6 9.0 8.4 7.S 7.4 7.4 7.S 7.9 8.6 9.4 11 12 4.5 297 211 1 06 33 17 11 9.2 7.9 7.3 6.6 6.3 6.1 6.1 6.2 6.S 6.7 7.1 7.7 8.7 9.6 5.0 277 1 8S 79 24 13 8.3 7.0 6.3 S.7 S.1 s.o s.o S.1 S.4 s.s S.8 6.1 6.3 6.9 7.7 5.5 2S7 1 61 S9 19 9.9 7.1 S.7 s.o 4.6 4.2 6.0 244 140 46 13 7.7 S.7 4.8 4.1 3.8 6.5 231 1 22 37 11 S.9 4.6 3.7 3.2 7.0 218 1 06 32 9.0 s.o 3.8 3.2 2.6 7.5 20S 94 26 7.S 4.4 3.3 2.8 8.0 1 93 82 22 6.3 3.7 3.9 2.4 8.5 1 84 74 19 S.3 3.2 2.S 2.1 9.0 1 74 66 16 4.6 2.8 2.1 9.5 1 69 S9 13 4.1 2.S 2.0 1 0.0 1 64 S3 12 3.7 2.2 1 .7 1 0.5 1 S8 49 11 3.3 2.1 1 .7 1 1 .0 1 S3 4S 9.S 3.0 2.0 1 .7 1 1 .5 149 41 8.4 2.6 1 .7 1 2.0 14S 37 7.7 2.S 1 .7 3-20 q, = 0.08; 51 = 1 .55; 52 = 3.03 Calculations 3.3.2 Pavement Classification Systems. I When many pavement sam ples are photometered and the d i rectional l u minous intensity (cd) at angles gamma and phi r reflectance characteristics a n a lyzed, it becomes apparent that natura l groupings occur, and red uced coefficient of reflectance at MF = it is possi ble to represent a g roup of typical pavements by a single r-table. Since the color of agg regates and H bi nders can change with little resulting difference in d i rectional characteristics, accuracy can be i ncreased if = LLF= the Oo is expressed separately. A ratio of the sta ndard f3 Oo and the specific Oo of a particular pavement can then be used i n the calcu lations to adjust for a specific angles gamma and beta multiplying factor used by the r-table (often 1 0,000) l u m inaire mounting height above the pavement surface (meters) light loss factors angle of deviation y vertical photometric angle (taken in a angle of observation pavement. l u m inaire's i nstalled position) horizontal photometric angle 3.3.3 Formulas and Units. Angles relating to the calcu lation of pavement l u minance and l ight emission from the l u m inaire a re shown in Figure 3-1 1 . Pavement l u m i n a nce i s ca l c u lated i n candelas per square meter (cd/m2) using: L = l(rfJ, y) x r (/3, y) x LLF MF x H of the va l ues calculated for all contri buting l uminaires. Lu minaires contributing to point P include all l u m inaire­ point combi nations that have a non-zero r va l ue. Determination of valid l u minaire-point combinations is illustrated i n Section 3.3.5. 3.3.4 Summary of Pavement Luminance Data. Pavement luminance data is summarized in terms of the where: L The total horizontal l u minance at point P is the sum pavement luminance from one individ u a l l u m i na i re a t point P average of the pavement luminance for all g rid points calculated. Uniformity ratios are calculated as fol lows: the average-to-minimum ratio is determined by dividing the average luminance at all grid points by the lowest grid point value; the maximum-to-minimum ratio is determined by dividing the highest luminance value at any grid point by the lowest luminance value at any grid point. 3.3.5 Example of Determining Valid Luminaire­ Point Combinations. Val id l u minaire-calcu lation point com bi nations to use in the l u minance calcu lations are determined by two factors (see Figure 3-12): • The horizontal distance on the g round plane from beneath the l u m inaire to the calcu lation point, divided by the mounting height a bove the ground plane (tan y) • The horizontal a n g le between the observer l i ne of sight and the vector from point P away from the luminaire, projected onto the g round p lane ((3) Orientation for illumi n ance a n d l u minance calculations. Va l i d l u minaire-point combinations are those that have Figure 3-1 1 . Geometric relationships for illuminance and va l ues on the r-table to be used in the calcu lations. An luminance calculations. exa mple is shown in Figure 3-1 3. 3-21 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities MH: Height of luminaire above ground plane �: Angle between observer line of sight and vector drawn away from calculation point from lumi naire. D: Horizontal distance along ground lane beneath the luminaire to the calculation point. Figure 3-1 2. Geometry for one luminaire-observer-calculation point combination. 3-22 Calculations ·-�·1 1·• • &."'ir.hr•tt:•'•..., 1.. r;........ .. ... ,... 0 ., 0.25 ...... . ,... ..)... .a '5 '° 0 2 5 10 15 20 JO JS 6S5 655 655 655 655 I 25 655 655 655 655 655 619 619 619 61.9 610 610 610 610 610 610 655 7S 90 655 655 655 610 610 610 539 539 5l9 Sl9 539 521 521 521 521 521 503 503 0.75 431 431 431 431 431 431 431 431 431 431 395 386 371 1.0 341 341 341 341 323 ; 323 305 296 287 287 278 269 269 05 S39 371 269 269 269 260 251 242 224 207 198 189 189 180 180 224 224 224 215 198 180 171 162 153 148 144 144 139 1.75 189 189 171 153 139 117 112 108 103 162 162 157 135 117 108 85 117 95 79 51 52 3.0 94 94 86 49 41 33 32 31 31 33 81 90 66 66 66 85 51 83 121 46 33 28 .90 54 34 99 121 94 99 25 130 99 U1 2.0 189 22 22 22 71 69 SS 32 23 20 21 22 4.0 21 45 63 59 43 24 14 11 11 13 8..7 u i s .o 17 8.7 9.0 10 35 60 57 38 25 18 23 13 36 16 52 15 14 u u 11 57 52 36 19 14 12 10 9.0 9.0 8.8 I 55 51 47 31 15 11 9.0 8.1 7.8 7.7 7.7 6.0 47 42 25 12 8.5 6.2 6.5 43 38 22 10 6.7 I 7.0 4'l 34 18 8.1 37 31 15 6.9 1.0 3S 33 I 75 15 I 7..2 6.5 6.3 5.8 S.2 S.6 4.8 u s.o 4.7 4.0 3.8 28 14 5.7 4.0 I 3.6 3.2 25 12 4.8 3.6 3.1 2.9 9.0 31 23 10 4.1 3.2 2.8 I 95 30 22 9.0 3.7 2.8 2_5 29 28 20 8.2 3.2 18 7.3 3.0 2.4 I 27 16 6.6 11.5 26 15 6_1 12.0 25 14 5.6 10.0 10.5 1: 11.0· 4.2 14 I 50 14 1S I 371 I 269 !I 269 180 180 11 180 139 ,11 139 11 144 1.25 84 371 269 15 I 105 I 120 i 655 11 655 601 601 I 601 : 500 503 SQ3 II 84 17 I 108 I 86 II 90 103 54 I 58 II 38 I 27 19 II 20 14 11 14 11 1 1 II 13 I 35 24 135 150 1&5 110 655 655 655 655 601 601 601 601 503 503 503 500 371 386 395 395 269 278 278 278 189 198 207 224 148 153 162 180 112 121 130 13.9 94 99 103 111 61 65 69 75 4'l 29 43 47 Sl 31 38 22 23 16 17 34 25 19 2:1 14 15 16 16 . 27 r values in this region are not valid 2..2 2.2 1-9 2..7 L9 L7 2.4 1.7 2.2 1-6 Figure 3-13. An example, for standard surface Rl, of the region of valid non-zero r values that may be used in luminance calculations. The non-zero r values are those in the red region; they are valid for use in the luminance calculation. The r values for fl and tan y in the blue area are not valid. In addition, values of tan y greater than 1 2 are not valid. 3-23 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities For illustrative purposes, the valid l u minaire-point combinations and the corresponding non-zero r-table Table 3-6. Example of Valid and Non-valid r Values for the Luminaires and Calculation Grid in Fig. 3-14 values are determined for the single point in lane 4, row 2 in Figure 3-14. The non-valid l uminaire-point combinations Delta X Distance Tan (meters) (meters) (meters) y G 1 52.5 1 2 .775 1 53.03 1 5.3 5 NO F 1 02.5 1 2 .775 1 03.29 1 0.3 7 YES E 52.5 1 2.775 54.03 5.4 14 YES are also determined. The units of the example are in meters. Mounting height is 10 meters. Luminaires are placed above the first row of calculation points in lane 1 . Luminaires are spaced 50 meters along the road. An example is one calcu lation point in lane 4, second row. Table 3-6 i l l ustrates the va lid, non-zero r val ues and the non-valid values, where there are no a pplicable r val ues. r Delta Y Luminaire p Value Valid? D 2.5 1 2.775 1 3 .02 1 .3 79 YES c -47.5 1 2.775 49.19 4.9 1 65 YES B -97.5 1 2.775 98.33 9.8 173 NO* A -1 47.5 1 2 .775 148.05 14.8 1 75 NO * Exception: Accepta ble to use in calculation of the veiling Figure 3-1 5 i l l ustrates the l ocations of the valid l u m ina nce at the observer. l u m i na i re-point combi nations for the l u m in a i res in Figure 3-14 and the appropriate non-zero r val ues. Also not va lid for the l u minance calculation and should be shown a re the l u m i naire-point combinations that are om itted from it. Figure 3-14. An example of a calculation grid, the luminaires (C, 0, E, F) that contribute to it, and three (A, B, G) that do not. Table 3-6 shows the r values that determine suitability of the luminaires. 3-24 Calculations ;I'1r.liio Tan v 0 0.2S 0.5 0.75 1.0 1.15 LS 1.75 2:. 2:.5 3.0 1.5 4.0 4.5 5.0 S.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9..5 ' l 619 i9 610 £10 I '6.!>5 S.39 S.39 539 539 539, 53'9 521 I u II 655 6 o I lC 43:1 43 1 431 431 431 43:1 43:1 431 0 2 s 10 1S 20 '6.55 6.S.:S. 655 655 655 £.55 l 25 ,510 ia 655 521 3:41 3:41 341 341 323 269 299 269 260 251 224 224 224 215 198 180 189 189 I 189 171 153 139 J 2 121 15 2:0 I 18 lV � 1� n ·� I 1n 6:9 55 32 59 43 24 57 52 36 51 47 31 47 42 25 12 &.5 7.2 43: 38 22 10 6..7 5.8 3:4 18 8.1 5_,5 4.8 3:7 31 15 6.9 4_7 4.0 35 28 4 5.7 4"0 3.6 3:3: 25 12 4 ..8 3-£ 31 23 10 4.1 3.2 2.8 llO.O 29 20 8.2 3.2 2.. 2.2 i0.5 11.0 i1.5 _:12.0 28 18 27 1£ L9 1.7 40 26 15 2S. 14 7. YN . " ..r. L. 6 6. 1 5.. 6 � 17 2.4 L7 2. 2._ i_,s 4 ,00 .1 u 2. I '6.5 S..2 IU I 189 12 23 71 ,53 II 198 I 38 46 287 22 28 66 66 431 521 23 41 33 94 90 86 81 79, 655 25 49 95 J .as 85 130 £6 11? u 207 ..., I 153 121 11 n? I 90 57 I 54 I g l 121 94 224 I 171 u 162 36 148. 112 52 II 34 33 I 22 16 I 15 9.0 I 9.() 7�7 6.3 5.0 4.2 14 II 12 I 6.2 I ...,ll• t;[ii];,;m � 655 ru.o II 521 I 431 323 I � 296 I 287 242 ;i11'r Anlt• IJ 11 u 7_7 ,_,,, I '° II SSS o I 6 10 II sro, 395 I � 278 I 269 189, II 180 52 1 I 14'1 108 1 100, s I 83 Si I s.o 32 II 31 21 I 21 14 I 14 11 I 11 8.7 I 8 . 7 144 15 90 105 ua 135 150 165 180 655 '6.55 655 655 655 655 '6.S.5 l' '.50l ,001 503 503 500 1 S.03 503 S.03: 655 601 sen 37i 3:71 371 371 371 386 26:9 269 269 269 278 180 180 i89' 198 139 144 1A8 153 103 108 i12 121 I -- ,so � A1·9 99 'a 51 31 \4 l2 l1 35 9.. 0 10 2 13 ·1 395 I 278 207 I 162 14 \11 395 278 224 180 no i39 ,sg 75 111 58 61 65 38 40 29 43 47 Si 27 31 3:4 38 20 22 23 25 14 16 17 13 14 15 \ D: 1 .3, 79 VALID C: 4.9, 1 65 VALI I � 27 'I �16...1 21 16 Qo: 0.10; Sl : 0.25; S2 : 1.53 I 3:. 2 .9 ! F: 1 0.3, 7 VALID I I I 54 i2 15 l 99, i\ 24 19' J \ 22 E: 5.4, 1 4 VALID II Oi 8: 9.8, 1 73 VALID 38Z � A: 1 4.8, 1 75 NOT VALID G: 1 5.3, 5 NOT VALID Figure 3-1 5. An illustration of why r values shown in Table 3-6 are valid or non-valid. 3.4 Calculation of Roadway light ray stri kes the su rface. l l l u m inance calculations Pavement l l l u minance can be performed i n any plane. The plane in which the The i l l u m i nance method of roadway l ig hting design calculations a re to be underta ken will vary depending determines the a mount of light incident on the roadway on the a p p lication a n d is defined in the relevant su rface or on vertical su rfaces from the roadway lighting application cha pters in Part 2 - Design. system . The l ight seen by a d river is the portion that reflects from the pavement toward the d river, and because different pavements exhibit varied reflecta nce characteristics, a d ifferent i l l u minance level is needed for each type of standard roadway su rface. l l l u mina nce is easi ly calculated and measu rable and is not observer or pavement dependent. The i l l u m ina nce at a point on a roadway su rface w i l l be Photometric test reports for roadway luminaires typically include a n iso-i l l u m i nance diagram. This is essentia lly a contour representation of the i nitia l lux (or footca ndle) va l ues on a horizontal su rface for a single l u m i naire at a g iven mounting heig ht. The iso-i l l u m i nance diagra m c a n b e used t o conveniently find t h e initial i l l u m ina nce at a ny point along the iso-i l l u minance l ines. A conversion the sum of the i l l u m i nances generated by each l ig ht table is typically provided to aid in calcu lating for sou rce. These i l l u minance val ues a re dependent on d ifferent mounting heights. The factors are derived the l u m i nous intensity of the l u minaire in the direction using the inverse-sq uare law, where the i l l u m inance at toward the point, the distance of the l u m i naire from a point is inversely proportional to the square of the the point, and the angle of incidence at which the d istance. 3-25 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 3.4.1 Formulas and Units. Ang les relating to the U ni form ity may be expressed as the ratio of the calculation of i ll u m i na nce and light emission from the average level (of either i l l u m i na nce or l u minance) to the l u m i na i re are shown in Figure 3-1 1 (Section 3.3.3). m i n i m u m level. An a lternative specification may be the maximu m-to-m i n i m u m ratio. The average-to-m i n i m u m When the distances are i n meters, the i ll u m i na nce is in ratio is traditionally used for roadway l i g hting, while l ux. the max i m u m -to- m i n i m u m ratio is used for vei l i n g l u m i nance a n d STV criteria. l(r/J, y) x (COSy) 3 x LLF Hz Specified average-to-m inimum un iform ity ratios vary from 3:1 to 1 0:1 , depending on the roadway or street classification, the pedestrian conflict category, and the where: E,, horizontal i l l u m i nance from one i ndivid ual I l u m i naire l u m inous intensity at angles r a nd <P H l u m i naire mounting height a bove the pavement su rface (meters) LLF= l ig ht l oss factors r vertical photometric angle (taken in design metric (e.g., illu minance, l u m i nance). Recent visi bil ity research1 0 has suggested that a high l evel of visibil ity does not necessarily req u i re h i g h u n i form ity. I t h a s been suggested that seeing a n object, such as a pedestrian, may be enha nced if this object is silhouetted agai nst a background of varying l u m i na nce. l u minaire's i nsta l l ed position) horizontal photometric angle The total horizontal i ll u m i na nce or l u m inance at point 3.6 Two Metrics of G lare in Roadway Lighting 3.6.1 Veiling Luminance. I n street and h ighway P is the sum of the val ues calcu lated for a l l contributing l i g hting, veiling l u m i na nce, Lw is the metric used to l u m i naires. evaluate disability g l a re as experienced by the d river. Stray l ight within the eye, produced by l ight sources 3 .4.2 Sum mary of Pavement lllu minance Data. in the field of view, effectively superimposes a "ve i l " of Pavement i ll u m i na nce data are summarized in terms l u m i nance on the reti na. This decreases the apparent of the average of the pavement i ll u m i na nce at a l l g rid contrast of objects agai nst their background and can points. Uniformity ratios are calcu lated: the average-to­ sometimes cause visual d iscomfort. I n Table 1 0-1 m i n i m u m ratio is determined by d ivid ing the average and Table 1 1 -1 (in Chapters 10 and 1 1 , respectively), i l l u m i nance for a l l g rid points by the value for the lowest the criterion for l i miting g lare is expressed as the g rid point. vei l i n g l u m inance ratio, which is the vei ling l u m ina nce maxi m u m d ivided by the average l u m ina nce of the road su rface. In this way, l u m inaire "brightness" is considered 3.5 U n iformity Ratios A high degree of u niformity of roadway lighting has traditional ly been accepted as desirable. When a person looks into an a rea with hig her or lower l ig ht levels, the res u lting physiological adjustments a re col lectively in the context of the "brightness" of the road surface as seen by the d river. Ang u l a r re lationships between the l u m i n a i re, the observer, and the calcu lation point are as shown in Figure 3-1 1 , Section 3.3.3. I n this docu ment, the vei l i n g cal led adaptation. The presence of some bright a reas in l u m i nance associated w i t h point P is calculated for the the field of view can result i n insufficient sensitivity for observer located at 83.07 meters from point P. The viewing in the a reas of med i u m and lower l ight levels. observer is located as explained in Section 3.3.3 and is E l i m i nation of areas of excessively h i g h light levels looking at point P (see Figure 3 -1 6). Un its are related in eliminates the need for the eye to adapt to those high the same manner as in Sections 3.3 and 3.4. levels. 3-26 Calcu lations vei ling l u m i na nce can be m ultiplied by a factor to account for normal physiological cha nges in the eye due to i ncreased age. This factor is referred to as the aging factor (AF) 1 1 : T h e effect o f incorporating t h i s factor is t o increase the va lue of the calcu lated veiling l u m i nance. Table 3-6 shows the age and the corresponding age factor. I Table 3-6. Age Factors Age 25 35 45 55 Figure 3-16. Geometric relationships for calculating 65 veiling luminance. The downward (red line) viewing 75 direction is 1° (shown as a in Figure 3-1 1). 85 I I I I Age Factor 1 .0 1 .1 1 .2 1 .4 1 .7 2.3 3.2 3.6.2 Threshold Increment (Tl). Threshold i ncrement (Tl) is a n alternative method of expressing and l i miting where: Lv veiling l u m i nance from one i ndivid u a l l u minaire K 1 0 x (the vertical i l l u minance in lux at the plane of the observer's eye, which is perpendicular to the line of sight and adjusted for the effects of aging on vision). The observer i n this formula is assumed to have the visual performance of a 25-year-old. (See Section 3.6.1 .1 for calculation of age correction factors.) n e 2.3 - 0.7 log 1 0 (B) for e < 2; n = 2 for e ;:: 2 angle in degrees disability glare. It is used chiefly with the CIE form of roadway lighting calcu lations. When the contrast of an object to its background is said to be at threshold, the detection probability is 50%. If a g lare source is then introduced, visibility will fall below threshold. To return to the threshold, or 50% probability condition, contrast has to be increased. The amount of the contrast increase is a measure of the level of disability glare. Threshold increment is this contrast increase expressed as a percentage of the zero-glare threshold contrast. Put another way, it represents how much brighter, in percent, an object has to be in order to be seen in the same The veiling l u m inance (LJ due to a l l l ight sou rces is the conditions with a glare source present as compared to sum of the veiling l u mina nce of a l l of the i ndividual one without a glare source present. There is a relationship contributing sou rces. between threshold increment and veiling luminance12: 3.6.1 .1 Effect of Age on Veiling Luminance. Scatter of light i ncreases in the eye d u e to age related changes. TI = ( 60. 275 LJL 0 862 ) , These changes include yellowing of the cornea and lens Tl is not typical ly used in North American lighting as wel l as an increase in the given described in Section practice. H owever, it has been shown to correlate wel l 3.6.1 is based on a 25-year-old observer. The calculated with the veil i ng l u mina nce ratio. 3-27 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 3.7 Small Target Visibil ity (STV) 3.7.1 The roadway lighting metric Small Target Visibility (STV) relationships between the luminaire, the surface of a Calculating Target Luminance. is based on the visibility levels of an array of small targets vertical target and the observer are shown in Figure 3-18. Angular on the roadway and considers the following factors: The lum inance of the targets Units are related in the same manner as in Sections 3.3 • The l u minance of the i m med iate background and 3.4. The reflectance of the target su rface is assumed • The adaptation level of the adjacent surroundings • The presence of any d isability glare • to be La m bertian. LI = !(¢, r) x cos 2y x sin y x [Cos(90 ¢)] x 0.5 x LLF [H (0.5 x TH)] 2 x 1t - - The STV value is a weig hted average of the visibility level of these targets. This method m ight be a valuable where: tool when comparing the expected resu lts of two L, l u m inance of target due to one individual l u minaire d esigns del ivering approximately the same l u m ina nce I l u m inous intensity at angles r a nd rfJ H l u m inaire mounting height above the designs, but when comparing the STV values, the higher LLF= com bi ned l ight loss factors STV value (right-hand image) a lso seems to indicate 0.5 better target visibil ity for rows of targets on the roadway. TH = and illuminance performance. pavement surface (meters) Figure 3-1 7 shows two relatively similar l u minance = reflectance factor (diffuse) target height (typica l ly 1 8 cm) 3.7.2 Calculating Target Visibility. Small Ta rget Visibility (STV) is a weighted average of the val ues of target Visibil ity Level (VL) over a grid of poi nts on an area of roadway for one d i rection of traffic flow. Visibility Level is the amount above the visibility threshold that an object is to an observer. Visibility Level is a ratio and has no units. The target is located at grid Figure 3-17. Target visibility with similar pavement Figure 3-18. Geometric relationships for target luminance designs. (I mages courtesy of Ja mes Havard) lum inance calculations. 3-28 Calculations point P and is viewed by an observer located as per The third step is to calcu late a n u m ber of intermed iate Figure 3-1 6. The observer is assumed to be 60 years old, fu n ctions using the fol lowing equations: with normal eyesight and a fixation time of 0.2 seconds. log 1 0A + 0.523 The target is a flat su rface, 18 cm x 18 cm, standing B perpendicular to the road su rface. The target reflects C AA LL a + 6 AL 0.355 - {0.1217 [C2/(C2 - 1 0.40 C + 52.28)]} [(AA2 + A U) 1 12]/2.1 2.6 [(F1 12/A) + v12] 2 light in a Lam bertian ma nner with a reflectance of 50%. Target lum inance L, is calcu lated per Section 3.7.1 AZ for one point at the center of the target. Background DL1 = 0.36 + [(0.0972 82)/(82 - 2.513 B + 2.789)] l u m i nance Lb is the average of the pavement l u minance as viewed by the observer at a point adjacent to the The fourth step is to calculate Mbyone of three equations, center of the top of the target and at a point adjacent depend ing on the value of LL,,, and determine the value to the center of the bottom of the target. Pavement of a negative-contrast adjustment factor FCP. It is luminance of these two poi nts is calculated per Section i mportant to note that the calcu lation of FCP is not 3.3. Veiling l u m ina nce Lv is calcu lated for the observer accurate when LLa is less than -2.4 (La, the adaptation per Section 3.6.1 . l u m i nance, is less than 0.0041 8 cd/m2). In practice, such l ow levels of adaptation are never encou ntered with The val ues L,, Lb, and Lv are then used, together with negative contrast. constants for the target size, observer age and fixation ti me, to calcu late Visibil ity Level, VL. The first step is the determi nation of the adaptation l u m i nance (L.), the log of La (LLa), and the visual angle A If -2.4 < LLa < -1 ' then M = 1 o-{0.075 [(LLa + l)A2] + 0.0245 If LLa :<'. -1 ' then M = 1 o-{0.1 25 [(Lla + l)A2] + 0.0245 If LLa :'> -2.4 , then FCP = 0.5, and TGB and FCP [see next step] need not be calculated. in min utes subtended by the target. Then: La = Lb+ Lv LLa = log IO(La) A tan -1(Target size/Distance, observer to target) x 60 TGB = -0.6 L;o.1488 = And: Note: For the standard target size of 0.1 8 m on a side and a d istance from observer to target of 83.07 m, A is 7.45 FCP = 1 - [M (ATGB)/2.4 DLi] minutes. The fifth step is to adjust DL in accordance with the time The second step is the determi nation of the sensitivity of of observation T, which for this d ocu ment is a constant the visual system as a function of adaptation l u minance. 0.2 seconds. This is done by using one of three eq uations, depending on the va lue of La: DL2 = DL 1 [(AZ + T)!T] If La :<'. 0.6, The sixth step is to calcu late the adjustment (FA) for the then F = [log1 0(4.2841 La0·1 556) + (0.1684 La05867)] 2 and L = (0.05946 La0.466) 2 age of the observer (TA) and then adjust DL accord i ngly. If 0.0041 8 < La < 0.6, If observer age TA :'> 64, then FA = [(TA - 1 9)2/21 60] + 0.99 then F = 1 Ol2 l(0.0866 LLaA2) + (0.3372 LLa) - o.072]) and L = 1 012 (0 3 1 9 LLa - 1 256)] lfobserver age TA > 64, then FA = [(TA - 56.5)2/1 1 6.3] + 1 .43 If La < 0.00418, Then, . . the n F = 1 0 (0.346 LLa + 0.056) and L = 1 O l(0.0454 LLaA2) + (1.055 LLa) - 1.782] 3-29 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities The seventh step is to calculate the adjustment if the is a function of both direct and reflected l ight, the target is da rker than the background (negative contrast). reflectances of nearby surfaces should be considered in the calcu lation. This can be especially true for lig hter If L, < Lb, then DL4 = DL3 x FCP Otherwise, DL4 = DL3 colored surfaces such as sidewal ks. The calcu lation of vertical illuminance is similar to that for horizontal (see Section 3.4), except that the plane of calculation is The eighth and final step is to calculate VL. vertical. The i nverse-square law is used to calculate and then sum the direct component from each l u minaire. As shown in Figure 3-1 9, the direct component of vertical i l l u m inance at a point p (reflected l ight not considered) 3.7.3 Summary of Data. Small Ta rget Visibility val ues is calculated from: are typica l ly both positive and negative over an area on the roadway. An absol ute value of 1 .0 or less ind icates Ev = I cosf3/D 2 , that the target is below threshold for a standard observer who is a l l owed a fixation of 0.2 seconds. Large VL va l ues where: are not cou nted as heavily in the com putation of the Ev I i l l u m ina nce in a vertical p lane l u m inous intensity (cd/m 2) in the d i rection /3 the angle between the normal to the weig hted average, STV, in order to compensate for this saturation i n recog nition times. The computation of these summary values is as follows: 1 . Positive and negative va l ues of VL are made RWVL = 1 0 [-o su rface at p and the l u m i na i re (the complement of angle e) positive and converted to RWVL (Roadway Visibi l ity Level) va l ues: of p D the distance from the luminaire to p I I VLI] 2. The RWVL values are averaged to obtai n AWRVL: AWRVL = (Su m of all RWVL)/(Number of poi nts in the grid) 3. The ARWVL average is converted to weighted average VL, or STV, by the equation: STY = Weighted Average VL = -1 01og 1 0(AWRVL) This will g ive an approximation of the vertica l i l l u m ina nce at point p. (With distance in meters, illuminance will be in lux.) However, a more accurate calculation will include reflected lig ht, which can be most easily achieved with l ighting software that performs radiosity or ray-tracing calcu lations. Additional information on Small Ta rget Visibil ity can I nverse Sq u a re Law be found in several of the references in the Additional Vertical Su rfaces Reading section at the end of this chapter. E - I 3.8 Vertical l l l uminance y Vertical il l u minance-the l ight fal ling onto a vertical su rface, such as on pedestrians and bicycl ists-is v I coso n2 -- D H important, both so that they can see each other and so that they can be seen by motorists. It is especia l l y helpfu l i n facial recog nition. Recommendations for i ll u m i nance in a vertical plane R N ormal p will need to specify the location of the plane (e.g., Figure 3-19. Calculating illuminance on a vertical surface height above the grou nd) and the direction that the - d i rect component. (Graphic redrawn from original, l ight meter is facing. Because i lluminance on a surface courtesy of FHWA Lighting Handbook, 2012) 3-30 Calculations l u minance as a result of l ight received d i rectly from 3.9 Tu nnel Calculations a given luminaire. This e lement l u minance wi l l be 3.9.1 General. Methods for assessing the quantity of dependent on lum inaire candlepower, l u m inaire­ l ight coming directly from a l u m inaire to a given point element geometry, su rface element reflectance, are d escribed i n Section 3.4 and direction of reflection. This can be referred to - llluminance. The l ight as the first-reflection l u minance. level in a tunnel will be higher than what is indicated by direct calcu lations because of the contribution of • The points on the roadway at which pavement light reflected and i nterreflected from the tunnel 's lum inance are calcu lated will receive l ight both surfaces. The degree that the reflected l ight contri butes d i rectly from the l u m i na i res and indirectly from the to the l u m i nance of the i nterior tunnel su rfaces varies with the su rfaces' location, geometry, and maintained walls and ceiling. Thus, the computation algorith ms reflectance va l ues. indirect contri butions. This section describes a process suitable for calculating will be more accurate if they include the add itional • which may be rectangular, or a variety of other d i rect and reflected light contributions to the l u m inance shapes i ncorporating sloped or cu rved su rfaces. of tunnel su rfaces for straight tunnel sections. • This section is not intended to prescribe the only calculation method available or acceptable. Software that provides ful l radiosity solutions and includes consideration of obstructions is an acceptable means for calculating a tunnel 's interior lighting. It is the responsibility of the designer to know the method and limitations of the An i mportant variable is the tunnel cross-section, The su rface area l u m ina nce will be increased above the fi rst-reflection l u m i na nce because of light received from other su rface areas that are also receiving and reflecting light. Thus, the su rface area l u minance is due to the second and su bseq uent reflections-that is, the i nter-refl ection of light between a l l of the various d iscrete su rface elements. calculation procedure used and to design the tunnel lighting system with these limitations in mind. Calcu lation of the horizontal i ll u m i nance or pavement Before the d esign calcu lations are started, the following following seven steps: l u m i nance at a point on the roadway req uires the 1 . Calcu late the d i rect component from the first should be d etermined: • Lumina nces required i n the tunnel 's threshold, l u minaire using the inverse-sq uare-cosine law, and transition, and interior zones (see Chapter 14, the existing methodology (see Section 3.4). Section 1 4.4) • 2. Repeat for a l l other lum inaires, and sum the val ues Acceptable u niformity ratios (see Chapter 14, to calcu late the total direct component from the Section 1 4.4.6) entire l ighting system. 3. Subd ivide the walls and ceiling into elements. These • Light sources to be used • Lumina ire types and photometric characteristics • Light l oss factors (see Section 3.1 .6 in this chapter) The standard methodology for tunnel ana lysis is based on finite element tech niques. In order to develop a methodol ogy for hand l i ng l u m i nance calculations in tun nels, an understanding of several factors and relationships is required: • elements will reflect l ight from each l u minaire to the pavement computation point. Identify the size and center-point location of each e le ment. 4. Calculate the i l l u m inance in the plane of the first element at the element center point by summing the contri butions from each l u m i na i re. Repeat for each element. 5. By applying the element reflectance fu nction, The su rface of the wa l ls and ceiling a re split calcu late the intensity reflected by the element to into flat fin ite elements that closely or exactly the pavement observation poi nt. match the tunnel geometry, a process known 6. Treat each element as a l u m i naire by using the as "d iscretization." A given element will have a calcu lated intensities to determine the pavement 3-31 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities com putation point i l l u m i nance and l u m i nance from the method for defi n ing the calculation zone using the existing methodology (see Section 3.3), for the i nterior (and nig htti me). Figure 3-20 shows summing for all contributing elements. the calcu lation g rids for the threshold and tra nsition zones. Figure 3-21 shows the calculation grid for the 7. Repeat steps 4, 5, and 6 to determine the total i nterior zone and nig httime. While exact rules cannot indirect component for the first reflection for each be specified for a l l situations, this discussion is i ntended pavement observation point req uired. to i l lustrate the principles that should be fol lowed in selecting grids for calculation. Details of these steps are outlined below. Note: Even though the lighting metric for tunnels is 3.9.2 Selection of a Grid for Tunnel Lighting Calculations. l u m i nance, i ll u m i nance can be used to val idate l u m i naire Different proced u res a re req u i red performa nce. The same grid points that are esta bl ished when selecti ng a grid for tunnel zones. A tunnel has for l u minance can be used for illuminance. basical ly three zones: threshold, transition and i nterior. The method for defi ning the calcu lation grid for the 3.9.2.1 Straight Tu nnel Pavement - Luminance. threshold and transition zones is sl ightly different series of calcu lation points shall be esta blished withi n - - - - - - - - - Travel Direction - - - - - LANE a .. -- - ------ Travel D1rect1on LANE d Threshold or Transition Zone P LAN V I E W { Calcu latio n point height a bove floor �r 1 .75 m 1.2Sm 0.7S m 0.2S m + + + + + + + + + + + + + + + + + + + + + + + + WALL V I EW Figure 3-20. Calculation grid for threshold zone or transition-zone tunnel calculations. In the Plan view (top image), point a indicates the meter position, which will be at the height and the distance from the measurement point given in Table A-1 (see Section A.3.3 in Annex A). The grid length, d, is one-fourth of the entire zone length and occurs in the first half of the zone. (Graphic courtesy of Ray Yeager) 3-32 A Calculations - - I - Travel D1rect1on LANE a ..- ----+ -- Travel D1rect1on ------- LANE Typical interior or nightime measurement area P LAN V I EW Ll f Height of calculation point above road �r � + + + + + + + + + + + + + + + + + + + + + + + + WALL V I EW Figure 3-21 . Example of measurement geometry for the interior (or nighttime) zone. In the Plan view (top), point a indicates the meter position, which will be at the height and the distance from the measurement point given in Table A-1 (see Section A.3.3 in Annex A). (Graphic courtesy of Ray Yeager) each zone on the road su rface as i l lustrated in the top d istance between the centers of the elemental areas images in Figures 3-20 and 3-2 1 . Each calculation point does not exceed 2.5 m. Luminance and illuminance (shown as a green cross) represents the center of an calcu lations sha l l be made on road su rface. lllu minance elemental area (shown as a blue box). The beginning calcu lations sha l l be made on the wal ls. The ratio of and end of the elemental area should fil l the calculation road to wa l l average i l l u m inances shall be used to area without extending beyond the area. There sha l l demonstrate complia nce with the maximum ratio of 2.5 b e three calcu lation points across each lane s o that the described i n Chapter 1 4, Section 14.4.4. elemental areas fit within the lane bounda ries. For the i nterior (and nig httime) zone, the calculation The calcu lation grid for the threshold and transition area should be far enough into the zone that it is zones should be selected such that, for straight tunnel representative of the bala nce of the tunnel. The sections, the typical calculation area is equal to one­ calcu lation typical a rea sha l l be bounded by the fourth the zone length and located i n the first half of the l u m i naire locations. In the i nterior zone, the typica l zone. Zone length will affect the longitudinal spacing area beg ins and ends at the l ocations of a cycle of of the calcu lation points in the threshold and transition interior l u minaires. Similar to the typica l area in the zones. The length of the elementa l areas will vary threshold and transitions zones, the element areas fi l l slightly to satisfy the requirement that the combined the calcu lation area, but i n this case, the area i s defined length of the elemental areas fills the ca lculation area by the l u m i naire cycle. The distance between the centers without extending beyond it and ensuring that the of the elemental areas sha l l not exceed 2.5 m. 3-33 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 3.9.2.2 Cu rved Tun nel Pavement - llluminance. Curved roadway sections in tunnels can be calcu lated with the horizontal i ll u m i nance method, using a rectangular grid with a spacing of no more than 2 meters by 2 meters on the travel la nes. The l ight levels can be derived using the i l l u m inance-lum inance equ iva lencies given in Section 3.2 for the pavement classification under consideration. 3.9.2.3 Tunnel Walls - llluminance. Along the wall, measurement locations for the tunnel walls shall line / up with measurement locations on the road surface, as i l l ustrated in the middle and bottom i mages in Figures 3-20 and 3-2 1 . A grid of four measurement points shall be at 0.25, 0.75, 1 .25 and 1 .75 m from the base of the wal l . 3.9.3 Computation of t h e Direct Component. The i l l u m i nance or pavement l u m inance created by direct l ight received from a l u m inaire can be computed i n accordance with the existing methodology; i.e., i n a manner identical to that used for roadway lighting / / / / / /. . � / t i' cl-�o; R � � -, J" The refleEtance angles for a ce i l i ng-mount_e-9 luminaire Figu re 3-22. The reflectance angles for a ceiling­ mounted luminaire.14 (see Sections 3.3 and 3.5). Poi nt-by-point tabulations can thus be prod uced. In this procedure, y and ¢ are the horizonta l and vertical photometric angles, respectively, of the l u m inous i ntensity /. These are �------.. ' measured, respectively, from a lateral reference l i ne perpend icular to the curb and from nadir. t Figure 3-22 illustrates a level cei l ing-mounted tunnel I I luminaire, showing identical coord inate convention to y /--..... -, l�.Y) I Lewin and Hei nisch. 1 3 Figure 3-23(a) is derived from I v=<> Figure 3-22 and is to be compared to Figure 3-23(b), which represents the photometric angles applicable to a vertica l ly positioned wa l l-m ou nted l u m i na i re. The reference zero vertical angle is always the nadir pho1ometrlc angles for a (a ) The cefling-mounted luminaire d i rection, extending vertica l ly d ownward from the l u minaire; it should be confirmed that the l u minaire has been photometered in this mounting orientation before proceeding with the calcu lations. Otherwise, an angle of ti lt will need to be appl ied to the luminaire so that the software will calculate the proper results. 3 .9.4 Discretization of the Tu nnel Surfaces. Subd ividing, or discretizing, the tunnel wal ls and cei ling into element al lows calcu lation of the interreflected components by treating each surface element as a ( b) The pho1ometric angles for a wall-mounted lumlnaire receiver of l ight from the l u m i na i res and a reflector of Figu re 3-23. The photometric angles for a ceiling­ l ight to the pavement computation points. mounted luminaire (a) and a wall-mounted luminaire (b). 3-34 Calculations In the simplest case, a tunnel with a rectangular cross­ section, vertica l surface elements can be devel oped by subdivid ing each wa l l horizonta lly and vertical ly, and horizontal elements are formed on the cei l i ng by subdividing lateral ly and longitudinal ly. In the case of a tunnel with angled or cu rved surfaces, the su rfaces can be subdivided and approximated by a series of flat elements with d iffering sl ope angles. The size of the su rface elements, both width and length, should be chosen in developing the interreflection scheme. The use of a very large n u m ber of small elements will provide a high degree of accuracy but may require excessive time i n performing the reflected l ight calcu lations. Conversely, large elements may provide less accuracy but can reduce computation time. Figu re 3-24. The general geometry for a surface element. Ideal ly, element sizes are chosen that are small enough not to compromise computational accuracy but large enough not to needlessly lengthen computation time. The sizes of the wall and ceiling elements req uired A E is perpendicular t o the surface element for accu rate computation vary dependi ng on tunnel L AC is horizontal and parallel to the x axis geometry and the form of the lighting system. The use of l uminaires with asymmetric photometry tends to req u i re smaller elements. It is recommended that calcu lations be performed on an iterative basis until the i mprovement in accuracy obta ined by going to smaller elements is negl igi ble. 3.9.5 Computation of the Indirect Component of llluminance. Figure 3-24 ill ustrates the geometry of The luminaire (L) and surface element geometry that defines e a reflecting wal l or cei l i ng su rface element receiving a l ight ray of l u minous intensity /(¢>,y) from lum ina ire L. Figure 3-25 shows the identical reflecting element and Figu re 3-25. The luminaire (L) and surface element additional construction lines, indicating that it l ies at a geometry that define 0. slope angle, S, from the vertical . The va lue of S is general x coordi nate of the l u m i naire minus the x and therefore can be used to represent elements on the coord inate of the element center point. left wall, cei ling, or right wa l l . (Slope angles for right wa l l elements are negative.) Yo y coordi nate of the l u m i naire minus the y To perform the computation, x, y, and z coordi nates Zo z coord inate of the luminaire minus the z coord inate of the element center point. a re req uired for the l u m i na i re, the reflecting zone coordinate of the element center point. center point, and the pavement computation poi nt. x coordi nate of the pavement From these coordi nates, x0, Yo, ' z0,, x 1 , y 1 , and z 1 are computation point minus the x coordi nate determ ined, defined as fol l ows: of the element center poi nt. 3-35 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities y coord i nate of the pavement y1 computation point minus the y coordinate e = cos - 1 of the element center point. Height of the element center point above the pavement computation poi nt. </J and y are computed: ( ), - Yo '+' = tan 1 x.; (3-6) In the case of a vertical element, the slope angle S = go0, a n d e is then is given by: Given these dimensional quantities, the values of ang les A. (�) , for S = 0° , (3-1) e = cos - 1 (.BJ· for S = 90° , (3-7) The va lue of e should compute to �go0 in a l l cases. 3.9.6 Computation of Surface Element Luminance (3-2) and Reflected Intensity. By applying the reflectance fun ction of the element su rface, the e lement l u m inance The va lue of S, the slope angle of the reflecting e lement measured from the su rface normal to the downward vertical, will be known from tunnel geometry. For the general case of any given l u m i naire location and a known location and slope angle of a defined reflecting can be obtai ned. From th is, the reflected intensity from the element in a ny particular direction can be found. If Lo is the element luminance: element, the illuminance at the center of the element (3-Sa) and i n the plane of the element, £0, is given by: If f(r) is the bidirectional reflectance d istri bution E o = I(</J, y) cos e ' (3-3) D� a n d reflection, Lo will represent the element l u m ina nce as viewed by an observer from the particular direction where: Do = fu n ction (BRDF) for the appropriate angles of i ncidence d istance from the l u m inaire to the of reflection. £0 is assumed to be un iform over the element center point. element, a lthough it is normally calculated for the center poi nt. (More-rigorous calcu lations can be made where Eo is calculated by the same above-described £0 can be calcu lated using: D0 = vx0 2 2 2 + Y 0 + Zo ' manner at numerous poi nts over the su rface element, (3-4) a n d the va lues then may be averaged.) Equation 3-Sa can be used to d eterm ine the wa l l and: 8 = cos- 1 [(x0 - 'ti cotS)/D0 cscS] , l u m i nance a t any poi nt, using Equation 3-3 t o calculate (3-5) where: 0° < s < 90° Eo at that point. Determination of the d iffuse component of reflectance is n ormally sufficient for tunnel l ighting computations, and the relationshi p then becomes: Information concerning the derivation of Equations 3-3, 3-4, and 3-5 is provided in Lewin and H einisch. 1 3·1 5 (3-8b) I n the case of a horizontal element, the slope angle S = where: 0°, and the cosecant and cotangents are indeterm inate. p e then reduces to: 3-36 1t diffuse reflectance factor pi (approxi mately 3.141 Sg) Calcu lations La is l u minance, in cd/m 2 and the line from the element center to the roadway Ea is illuminance, in lux calculation point, then: Use of the d iffuse reflectance provides a nother (3-10) simplification: The l u m i nance pattern on the tunnel su rface will be i nd ependent of the location of an where: observer viewi ng the element d i rectly, u n l ike the case /0 is the intensity reflected by the surface element where the BRDF of the su rface is applied. Later practices, to the pavement calculation point. however, may incorporate the use of BRDFs. To determine reflected i ntensity i n a specified d i rection, If D 1 is the d istance from the element center point to the pavement calculation point, cos 8 may be expressed as: the i ntensity perpendicular to the su rface element is first found: cos/5 X1 + Z1 cots cscS D I • ' ior • oo < s < 900 , (3-1 1 ) (3-9) I nformation concerning t h e derivation o f t h e form ula for cos 8 is provided in Lewin and H einisch. 12•1 3 where: La perpendicu larly reflected intensity, in cd zone l u minance, in cd/m 2 Ao zone size, in m 2 I' Figure 3-26 i l lustrates the geometrical relationships between the su rface e lement a n d a pavement In the case of a horizontal element, S = 0° and the fu nctions are indetermi nate. The value of cos 8 can be found from: z, cos8 = D , for S I (3-12) oo , calculation point. If 8 is the angle between the normal to the surface (direction of perpend icu lar i ntensity !') cos8 = AF is perpendicular to the surface element AJ is horizontal and parallel to the x axis � , for S = 90 ° , If the element is vertical, S = 90° and cos 8 becomes: x (3-1 3) I Su bstituting the va lue of cos 8 into Equation 3-10, along with the va lue of I' as calculated from Equations 3-Sa, 3-Sb, and 3-9, /0 is found. The e lement center is treated as a l u m inaire with known coordinates and intensity /0. Thus, the i l l u minance and luminance of the pavement calcu lation point can be found by the 11 I conventional method, as d escribed for roadway l ighting in Sections 3.3 and 3.5. This procedure is applied to a l l elements, and t h e val ues a r e sum med t o d etermine the total ind irect component due to the first reflection for z pavement illu minance and l u mi nance. The surface element and pavement observation point geometry that defines Ii Veiling Luminance. Tu nnel su rfaces of high reflectance 3.9.7 Computation of the Indirect Component of may contribute to the level of veiling l u m ina nce. The Figure 3-26. The surface element and pavement contribution to the vei ling luminance at the eye can be observation point geometry that defines 6. determined for each wall and cei ling su rface element. 3-37 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Qua ntities x2 , y2 , and z2 are defined as follows: x coord i nate of the observer's eye minus z , + Z 2 + cots COSe = cscS · D , the x coord inate of the element center , for 0° < S < 90° , (3-15) poi nt. y coord i nate of the observer's eye minus I n the case of a horizontal surface element, S = 0° and the y coord inate of the element center the functions are indetermi nate. The value of cos e can poi nt. be found from: Height of the element center point above the observer's eye. These qua ntities are shown i n Figure 3-27. If e is angle cose = I ' COSe ' cose (3-14) oo , (3-16) If the element is vertical, S = 90° and cos e becomes: between the perpendicular to the su rface element and the line to the observer 's eye, then: z2 D2 , for S z 2 =0 , for S = 90° , 2 (3-17) Su bstituting the value of cos e in Equation 3-14, along with the va lue of I' as calcu lated from Equations 3-8 and 3-9, /, is found. The element center is treated as where: I, the i ntensity reflected by the element to the observer's eye, i n cd I' the perpendicularly reflected intensity, in cd a l u m i naire with known coordi nates and i ntensity /,, a n d computation of veiling l u minance at the observer's eye location is found by conventional methods. 1 6 The procedure is appl ied to all su rface elements, and va l ues are summed to determine the total veiling l u minance If D 2 is the d istance from the element center point to the created by the first reflections from the tunnel wa lls observer's eye, cos e may be expressed as: a n d cei l ings. AF is perpendicular to the su rface element 1I ������;��h�iid�tfi���. The su rface element and Figure 3-27. The surface element and observer location point geometry that defines E. 3-38 Calculations A DDITI O N A L RE A D I N G Note: This section is not part o fANSI/JES RP-8-27. It is included for informational purposes only. Anderson KA, Hoppe WJ, McCoy PT, Price R. 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International Commission on I l l um ination (CIE). CIE Report 30.2, Calcu lation and Measurement of Luminance and l lluminance in Road Lighting. Vienna: CIE; 1 982. 3. Illuminating Engineering Society. ANSl/IES TM-2 1 -1 9, Technical Memorandum: Projecti ng Long Term Lumen Maintenance of LED Light Sources. New York: IES; 201 9. 4. Illuminating Engineering Society. IES RES-1 -1 6, Measu re and Report Lum i naire Dirt Depreciation (LDD) in LED Lumina ires for Street and Roadway Lig hti ng Appl ications. N ew York: I ES; 201 6. 5. JMU Office of Public Safety. Detection and safe stopping d istances. Ha rrisonburg, Virg.: Ja mes Madison Univ.; Oct 2009. 6. Roper VJ, Howard, EA. Seeing with motor car headlamps. Tra nsactions of the l l l u m i n Engineering Soc. 1 938;33(5):417-38. 7. Johansson G, Rumar K. Visible d istances and safe approach speeds for n ight d riving. Ergonom ics. 1 968;1 1 (3):27582. 8. Hasson P et al. Trees, l ighting, and safety in context-sensitive sol utions. Transport Res Board. 2009;21 20:1 01 -1 1 . 9. Va nBommel WJ, deBoer JB. Road Lighting. Kluwer Techn ische Boeken B.V. - Deventer; 1 980. 1 0. Northwest Energy Efficiency Alliance. Seattle LED adaptive lighting study. Portla nd, Ore.: NEEA; 201 4 May 29. (N EEA Report #El4-286). 1 1 . Vos JJ. On the cause of d isabi l ity glare and its dependence on g lare ang le, age and ocu lar pigmentation. Clinical and Experim Optom . 2003;86:363-70. DOI: 1 0.1 1 1 1 /j.1 444-0938.2003.tb03080. 1 2. Gibbons RB, Edwards CJ. A review of disability and d iscomfort glare research and future direction. Washington, DC: Tra nsportation Research Board; 2007. 1 3 . Lewin I, Hein isch RV. Lumina nce calcu lations for tunnel l ighting systems. J Ilium Engr Soc. Winter 1 988:74-9. 14. American Association of State Highway and Tra nsportation Officia ls. AASHTO G-5, An I nformational Guide for Roadway Lighting. Washington, DC: AASHTO; 1 984. 1 5 . Lewin I, Hein isch RV. Further devel opments in tunnel l ighting computations. J I l i u m Eng Soc. Winter 1 991 :1 00-7. 1 6. Illuminating Engineering Society. IES LM-7 1 -1 4, Approved Gu ide: Photometric Measu rement of Tu nnel Lighting Installations. New York: I ES; 201 4. 3-41 O btrusive Light Cha pter 4 CO N T E N TS 4.1 4.2 4.3 I ntroduction 4-1 Defining Obstrusive Light . . . . . . . . . . . . . . . . . .4-1 4.6 Light Trespass . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-2 4.7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . of Spill Light . . . . . . . . . . . . . . . . . . . . . . . . 4-4 I mpacts From Off-Roadway Obtrusive Light 4-9 Some Cond itions Wherein 4.7. 1 Obtrusive Light M ight Be Created for Road Users . . . . . . . . . . . . . . 4-9 M itigation of Spill Light . . . . . . . . . . . . . 4-5 4.7.2 4.3. 1 Recom mended Accepta ble 4.3.2 Measurement and Calcu lation . . . . . . . . . . . . . . . . . . . . . . . . . . . Levels of Spill Lig ht . . . . . . . . . . . . . . . . . . 4-3 4.3.3 4.4 Glare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5 M itigating the Effects of Obtrusive Light From Off-Roadway Sources . . . . 4-9 4.8 4.9 Lighting I mpacts on Species and Habitat . . 4-9 Potential Health I mpacts of Lighting on Humans . . . . . . . . . . . . . . . . . . . . . .4-1 0 Sky Glow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5 Sources of Sky Glow . . . . . . . . . . . . . . . . . 4-6 4.1 0 I mpacts of Exterior Lighting on Airports . . .4-1 0 4.5.2 References for Chapter 4 4.4.1 Calcu lation and Measurement of Offsite Glare . . . . . . . . . . . . . . . . . . . . . . 4-5 4.4.2 4.5 4.4.3 M itigation of Sky Glow . . . . . . . . . . . . . . 4-7 Obtrusive-Light Regulations . . . . . . . . . . . . . . 4-8 M itigation of Glare . . . . . . . . . . . . . . . . . . 4-5 4.5. 1 Sky Glow Models . . . . . . . . . . . . . . . . . . . . 4-7 . . . . . . . . . . . . . . . . . . . . . • . .4-1 1 Chapter 4 O btrusive Light T his chapter contains basic information regarding obtrusive light and how the effects ofobtrusive light can be mitigated. The main objective with respect to obtrusive light should be to light the area intended to provide appropriate levels of visibility for roadway users while reducing and minimizing lighting impacts to those outside of that area. 4.1 I ntroduction In the past, many l ighting insta l lations were designed with l ittle or no thought to obtrusive light. However, there is growing i nterest by commun ities, homeowners, and special i nterest groups such as the International Dark-Sky Association (I DA) to red uce obtrusive light. Lighting d esigners should be know ledgeable with • Light trespass • Glare • Light pollution In general, obtrusive l ig ht is any l ight that is d iscerned beyond the intended target area, and which by its respect to obtrusive light, related standards and criteria, nature or presence is obtrusive to ind ividuals, is harmful and proven tech niques for its m itigation, as the desire to to the environment, or contributes to sky glow. The avoid obtrusive light. elements of obtrusive light are depicted in Figure 4-1 a n d are fu rther defined in their individual sections of this chapter. In addition, this chapter also i ncludes 4.2 Defin i ng Obtrusive Light sections on the related issues of Lighting Impacts on Obtrusive l ight is defi ned by three major i nterrelated Species and Habitat (Section 4.8), and Potential Health elements, each considered separately: I m pacts of Lighting (Section 4.9). Sky G l ow (Lig ht Po l l ution) (Visual Haze Caused from U p li ght Reflected off Particulates Suspended i n the Atmosphere) S p i l l Light Spi l l Lig ht �t Residence I ntended Ta rget Area Property Line Not to Sca le Figure 4-1 . T h e components o f obtrusive light (not t o scale). 4-1 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Exa mples of typica l obtrusive l ight situations include: Spill l ight is an increasing issue as exterior lighting Local residents who register complai nts about a instal lations increase. Severe problems may have been bright street l ight visible in their windows addressed by shielding or re-aiming offending luminaires, Local residents who register complaints about or by using different luminaire types and dimming. • • i l l u minance fa l l i ng onto their property • An astronomer who notes that the view of celestial objects is obscured by the presence of or an increase in sky glow • Roadway users who register complai nts about off­ roadway l ight sources that impact visibility, such as large advertising signs or lig hted sports fields • In a n effort to solve the problems caused by spi l l light, various communities are now adopting outdoor l ighting ord inances or regu lations. Some of these specify measurable limits for light trespass in terms of horizontal or vertical i l l u m i nance at or within property lines. However, illu minance limitations may not address the issue as wel l as l ight source luminance or intensity l imits. Stray l ight that affects flora (causing u n natural growth or stress) or fauna (inhi biting normal nocturnal activities) Wh i l e illuminance regu lations enable easy measurement by m u nicipal officials, they do l ittle to help those who are troubled by a "bright" l u m i naire that may be l ocated blocks, or even mi les, away in an otherwise dark field 4.3 Light Trespass of view. Candela l i mitations at offsite viewing ang les Light that strays from its intended pu rpose can become would minimize the brig htness effects. a visual annoyance, or even tem porari ly d isabling. The term light trespass, someti mes called spill light or stray It is important to note that the maximum vertical light, is used to describe this effect. The spread of l ight illuminance levels that define spill light are based on poll ution, or sky glow (see Section 4.5), and spill l ight research using human subjects where a variety of are closely connected. Most complaints about spi l l l ight individuals were subjected to various light levels in come from people u pset by u nwa nted l ight entering their windows or intruding upon their property (see, controlled situations.1 The maximum vertical illuminance levels vary depending on the lighting zone2 (see Section for example, Figure 4-2). Similar conditions occur 4.3.1). This research and the corresponding maximum when stray l ight from private property briefly impairs levels are therefore based on human sensitivity to light and vision for automobile d rivers. I n m ost cases, the are applicable in areas and situations of human habitation. problem is tracea ble to poorly ai med or otherwise These requirements should not be applied to situations high-glare l ighting equipment. Inappropriate l u m inaire where insects, plants, animals or other environmental maintenance can resu lt in components of the system issues are the chief concern, as this research is not relevant being replaced incorrectly or adj usted a n d a imed to those situations. (Refer to ANSl/IES LP-1 0-203 for effects i mproperly. of electric lighting on animals and plants.) I mportant exceptions to controlling spi l l light to withi n t h e recommended levels may exist. This is true i n situations where l ighting o f areas adjacent t o t h e road al lowance provides for a greater degree of safety by enhancing the periphera l vision of roadway users. These situations may i nclude rural areas with unmarked d riveways and areas where col l isions between wildlife a n d a utomobi les exist or are anticipated. I n these insta nces, i l l u m i nation of the peripheral areas may be a recognized safety factor and included in design criteria as l ong as it is desig ned to achieve the expected resu lts Figure 4-2. Example of a spill light situation. 4-2 without over-lighting unintended areas. Obtrusive Light 4.3.1 Recommended Acceptable Levels of Spill Areas are classified into one of five LZs, ranging from Light. LZ-0, the most restrictive, to LZ-4, the least restrictive, The IES and the IDA together have defined maximum levels of spi l l l ight with in given areas of ambient brig htness. Known as lighting zones (LZ), these area classifications are being recognized and utilized by professional organizations and adopted in lighting as shown in Table 4-1 . (Refer to ANSl/IES LP-1 1 -202 for i n-depth discussion on lighting zones, including a d iscussion on "How to Use Lighting Zones," and frequently asked questions that need to be addressed whenever the use of l ighting zones is proposed.) ordina nces. ANSl/IES LP-1 1 -202 and the I ES/IDA Model Lighting Ordina nce4 provide g u ida nce for developing a Recommended acceptable maximum initial illuminance com mu nity lighting ordinance. levels of light trespass based on LZs are shown in Table 4-2. Table 4-1 . Lighting Zones Zone 0 Recommended Uses or Areas Considerations Lighting Zone O should be appl ied to areas in which permanent Recommended default zone for wilderness lig hting is not expected and when used, is l i m ited i n the amount areas, parks and preserves, and of lighting and the period of operation. LZ-0 typica l l y includes undeveloped rural areas. undeveloped areas of open space, wilderness parks and preserves, areas near astronomical observatories, or any other area where the I ncludes protected wildlife areas and corridors. protection of a dark environment is critica l . Special review should be req uired for a ny permanent lig hting i n this zone. Some rural com m u n ities may choose to adopt LZ-0. 1 Lighting Zone 1 pertains to areas that desire low a m bient Recommended default zone for rural and lig hting leve ls. These typica l l y include single and two fa mily low density residential areas. residential com m u n ities, rural town centers, business parks, and other commercial or industrial/storage areas typically with l i m ited Includes residential single or two fami ly; nighttime activity. May also include the developed areas in parks agricultural zone districts; rural residential zone and other natural settings. d istricts; business parks; open space include open space include preserves i n developed areas. 2 Lighting Zone 2 pertains to areas with moderate a m bient Recommended default zone for light lig hting leve ls. These typica l l y include mu ltifamily residential uses, commercial business districts and high institutional residential uses, schools, churches, hospitals, hotels/ density or mixed use residential districts. motels, commercial a nd/or businesses areas with evening activities 3 em bedded i n predominately residential areas, neighborhood I ncludes neighborhood business districts; serving recreational and playing fields a nd/or mixed use churches, schools and neighborhood development with a predominance of residential uses. Ca n b e used recreation facilities; and light ind ustrial zo ning to accom modate a district of outdoor sales or ind ustry i n a n area with modest nig httime uses or lighting otherwise zoned LZ-1 . requirements. Lighting Zone 3 pertains to areas with moderately high lighting Recommended default zone for large cities' levels. These typically include commercial corridors, high intensity business districts. suburban com mercial areas, town centers, mixed use areas, ind ustrial uses and shipping and ra i l yards with high night time I ncludes business zone districts; commercial activity, high use recreational and playing fields, regional shopping mixed use; and heavy ind ustrial a nd/or malls, car dealerships, gas stations, and other n ightti me active manufacturing zone d istricts. exterior retail areas. 4 Lighting Zone 4 pertains to areas of very high ambient lighting levels. Not a default zone. LZ-4 should only be used for special cases and is not appropriate for most cities. LZ-4 may be used for extremely unusual installations such I ncludes high intensity business or ind ustrial as high density entertainment districts, and heavy industrial uses. zone districts. 4-3 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Table 4-2. Recommended Maximum Initial Vertical llluminance Spill Light from Exterior Lighting, Based on Lighting Zone Lighting Zone S iolcfng Cena Maximum Initial Vertical llluminance, lux (fc)* LZ-0 0.5 (0.05) LZ-1 1 .0 (0.1) LZ-2 3.0 (0.3) LZ-3 8.0 (0.8) LZ-4 1 5.0 (1 .5) Table note: • Max i m u m at any point in the vertical plane of the property line. Figure 4-3. Construction of a shielding cone. 4.3.2 Measurement and Calculation of Spill Light. Because spill l ight is based on i l lu mi nance, it is both 4.3.3 Mitigation of Spill Light. In u rban residential quantifiable and easily measu rable using an illum inance areas where spi l l l ight is a concern, it can be m itigated­ meter. It is also easily calcu lated using lighting design but not elimi nated-through careful photometric software. ana lysis using a trial and adjust process. This process will involve experi menting with va rious mounting Research findings indicate that horizontal spill l ight heig hts and l u m i na i res with va rious l u men outputs, (that is, l ight measured with the meter photocel l l ight distributions, and shielding options. An exa mple receptor positioned parallel to the ground) is not the of a n external shield is shown in Figure 4-4. (Note the key objectionable component with respect to spi l l light. l u m i na i re in the distance without the shield.) If the l ight Rather, vertica l i l l u m inance Ev, perpendicular to the l i ne d istribution from the l u m inaire exceeds the lim itations of sight is the most significant issue. noted in Table 4-2, the designer should consider selecting a l u m i na i re with a different light distribution In practice, the measurement of spill light ca n be pattern and adjusting the mounting height and l u men undertaken with a ca librated il l u mina nce meter by output to achieve the desired result, while ensuring that taking measu rements at the property bou ndary line or the roadway l ighting criteria are not compromised. the edge of the road allowance as described in Table 4-1 (Section 4.3.1 ). To block out extraneous light, a shielding cone 1 0 cm in length that can be constructed from flat b lack paper is attached over the meter's photocell receptor. The cone can flare outwa rd up to five degrees. A d rawing showing the construction of the cone is shown in Figure 4-3. The Ev measurement is accomplished by orienting the shielded meter's receptor towa rd the source of the objectionable l ight from a height of 1 .5 to 1 .8 meters above grade (approximate eye height for a standing adult) and recording the illuminance reading in lux. By comparing the reading to the value for the applicable LZ in Table 4-2 (Section 4.3.1), the designer is able to confirm whether a Figure 4-4. Roadway luminaire equipped with an light trespass noncompliance issue may exist. external shield. 4-4 Obtrusive Light For existing facil ities where complai nts from citizens methods. In roadway lighting design, glare is usually ind icate a problem, a nu m ber of approaches to measured and calculated as the veiling l u minance ratio m itigation or correction exist. or threshold increment (see Section 3.6). Lighting system mod ifications for correcting l ight 4.4.2 Mitigation of G lare. Offsite g lare can be m itigated trespass situations i nclude: by shielding the view of bright l ight sou rces from the • • I nstal lation of external shields on the existing observer. This can include adjusting mounting heights, luminaires decreasing l ight source lu mens, using l u minaires with Replacement of the l u m i naire with one that has low-G BUG ratings (see Section 2.6.1), using internal or minimal g lare • Di mming the l ighting external shield ing, or d imming. Because l u m inaire optical systems can have a direct If mod ification or replacement of the l u m i na i re is considered, the owner or owner's representative should perform calcu lations to confirm that the design criteria are stil l met. im pact on glare, l u m i naires with well-desig ned optics are recom mended to reduce glare effects. Specifically, the l ight em itted between 70 and 90 degrees above nad i r tends to be the most problematic. It is also recom mended for roadway lighting designs that vei l ing l u m i nance recom mendations not be exceeded. (Refer to Chapter 10 - Roadway and Interchanges for more 4.4 Glare G l a re is defi ned 1 as the sensation prod u ced by l u m i nances within the visual field that are sufficiently g reater than the l u m i na nce to which the eye is adapted to cause annoyance, d iscomfort, or loss in visual performance or visibil ity. Chapter 2 - Vision and information on veiling l u minance criteria.) High-mast l ighting req uires special considerations with respect to glare because the mounting height of the l u m i na i re makes the light sou rce visible to a large area. Luminaire l ight d istribution, shielding, location, and Fundamental Concepts describes d isabi l ity glare and lumen output are critical design considerations for d iscomfort glare. mini mizing glare (Refer to Chapter 6, Section 6.2.4 High-Mast Lighting for more information.) Glare viewed offsite is often the single biggest concern when obtrusive l ight is d iscussed, since the eye and the attention of the observer are attracted to bright objects. 4.5 Sky Glow Sky glow is the term used to describe the added sky The effect of glare is increased with the contrast of a brightness caused by the scattering of electric l ight into black night sky and l ittle or no ambient lighting. This the atmosphere, particularly from outdoor lighting in u rban areas. 1 concept may be understood by imagining oncoming veh icle headlig hts viewed i n dayl ight compared with how they appear at night. The l ight output and i ntensity Professional and amateur astronomers were among the are the same, but the headlig hts appear brighter at first to see the effects of sky glow origi nating from u rban night when seen agai nst a dark background and with and surrounding areas. Professionals using commercial the eyes adapted to a much lower l ight level. telescope sites, such as those at Mt. Palomar in Cal ifornia, Kitt Peak i n Arizona, and Mauna Kea in Hawa ii, and 4.4.1 Calculation and Measurement of Offsite Glare. a mateurs using more conventional equipment have a l l Glare is expressed in terms of l u minance (candelas per reported increased visual impairment when viewing the square meter, cd/m2). Offsite glare can be field measu red, stars and other celestia l phenomena. but the measurements are difficult and require expensive luminance meters. It is possible to calcu late offsite glare While amateu r astronomers do not have the large, using lighting design software or hand calcu lation soph isticated e q u ipment e m p l oyed by major 4-5 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities observatories, they do use equi pment of high qual ity, which becomes scattered in the atmosphere. The result and amateurs often make d iscoveries that are passed is a l u m inous a u ra, or sky glow, over cities. on to professional researchers for fu rther study. Despite the development of sophisticated telescopes such as A brief overview of sky glow is covered in the su bsections H u bb le, there is an ongoing need to continue the that fol low. Additional i nformation may be found i n use of esta blished land-based telescope sites and the ANSI/JES TM-37-27, Technical Memorandum: Description, im portant role of amateu r observers. Measurement, and Estimation of Sky Glow. 5 Astronomers are particularly concerned about light 4.5.1 Sources of Sky Glow. d i rected above the horizontal as wel l as reflected lig ht, chief concern with respect to sky glow because of its Roadway lighting is a Figure 4-Sa. Composite photo of the earth at night, circa 2000. (Photo source: U.S. National Aeronautics and Space Admin istration [NASA]) Figure 4-Sb. Composite photo of the earth at night, circa 2012. (Photo source: NASA Astronomy Picture of the Day website) 4-6 Obtrusive Light widespread use and the necessity for roadway lighting wavelength (violet, blue, green) content, unless steps systems to be energized d u ring hours of da rkness. are taken to mitigate the problem. As shown in the com posite nighttime satellite photos in Sky glow minimization is described i n more deta il in Figures 4-Sa and 4-Sb, while outdoor electric lighting ANSl/I ES LP-1 1 -20,2 which incl udes a combination of the has improved, it is stil l very prominent throughout the fol lowing strategies: popu lated areas of North America and the world. This lighting contributes to sky glow, increasing nighttime sky • Mini mize u pward em issions • Mini mize non-target lighting • Do not over l ight • Tu rn off or dim outdoor lighting d u ring low or no brightness. As the amount of outdoor lighting increases, the concern for reducing and mitigating sky glow is also growing. (See also Section 4.4.2 Mitigation of Glare.) A sky glow situation is shown in Figure 4-6 where the activity • Minimize short-wavelength light spectral distribution sky brightness over a popu lated area is very evident. 4.5.2 Sky Glow Models. Sky glow models range from a The prevalence of sky glow is attributed to: subjective evaluation (seven-level sky quality scale based Urban and suburban growth with increased on the faintest stars visible to the naked eye in the zenith) exterior lighting to using photometers to map the sky glow intensity in a • Lighting designs that do not control glare and uplight semi-hemispherical cone. (Refer to ANSI/I ES LP-1 1 -202 for ful l • Inappropriate lighting equi pment selection and descriptions of sky glow models.) In addition, the U.S. DOE • insta l lation • Light sou rces with increased short-wavelength spectral d istribution Sky glow is caused by a combination of light emitted upwa rd from l ight sources and from upward-reflected light. Light that is d i rected u pward (whether by reflection or from the l u m i naire itself) is visible from the ground when it reflects off particulate matter in the atmosphere, typically moisture and/or air poll ution. Sky brig htness i ncreases i n proportion to the i nstal led lu mens as well as with l ight sou rces with more short- issued a report on sky glow from streetlights,6 which reviews different sky glow models and recommends the Sky Glow Simulator developed by Miroslav Kocifaj in 2007. Walker's Law7 has been used to estimate sky glow based on the level of population and human activity. With Walker's Law, the increase in lumens to an area can be calculated to determine whether there is an increase in impact on the community. Sky glow can be measured and used to predict the sky q ua l ity index (SQI). An example is shown in Figure 4-7. 4.4.3 Mitigation of Sky Glow. Light emitted directly from the l u m inaire i nto the sky can be reduced by using l u m i na i res with no u pward emitted l ight (a BUG rating of UO; see Section 2.6.1). Luminaires with a BUG rating of U1 m ight also be considered, as they emit very l ittle u pward light. The use of light sou rces with less output in the shorter wavelengths (violet, blue, green) can also reduce sky glow by reducing Rayleigh scatteri ng. I n addition to l i miting u pward light, it is i m portant to u nderstand that minimizing reflected l ight by not over-lighting outdoor areas reduces sky glow as well. Typically, an asphalt road will reflect far less light than a Figure 4-6. Typical sky glow situation. concrete su rface will. 4-7 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Figure 4-7. Example of a sky glow calculator. (I mage courtesy of Clanton & Associates, Inc.) Lig hti ng d esign and l u m i na i re selection play a major of North America will eventua l ly be affected by some role in red ucing sky glow. M itigation measures i nclude: level of obtrusive light bylaw. • • • • • Selecting l u m i naires with minimal to no upl ight (UO or U l ) Many governmental bod ies throughout North America Avoiding over-lighting, thus red ucing t h e reflected have developed l ighting codes or bylaws as a principal l ight contribution means to prevent poor exterior l ighting practices that Selecting l u m i naires appropriate for adjacent encourage or al low excessive obtrusive light. A well­ properties, using lighting zones as a guide written exterior lighting ordinance wi l l provide g uida nce Tu rning off or d i mming lighting when not req uired on designing lighting that minimizes obtrusive light, or during periods of l ow activity including reducing sky glow and l ight trespass. Minimizing short-wavelength spectral d istribution The Model Lighting Ord i na nce (ML0)4 was jointly in the l ight sou rces d eveloped by the I E S a n d I DA . It req u i res that street lig hts be fu l l y sh ielded (defi ned as "no l u m i nous 4.6 Obtrusive-Light Regulations flux above horizontal "), yet exempts street l i g hting It is importa nt to note that groups l i ke the I nternational fro m M LO com plia nce u n less the street l i g hting Dark-Sky option is adopted by the gove r n i ng body. The street Association (I DA) a re championing the red uction of obtrus ive l i g hting through the lig hting option o n ly recommends BUG ratings for the establ ish ment of l oca l ord i nances, as wel l as promoti ng va rious Lighting Zones. Lumen density and control national, state, and provincial sta ndards to red uce cu rfews a re not reg u lated. (Refer to RP-33-1 42 for fu l l o btrusive light. M u ch of this effort is cu rrently taking d escriptions a n d appl ication g u i d e l i n es related t o the place i n the United States, but it is expected that a l l M LO.) 4-8 Obtrusive Light 4.7 Im pacts From Off-Roadway Obtrusive Light 4.7.2 Mitigating the Effects of Obtrusive Light Obtrusive l ight from off-roadway facil ities or lighting From Off-Roadway Sources. To assist with m itigating systems onto the roadway system can compromise obtrusive l ight on roadways from off-roadway sources motorists' vision through i ncreased veiling l u m inance the fol l owing approaches are recommended: and glare, thus red ucing their ability to perform visual • All outdoor lighting designs should be undertaken by qualified lighting professionals knowledgeable tasks. about controlling obtrusive light. Spi l l l ight levels 4.7.1 Some Cond itions Wherein Obtrusive Light on the roadway from off-roadway sources should Might Be Created for Road Users. The following not exceed those noted i n Table 4-2 (Section off-roadway cond itions have the greatest impact on 4.3.1). roadway users: • • lighting is covered in detail in Chapter 1 9. Brig ht, consensus docu ment for communities to use. (Refer aima ble, porta ble l ights for temporary work zones to ANSl/IES LP-1 1 -203 for detailed i nformation on are often placed very close to the veh icle path and the MLO use and adoption guideli nes.) have the potential to visua l ly impair roadway users • Lig hti ng zone adjacencies to roadways should be through glare and spi l l l ight. determined and used in determ ining BUG ratings To avoid negative im pacts from temporary work and other design criteria. zone lighting, agencies i n charge of roadways should develop and enforce the • Luminaires with appropriate mounting heights and preferred with low-G BUG ratings should be used for off­ placement of such lig hts within the work zone. roadway facilities whenever possible, to red uce In general, the recom mendations of Chapter 1 9 im pacts on the roadways. should b e fol l owed a n d l u m inaires oriented s o that • Com munities should adopt a l ighting ordina nce that limits obtrusive light. The IES/IDA M L04 is a Temporary work zone lighting. This type of • The l ighting design for i ntensely lighted faci l ities they do not adversely affect road users or nearby using aimable fixtu res, such as sports facil ities and properties. parks, should include analyses for glare and spi l l l ight Area lighting. Intensely lighted areas that may onto roadways. Such designs should be reviewed adversely affect roadway users include storage by representatives or staff of roadway owners who areas, cargo termina ls, sports fields, warehouses, are q ual ified to evaluate designs for obtrusive l ight auto sales l ots, fast food outlets, conven ience im pacts. It is im portant for municipa l ities to control stores, fi l l ing stations, and others. Owners with and l i m it glare and l ight trespass onto the rig ht of retail establishments often l ight their facil ities far way from sou rces near the right of way. beyond recom mended minimums as an attempt to attract attention and customers. • Roadway owners should seek the a uthority to enforce the correction of lighting insta l lations that Issues with area lighting can ra nge from visibil ity reduce visibility or the abil ity to perform d riving problems related visual tasks. caused by eye adaptation when tra nsitioning from a brig htly lighted area (e.g., a • filling station canopy area) to a more d i m ly lig hted roadway, to glare obscuring the d river's vision, to costly. To reduce impacts, it is recommended that the an increase in visual c lutter creating confusion or above recommendations be implemented and enforced eye fatigue. as part of the d esign of these facilities and systems. M itigating impacts after the system is i nstal led might be Advertising signs. Advertising signs may be a source of visual c l utter a n d g lare, especially if the signs are d i rected at del ivering messages to 4.8 Lighting I mpacts on Species and Habitat roadway traffic. Minimizing maximum l u minance Obj ections to exterior lighting of any kind, including will reduce glare. Changing copy and motion should roadway l ighting, often include stated concerns for be avoided to minimize d istraction. animal (incl uding i nsect) species, as wel l as plant and 4-9 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities animal habitats. A recent study in l l linois8 found that In particular, the fol l owing conditions should be avoided plant g rowth near hig hways was negatively affected by when l ig hting is to be i nstalled for hig hways, roadways, the roadway l ig hting. or other pu rposes near an airport: • Viewed from the air, streetlig hts making a pattern Lig hting ordinances for sensitive areas are i ncreasingly similar to an approach, runway l ighting system, requ iring wildl ife-friendly lighting. The body of research or obstruction, as this would create a hazard due in this topic is g rowing. (Refer to ANSl/IES LP-1 1 -202 for to the appearance as seen from the air within the additional information.) fl ight paths a round a n aerodrome. For example, where a road l ies near a n aerodrome that has aeronautical ground l ighting and the road has a 4.9 Potential Health I m pacts of Lighting on similar a l i g n ment to the ru nway, the road l ighting H u mans can present a pattern to the p i l ot that is s i m i l a r to The effect of exposure to l i g ht at night on human hea lth the ru nway lighting. is a n area of ongoing research. Studies i n the fields of • Light intensity, whether steady or flashing, which biology and medicine have identified l i n ks, in both cou ld cause g l a re i n the d i rection of a n aircraft the la boratory and the field, between l ig ht exposure approaching as wel l as d uring taxiing to its final at night and a variety of h u m a n health risks. Ma lad ies position on a n aircraft stand. under investigation include sleep d isorders, depression, seasonal affective disorder, and some forms of cancer. • effectiveness of the approach and runway lighting, Some of the research involves exposure to relatively particu larly d u ring periods of reduced and/or l ow high levels of l ig ht at night, such as one m ig ht receive visibil ity. in sh ift work. The World Health Organ ization (WHO) now categorizes l ig ht exposure of this sort as a g roup • a false signal to a pilot. Other researchers9 have i nvestigated health effects levels that m ig ht be associated with l ig ht trespass i nto a The color of the l ig ht being such as to cause it to be mistaken for an aeronautical g round light or to give 2A carcinogen (the same category as cigarette smoke). from l ower level l ig ht exposure (1 lux or less), including The overa l l a mo unt of i l l u m i nation d i m i n ishing the • The aerona utica l g round l i g hts being obscured from the pilot's view. sleeping area from outdoor lighting. (Refer to I ES TM-1 81 810 for a ful l discussion, including research references, Another critical function in an airport is at the control on the im pacts of l ig ht at night for h u ma ns.) tower. Although this is at a fixed position, the personnel in the tower need to manage incoming and outgoing flights and a i rcraft movement on the apron. It is critical 4.1 0 Impacts of Exterior Lighting on Airports that no u pl ig ht reach the tower cab. Light intensity Ai rcraft pilots rely on a specific pattern of the aeronautical should not create g low or glare that could affect the g round lig hts d u ring the daytime at reduced a nd/or low activities of a tower controller. visi bility periods and at nighttime. These a re principa l ly the approach l i g hts and ru nway l i g hts whose purpose is Any tempora ry work a n d acco m pa nying l i g hting to assist the pilot in aligning the aircraft with the ru nway installation sha l l not impact the airport's flight control and with touchdown at the correct point. Other lights activities. (red or clear flashing) are used to marked obstructions in the vicinity of the aerodrome.* Therefore, l i g hts should The designer should refer to an airport diagram to not be displayed that could confuse or distract pilots by locate the facility or, better, coordinate with the civil being m istaken for aeronautical g round l ights. aviation authority. (Note: Information on airport l ig hting can be found in ANSl/IES RP-37-20.11) · aerodrome - A defined area on land or water (including any buildings, installations and eq u i pment) intended to be used either wholly or in part for the arrival, departure and surface movement of a ircraft. (ref. ICAO - AN N EX 1 4 - 201 5 version). 4-10 Obtrusive Light R E F E R E N C E S FOR CHAPTER 4 1. I l l u m i nating Engineering Society. ANSl/IES LS-1 -21 , Lighting Science: Nomenclature and Definitions for I l l u m i nating Engineeri ng. New York: I ES; 2021 . Onl ine: https://www.ies.org/standards/definitions/. (Accessed 2021 J u l 29). 2. I l l u m i nating Engineering Society. ANSl/IES LP-1 1 -20, Lighting Practice: Envi ron m ental Considerations for Outdoor Lighti ng. New York: I ES; 2020. 3. I l l u m i nating Engineering Society. ANSl/IES LP-1 0-20, Lighting Practice: Susta inable Lighting - An Introduction to the Environmental I m pacts of Lighting. New York: I ES; 2020. 4. International Dark-Sky Association (IDA) and I l l u m inating Engineering Society. Joint I DA-IES Model Lighting Ordinance (M LO) with User's G u ide. New York: I ll u m i nating Engi neering Society; 201 1 . Onl ine: https://store.ies. org/prod uct/ida-ies-mlo-1 1 -model-lighting-ord i na nce-mlo-with-users-gu ide/. (Accessed 2021 Jul 29). 5. I l l u m i nating Engineering Society. ANSI/I ES TM-37-21 , Techn ica l Memorandum: Description, Measurement, and Esti mation of Sky Glow. New York: I ES; 2021 . 6. An I nvestigation of LED Street Lighting's I m pact on Sky Glow. Washi ngton, DC: U.S. Department of Energy (DOE); 201 7. On Ii ne: https://energy.gov/sites/prod/files/201 7/05/f34/201 7_led-i mpact-sky-glow.pdf. (Accessed 2021 J u l 29). 7. Walker M. The effects of u rban brightening on the brightness of the night sky. San Francisco: Astronomica l Society o f the Pacific; 1 977. 8. Palmer M, G i bbons R , Bhagavath ula R , Holshouser D . Roadway Lighting's I m pact on Altering Soybean Growth, Vol. 1, 1 7-014. U rbana, I l l .: I ll i nois Center for Transportation, U niv of I l l i nois at U rbana-Cha mpaign; 201 7. (FHWA ICT-1 7-01 0). 9. Lucas RJ, Peirson S, Berson DM, Brown TM, Cooper HM, Czeisler CA, Figueira MG, Gamlin PD, Lockley SW, O'Hagan J B, et al. Measu ring and using light in the melanopsin age. Trends N e u rosci. 201 4;37(1 ):1 -9. Pu blished online 201 3 Nov 25. DOI: 1 0.1 01 6/j,tins.201 3.1 0.004. 1 0. I l l u m i nating Engineering Society. IES TM-1 8-1 8, Light and H u ma n Hea lth: An Overview of the I m pact of Optical Radiation on Visual, Circadian, N e u roendocri ne, and N e u robehaviora l Responses. New York: I ES; 201 8. 1 1 . I l l u m i nating Engineering Society. ANSl/IES RP-37-20, Recommended Practice: Lighting Airport Outdoor Environments. New York: I ES; 2020. 4-1 1 The Pla n n i ng a n d Design Process Cha pter 5 CO N T E N TS 5.1 5.2 5.3 5.4 Typical Situations That May Require Lighting Design . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 5.4.7 Prepare Pla ns, Specifications, and Estimates (PS&E) . . . . . . . . . . . . . . . 5-1 7 Design Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2 5 .4.7.1 Plans . . . . . . . . . . . . . . . . . . . . . . . . 5 - 1 7 5.2 . 1 Safety. . . . . . . . . . . . . 5-2 5.4.7.2 Specifications . . . . . . . . . . . . . . . 5 - 1 7 5-3 5.4.7.3 L u m i naire Performance . . . . . . . . . . . . . . . . . . 5.2.2 Cost 5.2.3 Optimization of Lighting 5.2.4 Aesthetics . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4 5.4.7.4 Es ti mates . . . . . . . . . . . . . . . . . . . 5- 1 8 5.2.5 Environmental Considerations . . . . . . . 5-4 5.4.7.5 Contract Doc u m ents . . . . . . . . 5 - 1 8 5.2.6 Site Conditions . . . . . . . . . . . . . . . . . . . . . . 5-4 5 .4. 7.6 Owner Review . . . . . . . . . . . . . . 5 - 1 8 5.4.7.7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3 Document . . . . . . . . . . . . . . . . . . 5 - 1 7 5.2.7 Col l ision Data and I nvestigations . . . . 5-6 5.2.8 Adaptive Lig hting . . . . . . . . . . . . . . . . . . . 5-6 5.2.9 Prioritizi ng . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6 5.4.8 Bid o r Tender . . . . . . . . . . . . . . . . . . . . . . . 5-1 8 Lighting Master Plans . . . . . . . . . . . . . . . . . . . . . 5-7 The Design Process . . . . . . . . . . . . . . . . . . . . . . . .5-9 5.4.9 Construction . . . . . . . . . . . . . . . . . . . . . . . 5-1 9 5.4. 1 0 Post-construction: Drawings . . . . . . . . 5-1 9 5.4.1 Perform Pre-design . . . . . . . . . . . . . . . . 5-1 0 5.4. 1 1 5.4.2 I nvestigate Site Conditions . . . . . . . . . 5-1 1 5.4.3 Defi ne Lighting Design Criteria . . . . . 5-1 2 5.4.4 5.4.6 Post-construction: I ntegration and Commissioning 5.5 Perform Lig hting Design . . . . . . . . . . . 5-1 3 5.5.1 Capital Cost 5.5.2 Operating Costs . . . . . . . 5- 1 4 5.5.3 Life Cycle Cost Perform Electrical Design . . . . . . . . . . . 5-1 5 5.5.4 Life-Cycle Cost Desig n i n g H i g h-Mast . . . . . . . . 5 .4.5 . 1 Electrical Design Elements . . . 5- 1 5 5.4.5.2 E l ectrical Calcu lati o n s . . . . . . . 5 - 1 6 Perform Geotech nical and . . ... . . . . . . . . . . . 5-20 Calculating Costs . . . . . . . . . . . . . . . . . . . . . . . . 5-20 5.4.4.1 Lighting . . . . . 5.4.5 Qual ity Control (QC) for PS&E . . . . . . . . . . . . . . . . . . . . . 5- 1 8 . . . . . . . . . . ... . . . . . . . . . . . 5-20 . . . . . . . . . . . . . . . . . . . 5-20 . . . . . . . . . . . . . . . . . . . . 5-2 1 . . Calculation Example . . . . . . . . . . . . . . 5-21 . 5.6 Verification of Lighting Levels . . . . . . . . . . . . 5-21 5.6.1 Verification by Calculation . . . . . . . . . . 5-2 1 Structural Design . . . . . . . . . . . . . . . . . . 5-1 6 5.6.2 Field Verification 5.4.6 . 1 Geotec h n ical E n g i neering . . . 5 - 1 6 5.6.3 Electrical System Verifications . . . . . . 5-24 5.4.6.2 Structural Eng i neering . . . . . . 5 - 1 6 5.6.4 5.4.6.3 Pole Attachme nts . . . . . . . . . . . 5 - 1 7 . . . . . . . . . . . . . . . . . . . 5-2 1 Field Verification of Lighting Performance . . . . . . . . . . . . . . 5-24 References for Chapter 5 . . . . . . . . . . . . . . . . . . . . . . . 5-25 Chapte r 5 The Pla n n i ng a n d Design Process T his chapter describes the general planning and design process for the roadway lighting systems considered i n this Recommended Practice and is i ntended t o summarize t h e general order and steps req u i red t o successful ly in itiate and complete a design. The processes related to the design of specific types of • roadway lighting systems are contai ned in the i ndividual cha pters in Part 2 - Land development, including new roadways. New roads a re developed that may req u ire roadway Design. l i g hting based on warrants, or the roadway lighting may be specifically requested by the owner or road Designing an appropriate roadway l ig hting system authority. Roadway lighting is typica l l y insta lled involves the systematic consideration and integration of as part of roadway construction, with the l ighting many elements. While the exact process and requirements becoming operational when the roadway opens may vary from agency to agency and even project to to traffic. Because new roads and areas may be project, certain general elements and considerations desig ned and insta l led i n phases to meet budget are common to a l l designs. Because some decisions in or g rowth considerations, lighting designs should roadway lighting design need to be made on a critical be compati ble with previous phases and adjacent path, the order of consideration can a lso be genera l ized. areas whenever possible. Therefore, this chapter describes com mon considerations and presents them as a logical, simplified process. • include roadway lighting as part of a reconstruction The design process described in this chapter may be project on adopted, expanded or refined to meet specific needs. road undergoing u p g rades or or left turn l ane) or major (e.g., fu l l road wideni ng), and is not intended to su persede the existing processes in which l ig hting did not exist. In circu mstances adopted by an agency or organization. where lighting a l ready exists, and the geometric modifications do not affect the physical locations of Though q ua lity control (QC) and q u a l ity assurance (QA) the roadway lighting equ ipment, the designer shall are to be encouraged, these subjects are not covered in determine whether the existing l i g hting system can this Recommended Practice. remain and sti l l meet the cu rrent recommended l i g hting design criteria on the reconfigured road. The ava i l a b i l ity of rel i a b l e a n d accu rate l i g hting When the proposed geometric design mod ifications calcu lation software as a design tool a l l ows designers do affect the existing lighting, a new roadway to optimize the design of roadway lighting systems. l i g hting system should be recommended that w i l l Software, however, has not taken the complexity out of meet cu rrent recommended l i g hting design criteria the roadway lighting design process. Lighting designers for the proposed new geometric configuration. shou l d design the l i g hting system to be properly undertaken by professionals i n other design disciplines. a improvements, whether minor (e.g., additional right The process is meant to provide genera l u nderstanding, integrated with other project elements that may be Upgrades to existing roadways with geometric modifications. The road authority may choose to • Upgrades to existing roadways without geometric modifications. The road authority may choose to u pg rade an u n l it roadway that is not undergoing geometric changes, to improve 5.1 Typical Situations That May Requ i re public safety. Roadway l ighting warrants should Lighting Design be completed to determ ine whether lighting is Lighting systems requ iring design are typica lly installed recom men ded, in the following situations: behavior information and collision data ava ilable. i ncorporati ng cu rrent d r iver 5-1 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities • Retrofits to an existing roadway l ig hting A l ighting system can a lso be retrofitted to reduce system. An existing roadway l ighting system may spill light i m pacts and improve visib i l ity for roadway be improved throug h a retrofit even when there is users. These retrofits typical ly involve replacing no change to the physical portion of the roadway. luminaires that have l ittle or no optical control The most common retrofit scenario i nvolves the with one or more types that a re desig ned to limit removal of existing l u minaires and installation of upl i g ht and glare. An improved distribution of the new l u m i naires with a d ifferent l ig ht source in l ight onto the roadway can someti mes result in less order to improve lighting, reduce obtrusive light energy req u i red for the system. i m pacts, a nd/or red uce power con s u m ption. Lighting systems can also be retrofitted if they a re Road authorities may wish to undertake wide­ not operating as i ntended due to age or d isrepair. It ranging retrofit programs with improved l u m inaire is i mportant to note that no l ig hting system w i l l last l ig ht sou rces and optics where the retrofit makes forever. If q u a l ity equ ipment is i nsta l l ed and proper economic sense. Retrofits may a lso be undertaken m a i ntenance is undertaken, a l i g hting system if the existing roadway l ig hting system has reached will typical ly be replaced with new technology, the end of its useful life. or as a result of redevelopment, prior to the end of its operating l ife of 20 to 30 years. I ndividual If the pu rpose is a red uction i n energy, a retrofit of luminaires that fail are usually replaced as part of a n existing system with a new lighting technology should routine mai ntenance. be considered if the payback period makes it cost effective and fu nds for the retrofit are ava i lable. In the 1 980s and 1 990s, many cities 5.2 Design Issues found a favora ble cost-benefit ratio in switching A roadway l i g hting system i nvolves the systematic from mercury va por (MV) to more energy-efficient consideration of a n u m ber of practical aspects, including: high pres s u re sod i u m (H PS) l i g ht sou rces, and • Safety • Insta l lation cost • Optim ization of l ig hting • Aesthetics • Environmental considerations level s and determi ned that l ower l i g ht l evels, • Site conditions provided by lower wattage l u m inaires, could result • Collision data and i nvestigations • Operating costs • Maintenance costs consequently retrofitted their streetlights. Higher efficiency sources conti nue to be developed, offering reduced operating costs. Some cities have also eval uated existing lighting i n reduced power costs. Dimming systems and light emitting diodes (LEDs) (Chapter 6, Section 6.3.1 and Section 6.5.2) offer the potential for economic benefit via a retrofit to a n existing l i g hting system . 5.2.1 Safety. The primary objective of roadway lighting is to enhance road user safety by providing road A n existing l ig hting system may a lso b e retrofitted users with im proved nighttime visibi l ity of roadway as part of revita l ization of an esta blished a rea. cond itions and potential hazards. (Refer to Section 1 .3 I m p roved l ighting levels and aesthetics of new l i g hting eq u i p ment can make a n area more inviti ng, - The Value of Lighting for further reasons to provide roadway lighting.) which can i n turn stimu late economic growth. 5-2 However, it might be difficult to assign a n economic Light poles and other physical devices (such as electrical va lue to retrofitting a commercial a rea. Lighting is transformers and one of many factors that can contribute to economic potential hazards to errant veh icles and should be g rowth in a given a rea. installed in safe locations. The designer of the roadway power su pply cabi nets) present The Planning and Design Process l ighting system should a lso consider the location of Life cycle cost is also a very im portant consideration. Life pol es, l u m inaires, and other electrical equipment that cycle costs include capital costs as well as operating form the roadway l ighting system, in order to permit costs over the life of the system (typica l ly 20 to 30 m a i ntena nce crews to cond u ct activities i n a safe, years). Comparing l ife cycle costs is a n efficient way to economica l a n d effective man ner. Clear zones and com pare the val u e of different l i g hting systems. While req u i rements for pole locations a re further explai ned i n project proponents with fixed amounts of fu nding for constructing a roadway l ighting system may focus on Section 6.9.3 - Clear Zone Requirements. the capital costs, l ife cycle costs can vary sign ificantly As discussed in Chapter 2 - Vision and Fundamental based on design variables, and operating costs may Concepts, a lthoug h roadway l i g hting may i m p rove exceed the capita l cost of a roadway l i g hting system the visibil ity of objects at night, there is a potential for over its i ntended l ife. conditions where a d river's vision needs to adapt to darkness or lower levels of l u m inance when leavi ng the l ig hted area . Lig hting a lso has the potential to create g lare, which may reduce or i n hibit an i nd ividual's ability to perform the visual tasks associated with use of the roadway. For these reasons, specific lighting design criteria have been developed as defined and explai ned in the various chapters of Part 2 - Design. Different l ig hting systems will have different life cycle costs. Owners may wish to consider a cost-benefit ana lysis if d ifferent systems can be used to l ig ht a roadway. An exa m p l e of a scenario req u i ring a cost­ benefit ana lysis wou l d be compa ring a h i g h-mast l ighting system for a n interchange to a conventional (davit-style) lighting system. New lighting technolog ies may also warrant a cost-benefit analysis to justify their 5.2.2 Cost. The cost of a roadway lighting system is composed of two major considerations-capital cost a n d operating cost. use. Cost-benefit ana lyses should include both capital and operating costs. Procedu res for ca lculati ng the various cost elements are Capital cost (sometimes known as construction cost) is often viewed as the main issue for a roadway lighting project. Because the capital costs for a roadway lighting system are significant, budget considerations should be d iscussed with the road authority prior to proceed ing with the desig n . fu rther described in Section 5.5 - Calculating Costs. 5.2.3 Optimization of Lighting. In general, a roadway section req uiring l i g hting should be desig ned to use the least a mount of l ig hting infrastructure possi ble to provide the recom mended a mount of light for roadway user safety. By evaluating the photometric reports of Operating costs are an often-overlooked component of a project because ma intena nce and operations va rious products and selecting luminaires with optics most suitable for a g iven appl ication, l i g hting designers can optimize the design and use the fewest n u mber budgets a re typically sepa rate and d istinct from of l u minaires and poles, red ucing both capital and l ife construction budgets. As new l i g hting is added to cycle costs. existing infrastructu re, overal l operational costs w i l l rise. The use of fewer poles also i m p roves the roadway O pe rating cost calcu lations s h o u l d include both aesthetics and reduces visual clutter, potentially a l so ma intena nce (largely lamp (and/or ba l last or driver red u cing the level of confusion for a road user. Most or power supply) replacement, as a pplica ble, and important, the use of fewer poles enha nces safety by associated cleaning of l u m inaires) and energy costs. red ucing the possibi l ity of col l isions with poles by errant Energy costs will account for a sizeable portion of the veh icles. l ife cycle cost for a proposed project. Because energy costs typically trend u pwards over time, energy efficient The operation of a l i g hting system may be optim ized design is a n i m portant aspect of roadway l i g hting using adva nced l i g hting controls, as discussed i n design. Section 6.1 0 - Roadway Lighting Control Systems. 5-3 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities In addition, such systems may benefit from integration • Vehicle-wildlife conflict areas. In rura l areas into a road authority's i ntel l igent transportation system with a significant concern or a h istory of wild l ife (ITS). conflicts with motor vehicles, consideration should 5.2.4 Aesthetics. The aesthetics of roadway lighting This wi l l assist roadway users i n identifying wildl ife be g iven to l i g hting a reas past the roadway edge. is most heavily i nfl uenced by the pole height and entering the roadway or adjacent areas, and may layout. Lighting designers a re enco u raged to i nitiate aid road users in avoid ing collisions with animals. their desig ns with the critical pole placements in the I l l u m i nation of areas past the roadway edge is typical layouts described i n the various chapters of Part particu larly beneficial on highways with m i n i ma l 2 - Design. rig ht-of-way tree clearing. T h e u s e o f approved taller poles with a larger setback from the roadway For u rban conditions, roadside development should will facil itate a wider lig hted area. be considered when selecting m o u nting heights to m itigate l i g ht trespass onto adjacent properties and to • l i g ht i n g l ig ht im pacts, particu larly in u rban areas, including adjacent structu res. high Roadway systems s h o u l d b e designed t o m i n i m ize obtrusive minimize or e l i m i nate poles that are out of scale with I n a reas with Obtrusive light im pacts. l ight trespass, sky g l ow, and offsite glare. (Refer to Chapter 4 Obtrusive Light for more i nformation.) pedestrian vol u mes, such as downtown a reas, the use of l i g hting system s with shorter poles may be su itable for a more pedestrian­ Add itional information on environmental considerations can be found i n ANSI/JES LP- 7 7 -20, Lighting Practice: scale appearance. Environmental Considerations for Outdoor Lighting.1 Special aesthetic req uirements may be desired (or even req u i red) in some u rba n or themed environments. 5.2.6 Site Conditions. The following site conditions These should be considered in the lighting design process: a reas include city centers, c o m m e rcial developments, and recreational districts. Unique urban • The presence of trees and bushes. Where design req uirements will typical ly necessitate the use of trees and bushes are proposed within the road decorative poles and l u m i naires to suit the architectural a l l owance, the l ig hting designer should work with theme for the a rea. The desig ner is cautioned that the la ndscape designer to find the best locations decorative poles and l u mi n a i res, as wel l as special for trees and bushes with respect to the l u minaires. fin ishes, can add significant costs to a project, both from In all cases, the lighting should take precedence capital cost and maintena nce perspectives. However, over the i nsta l lation and mai ntenance of trees the use of decorative l u m i naires with wel l -desig ned and bushes. The spacing from the center of trees optics can someti mes be less expensive than em ployi ng to poles should take into account the mature tree separate systems for performance and aesthetics. canopy height and width. The designer should determine where trees and bushes wil l interfere Where possible, light pole heig ht, l u m inaire wattage, with lighting. If the trees and bushes interfere with a n d l u m inaire and pole types should be designed and the lighting of a n adjacent wal kway para l lel to the specified to match or complement street furniture such roadway but do not affect the roadway lighting, as benches, awnings, canopies, and pla nters. 5.2.5 Environmental Considerations. Some hig hway separate walkway lighting should be considered. • Severe weather conditions. Areas prone to e nvironmental frequent severe weather conditions (e.g., severe concerns related directly to lighting. Designers should fog, snow, ra in, l i g htning) may req u i re special consider how to m itigate the negative effects of design considerations. While there are no exact roadway l ig hting when desig ning for these situations. methods for dealing with these conditions, some Special situations include: suggestions include the fol l owing: and 5-4 street l ocations pose special The Planning and Design Process ° Fog. Areas with frequent occurrences of thick, electrical e q u i pment, and poles that a re installed dense fog may warrant a lower mounting height near salt water should be designed to withstand in order for the lighting to aid in guidance for the this type of atmosphere. Concrete, a l u m i nu m, or driver. With respect to fog, no l ig ht source is better ga lvan ized steel poles may be a n effective way than another. The idea that long-wavelength to red u ce problems associated with corrosion. sources such as sod i u m a re better, popularized by Aluminum or composite materials should also be French research from the 1 950s, has not proven to considered for l u m i naires. be true. Fog particles are nearly 1 0 times too large to benefit from long-wavelength penetration. 0 • Shadows. Shadows a re created by structu res or other obstacles that block l ig ht from reaching its Snow. Reg u l a r high snow accu m u lations may intended target. As a general rule, the closer the affect lighting systems due to snow load ing on obstructions to the l u m inaire and the more intense the poles and bases. The pressu res from excessive the l ig ht sou rce, the harsher the shadow. Typical snow accu mulations on light poles have been scenarios that create shadows include underpasses known to snap breakaway bases, and may create and overpasses, plantings, retaining wal ls, median a fa l l i n g hazard a nd/or traffic obstructions when barriers, signs, and buildings. A designer should the snow melts. Pole bases may also be displaced be aware of shadowing, as it will have a negative by frost heaving, res u lting in poles being out of impact on visibi l ity. Most lighting design software p l u m b and wiring connections being stra i ned can consider obstructions and assess their i m pacts or broken. Access to wiring in pole hand-holes on the lighting. Shadows can usua lly be avoided or junctions boxes may also be restricted due to thro u g h proper l u m i na i re place ment. Where they snow cover. Lighting equi pment, especia lly poles, can not be avoided, additional l u m i naires should will be subject to corrosion in a reas where roads be added i n appropriate locations to reduce the a re sa lted and sanded throughout the winter. negative effects. Use of corrosion resistant materia l s such as concrete, a l u m i n u m, and galva n ized steel along with reg u l a r cleaning w i l l reduce the effects of corrosion. 0 Shadows are not l i m ited to the hours of darkness. In fact, daylight may pose a problem with a reas that a re blocked from sunlight. These areas may Lightning strikes. Lighting systems insta l led in req u i re addition l i g hting to reduce the i m pacts of a reas experiencing a large num ber of l ightning shadows. This is especia lly true with underpasses stri kes may n eed additional g ro u n d i n g and and tunnels, as shown in Figure 5-1 . lightning suppression devices at the main service. 0 • High rainfall. Water accu m u lation from heavy Assessing the i m pacts of shadows i s a complex issue. rainfa l l Eye adaptation is a key factor when transitioning on road su rfaces can red uce road user visibility due to g la re. Simply i ncreasing between lighting levels can cause additional g l a re, which i l l u m i nation will further red uce visibility. The use of retro­ 2.2.5 Adaptation. There is no exact form u la reflective pavement ma rkings designed for a wet for determ i n i n g where supplementa ry l i g hting road surface (see Section 1 .6) may be a good is required to overcome shadowing. I n g eneral, complement to a lighting system to improve the designer should identify and include a ny a reas of l evels, s i g n ificant as d ifferences described in in Section d river g u ida nce in these a reas. The use of obstructions in the lighting software calcu lations. l u m i naires with cutoff or fu l l-cutoff optics should Computer rendering software can also be used to be considered to reduce vei l i n g l u m i nance where simu late the effects of shadows, as shown in Figure high rainfa l l is a common occurrence. 5-1 . The fig u re shows the expected shadowing on Coastal areas. Areas in close proxi m ity to bodies the right, with a photo of the actual situation on the of salt water may experience chem ical corrosion of left. Simulations of nig httime conditions can a lso be roadway lighting system components. Lu minaires, developed. 5-5 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Figure 5-1 . Calculated effects of shadowing (right) compared with actual effects (left). (Photo and rendering courtesy of WSP) 5.2.7 Collision Data and I nvestigations. Because warra nting decisions a re based i n part on col lision data, More-deta i led i nformation on adaptive l ig hting systems may be found in Chapter 6, Section 6.1 0. it is critical that specific col l ision data related to lighting systems be maintained by the road a uthorities. The 5.2.9 Prioritizing. m i n i m u m data col lected should include the location, refu rbished roadway lighting system should be based Priorities for i nstalling a new or type of coll ision (e.g., rear-end, side i m pact), date, time on a "val u e for dol lar" a pproach. For a refu rbished of day, whether it was light or da rk, direction of travel for l ighting system, it is i m portant to keep i n mind that any a l l veh icles, and weather conditions. electrical system will deteriorate over time to the point that it will require upgrading or replacement to maintain Col l ision investigators, injured parties and insurance safe operation. A l i g hting system that fails to operate as carriers may desire to review lighting levels for a location designed and req u i res freq uent or ongoing repair is a where a col lision occurred and determ ine whether they prime candidate for refu rbishment or retrofitting. When are in accordance with recommendations or standard retrofitting due to u n reliable operation, mai ntenance practice. Col l ision i nvestigators may also be interested personnel sho u ld be consulted to identify the causes in the lighting l evels recorded with an i l l u m inance meter for the u nreliable operation so that new systems can be in accordance with the lighting design grid spacing improved. noted in the appl icable cha pters in Part 2 - Design, and/ or the level and frequency of mai ntenance activities. New technologies may also be a basis for upgrade. When assessing a new technology the designer should 5.2.8 Adaptive Lighting. Adaptive lighting involves assess the payback period for the retrofit. Payback is varying lighting levels to suit activity levels during off-peak typica l ly based on energy cost savi ngs compared to periods. This can result in energy savings and reduction in the cost of the retrofit. Other considerations include operating costs. Adaptive lighting is achieved via the use mai ntenance savings, improved safety, and increased of lighting controls that a llow l u mi naires to be d i m med reliabil ity. or tu rned off at pre-defined times. In areas where activity levels vary, occupancy based control systems may be New i nsta l lations of roadway l i g hting a re typically considered. Adaptive lighting systems may be appl ied prioritized through warra nting. If l ig hting is warranted in u rban or rura l settings, but they typically provide the and budgeted funding is not avai l a b l e, then the l ig hting greatest benefit when applied to continuous lighting should be prioritized based on the l ist below, as well as systems in urban areas. the estimated cost of the i nstallation. One of the key 5-6 The Planning and Design Process criteria should be nig ht-to-day collision ratios. Areas public i mage and economic development goals, and with the hig hest ratios should be given higher priority. technological advancements. A ranked l ist of typical lighting scenarios follows. 1 . Urban areas where pedestrians cross the roadway Lighting master plans define the purpose of the l ig hting (intersections and crosswalks). The highest priority a n d conta i n area maps with road types, classifications, sho u l d be g iven to a reas with the hig hest rate of (or l a n d use, pedestrian and cycl ist routes, parks, and potential for) pedestrian-vehicle or cyclist-vehicle oth e r i nfrastructure information. They also contai n collisions. Areas with l i m ited sight d istance should i nformation regard i n g l u m i na ires and poles, l i g ht also be given high priority. sou rces, l i g hting l evels, design criteria, design a n d 2. Urban non-gated railway crossings. The higher the construction specifications, historica l considerations, traffic vol u m e, train vol ume, and collision rate, the and recom m endations. They are com bined i n a single higher the priority. package that becomes the basis for l ig hting projects. An 3. Roundabouts. Lighting is im portant due to lack of assistance from car head l a m ps. The higher the traffic vol u m e and collision rate, the higher the priority. (Note: The FHWA Hand book, Section 2.6, reco m mends i l l u m i nation for all rou nda bouts.2) 4. Urban areas of demonstrated conflicts. The higher the traffic vol u m e and col l ision rate, the higher the priority. 5. Urban intersections. The higher the traffic vol u m e and col l ision rate, t h e h i g h e r the priority. exa mple of selected content from a l i g hting master plan is shown i n Figure 5-2. The benefits of such plans include the coordi nation of the various m u n icipal l i g hting functions, proactively planning l i g hting for the different areas of a com m u n ity by recog nizing their u n i q u e character and needs. The plans a lso provide sched u ling of capital expenditures, as well as implementation and maintenance strateg ies. Lighting master p lans are based on the concept that p u b l i c facilities should e n ha nce safety, e ncourage 6. Urban roadways with sidewalks. The h i g h e r the economics, contribute to beautification, and provide a traffic vol u m e, pedestrian vol u me, and col l ision sec u re environment for people and property. In these rate, the higher the priority. contexts, transportation related l ighting is viewed as a 7. Freeways and highway interchanges. The g reater the key component of com m u n ity management. traffic vol u m e and nightti me col l ision rate, and the c l oser the spacing of interchanges, the higher the Lighting master plans are typica l ly adopted by a priority. j u risd iction by bylaw, resolution, or similar measure. As 8. Rural areas in similar order to urban areas noted such, they may dictate specific design requirements for above. The higher the traffic vol u m e and col lision roadway l ighting. The pu rpose of a l i g hting master plan rate, the higher the priority. is to ensure that adeq uate l ig hting is provided for future development, and that public l ig hting will be installed There is no exact formula for assig ning priority to in a consistent manner that ta kes into account the needs lighting in one l ocation over another if l i g hting is and desires of the citizens. equally warranted for two a reas and budget is o n ly If a n area is desig nated for h istoric preservation, the available for one. l ig hting master plan may define l u m i naires and l ig ht sou rces that a re compatible with and preserve h istorical cha racter or create an enhanced historical character. 5.3 Lighting Master Plans Lighting master plans are forma l documents created throug h a study and planning process. They are based on input from m u nicipal staff, public officials, lighting professionals, citizens, busi ness owners and others. Lighting master plans take into account anticipated eco n o m i c and cu l t u ra l chang es, a com m u n ity's Lighting master plans typica lly address the following major subject areas: • I mproved safety and secu rity provided by l i g hting • Costs (capital and operating) • Aesthetics (daytime and nighttime) 5-7 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities • - 0.:ftl;J :nJ '-1$& tTlll ..........,.. ....... .,,. •CM: c-.cta: Ra .... .,._uaa ------·---- "" ----·-- - - - ----·-----···,-·-- - ----··--_ ____ ... __ I :::::::.":... - :r=:=r· r ,.. I .... .... ......... ...... ... ,.. .. It r r I . .. ..... ......... ...... .... ,.. .... .... ..... . ..... . ., _ •._...._ ,.... Utt:Ad Gll • a•d �·-·LMll lla V... .....­ � � .. ,.. f=i"MI> � ---"9 - -..i M.1111 �r• � IUq;l!'WllllMl a �,.._. I .,_ ..., � .. Ofrllb!dlttL .... :z. � �·' - ......, .... - -....--� .... .,.... �-�,-.w. .. ..,. •1 111' 1 t:;flCVtl. C......"* M>*"H .. --- • I ..• - U •-•••• UU ft ._ ,.....,,.... �•-• •u•• • n- h-,.- � f\11* • � .. . � �fill*: '" .... t\rl:!.inidan- m.cr� ll&ltlL.Ql •psm•1:1t1.-itt -o�lfll Mn•ft...­ fll ......, Mn t.ftt -11\ MOOO • � '*JiO!fl*': � lAf 111ftW 'f11 1D."1;W �llllt .-J• 1 .... .� 1 • IMMIJ hdl -"• ... -� .... �:--. ao.11 .. ,.... �'OWl� ..Ufa9Dtlf'f!Wlq:m ldlllh)W.. • •�---· "ta.., _ _ � ,. 1 . .. .... ....... .. .... .. .- ........... .... .. . ...,. . .. .... ._..... Figure 5-2. Typical content of a master lighting plan document. 5-8 The Planning and Design Process Under no circumstances should lighting master plan Lig hting desi g n criteria Environmental issues and constraints, including requ i rements dictate the quantity or q u a l ity of l ig ht for the control of spill l i g ht, glare, and sky g low a roadway facility, since the safety of the roadway user • Energy use (thro u g h control of unit power density) is of para mo u nt i mportance. • Potential for economic development and the • enhancement of nighttim e activities through • • l ig hting 5.4 The Design Process Preservation of areas of darkness, such as a reas The desi g n process described below is intended to g ive near observatories an o utline of the typical steps undertaken in the design Maintenance requirements of roadway l i g hting. Owners or agencies may have specific req uirements that vary from this process, with Desig ners should check with l ocal officia l s prior to details or req uirements that exceed what is outlined beginning design to determine if a l ighting master in this Recom mended Practice. Figure 5-3 i l l u strates plan is in place or a nticipated. Designers should be the basic project steps and flow. The design process aware of the requirements of l ighting master plans as can be modified to suit the road authority's submission they relate to the specific project u nder consideration. process. Consult Owner Consult Owner Geotechnical and Structural Design (if Required) Prepare Plans, Specifications and Estimates (PS&E) Make Changes as Needed Adjust Variables as Needed Figure 5-3. The design process. 5-9 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities The lighting designer should employ a n internal quality defines the clear zone i n deta i l a n d should be control program (QCP) that is appl ied to the entire referred to prior to undertaking a lighting desi g n . design process. Quality control (QC) processes, part of Road u s e r safety c a n be compromised if clear zone the overall QCP, should involve formal internal checking req u i rements are not maintained. and reviews at va rious stages of the design process. These processes are a i med at i m proving the q u a l ity of Other issues to be d iscussed with the road designer the product prod uced. As the QCP should be specific to include a ntici pated traffic vol umes, road type (e.g., the firm or organization underta king the design, it is not col lector, arterial), a nticipated pedestrian vol u mes, part of the design process shown here. a rea classification (rural or u rban), g eo metric 5.4.1 Perform Pre-design. Prior to starting any design, to the AASHTO G reen Book3 for definition) and l i m itations, and issues such as narrow lanes (refer the roadway l i g hting d esigner shou ld add ress the shoulders and construction staging. It is i m portant following typical pre-desig n considerations: for the l ig hting designer to identify: • Identify applicable standards. A road authority 0 boards, overhead sign structures, and special defined with in their j u risdiction. The standards may pavement markings be comprehensive, or they may only cover specific 0 aspects related to the lighting desig n . These aspects traffic sig nal and lighting structures design req uirements, and construction detai ls. The 0 designer should a cq u ire and ful ly understand the 0 undertaking a desig n. The need for special l ig hting such as temporary lighting, waterway navigation wa rning lighting, Understand roadway geometrics and utilities. and underpass l ighting Roadway geometrics and location of utilities may be obtai ned prior to starting the desi g n . Roadway Dra i nage faci l ities and their i m pact on potential pole locations appl icable sta ndards for the road authority prior to infl uence the roadway l i g hting design and should Signalized intersections and the possibil ity to reduce fixed objects by insta l ling combination may include specific products, design processes, • Advance warning beacons, cha ngea ble message may have esta bl ished roadway l ighting standards • Determ ine architectural or urban design requirements. Architects and u rban designers will l i g hting is typical ly i nsta l led on or adjacent to a often develop concept d rawings that will define roadway, usually within the road a l lowance, and the req u i red look for the poles and l u m inaires in a can conflict with both u nderground and overhead g iven a rea. Colors, shapes, and sizes are i m portant uti l ities. The design of the roadway lighting system a rchitectural and u rba n design considerations. must be coordi nated with the project civil design Lumi naires and poles may req u i re color matching and i nteg rated with all geometric and genera l with a specified standard, or may be req u i red to d e s i g n elements. These elements i nclude, for match street fu rniture such as benches, handra i ls, exa mple, sidewalks, barriers, cu rbs and g utters, and and trash bins. Va ryi ng m ethods for applying retaining walls. Other elements i nclude existing coatings a n d finishes and proposed utilities such sewer, gas, water, and coating) may affect color matching accuracy. Pole underground and overhead communications and finishes are covered further i n Chapter 6 System (e.g., painting, powder power l i nes. Ea rly i nvestigation and coordination Components. The architectural or u rban design will avoid conflicts and costly change orders. The requirements may be defined i n a l ighting master desig ner is enco u raged to consult loca l utility plan document, as described in Section 5.3. agencies to verify underg round utility locations prior to construction. Tree and landscape elements may be im portant architectural features within the road a l l owance. When locating pol es, the clear zone is a very These items need to be coord i nated with the i m portant consideration that w i l l have to be planned light d istri bution i n order to avoid conflicts reviewed with the road designer. Section 6.9.3 and i nterference with the l i g hting. Typical a reas 5-1 0 The Planning and Design Process where coordination with a landscape a rchitect may a i rports and hel icopter landing pads may pose be req u i red include the location of plants and trees problems with defined glide paths and air-traffic that may block l i g hting on the roadway, or tree control operations. Typically, an a i rport a uthority roots that may be in conflict with underground or their governing a uthority (U.S. Federa l Aviation conduits or other electrical equipment. (See also Ad min istration [FAA], Tra nsport Canada [TC], or the Section 3.1 .9 Change in Physical Surroundings.) Mexican Directorate General of Civil Aeronautics [DGAC]) will have specific pole height l i m itations Coordination w i l l a lso be req u i red with other a nd/or optica l req u i rements for the l u m i naires. architectural elements such as benches, planters, Where a l i g hting installation is proposed i n close building canopies and awnings and other street proximity to a n a ircraft landing fac i lity, the facility furniture, as wel l as parking sta l l s and signage. should be contacted so that req u i rements specific I n no i nstance should architectural requirements to that facility can be met. override the l i g hting req u i rements. • Proximity to railroads. Lighting systems near ra ilroad tracks will have specific track-clearance • Perform a condition assessment of existing req u i re m ents. These are noted i n Chapter 1 3 equipment. Where roadway l ig hting and related At-Grade Rai lway Crossings. Poles should b e equipment exist, it may be appropriate to undertake located s o that they d o not conflict with railway an inventory of what exists, as wel l as an assessment gates and a road user's view of the railway's flashing of the condition of the existing equipment. This wil l l i ghts. a l low a designer t o assess what equi pment, if a ny, may be reused. • • Presence of overhead distri bution and transmission lines. Distribution and tra nsmission Consider owner-supplied materials. An owner l i nes may have specific material that they supply to the tra n s m i ssion or d istri bution l i nes exist or a re often conflict with l i g ht poles. Where insta lling contractor. As products have different proposed a n d where l i g hting is req u i red, the l evels of performance, the designer should gather designer should consult the local utility provider appropriate information specific to owner-supplied and i nvestigate applicable codes and standards material and use those prod ucts as the basis for to d etermine c l ea rance req u irements. Typica l ly, design. If the owner is supplying the materials, clearance from poles to overhead power l ines w i l l this fact should be clea rly noted and described b e defined b y federal reg u lations, state or provi ncial i n the bid or tender documents. (Note: The steps worker reg u lations, a nd/or the l ocal electrica l for pre-design of tunnel l i g hting will vary from util ity. Because req uirements may vary from area those l isted a bove. Refer to Chapter 14 for tunnel to a rea, it is not possible to esta b l ish sta ndard recommendations.) clearances. Typically, the higher the voltage of the overhead l ines, the g reater the clearance distance 5.4.2 Investigate Site Conditions. In some cases, req u i red. In the case of overhead transmission l ines, site conditions may dictate whether roadway l ig hting the local electrical util ity may define additional can be i nstal led, or may l i mit various aspects of the clearance req u i rements due to the potential sag design. Therefore, the fol lowing site conditions should of the transmission l ines. Line sag will vary with be i nvestigated: the change in a mbient temperature and power • Availability of power. The availability of power demand. is a major factor in determining whether roadway • l ighting can be provided. If power is not ava i lable, Where overhead power lines exist, the designer the local util ity should be consu lted, a n d cost should have the height a nd location oflines su rveyed estimates for power su pply should be determined. to determine a ppropriate light pole heights i n Proxim ity faci lities. order t o meet t h e cleara nce req uirements. I f the Prospective i nsta l lations i n c l ose prox i m ity to required clearances cannot be achieved, then the to ai rcraft landing 5-1 1 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities designer may consider locating poles on the side of require reg u l a r service for lamp replacement, and the road without power l ines, if possible, to achieve all will req uire service for clea n i n g . It is critical the recom mended light levels. If this is not possible, the l u m inaires be safely accessible via available the designer w i l l need to work with the l ocal utility service vehicles (used by those undertaking the to resolve the clearance issues through relocation maintena nce) with m i nimal disruption to traffic. of power l i nes, cooperative pole locations, or other The height l imits of maintenance equ ipment may influence pole height and l ocation, (see Chapter 9 means. Maintenance and Operations). Of pa rti c u l a r concern m ay be l i g hting at • intersections, where req u i red lighting levels are much higher than those of the approach roads zones and pole placement issues should be known and there is less flexibil ity with pole placement. and addressed (see Chapter 6, Section 6.9.3). To achieve the req u i red levels and u niformity, a designer may have to be creative with pole • reviewed for what may be problematic crash c l earance requirements for overhead power lines. When l ocating a n el ectrical system locations. This can be done by first driving, walking or cyc l i n g the road a n d esta blishing possible i n close problematic l ocations. M u n icipal agencies, road proximity to high voltage tra nsmission l ines (35 authorities, and maintenance contractors can be kV and g reater) the designer sho u ld contact the contacted to confirm whether problematic locations l ocal utility and review possible issues with induced have recorded any collision statistics. Problem a reas voltages from the overhead power l i nes on the should be identified and solutions d iscussed with u nderground wiring. Underg round wiring running the owner. para l l e l to the transm ission lines will typically be most affected. When desig ning i n a reas of close proxi mity to power l i nes, speci a l consideration should be given to the grounding of streetlight poles. 5.4.3 Defi ne Lighting Design Criteria. Prior to u n derta king a l ighting design, the designer should identify basic lighting criteria for the project, including the fol lowing: Environmental issues. The impacts of offsite glare, • as noted in the applicable chapters in Part 2 Obtrusive Light) should be considered for a ny - Design of this Recommended Practice. roadway. The designer should consider these issues prior to undertaking any design a nd be aware of Lighting levels and uniformity. Recom mended light levels and u niformities should be esta bl ished light trespass, and sky g low (refer to Chapter 4 - Historical safety performance. It is recom mended that an assessment of historica l crash data be placement and l u minaire wattage while meeting • Roadside safety considerations. Poles can be a potentia l hazard to errant motor vehicles. Clear • Pavement type and reflection factor. For com munity concerns and local req u i re ments. Local i l l u m ina nce ca lcu lations, the type of pavement l ig hting bylaws may also dictate the type of lighting w i l l affect the reflecta nce and the a m o u nt of that may be installed, and may dictate light trespass l ighting requ ired. (Refer to Section 3 .1 . 5 for more and sky g l ow l i m its. information.) Maintenance and operations considerations. • Partial or full lighting. The req u i re ment for fu ll or partia l l ighting should be determined by M a i ntenance consid erations should be pa rt of the roadway l i g hting desig n . Where poss i b l e, the warrants for the type of i nsta l lation under maintenance personnel should be consulted by consideration. ( Refer to the a pplicable chapters for those undertaking the roadway l ig hting desig n . In the facility u nder construction in Part 2 some cases, prod ucts with a higher i nitia l purchase definitions of full lighting and partial lighting.) cost can save significant operating or mai ntenance • - Design for Lighting bylaws. Determine whether the city, costs. Products specified should be both corrosion m u nicipality, state, or province has a lighting bylaw resistant that defines spi l l light and sky glow l i m itations, or 5-12 and d u ra b l e. Some l u m i n a i res will The Planning and Design Process requires specific l u m i na i re optics (e.g., fully shielded with lumen outputs documented by suppliers and l u m i naires). manufacturers. (Refer to Section 2.4 and Section 6.3 for more information on lamps.) 5.4.4 Perform Lighting Design. The designer should • select a suitable luminaire, obtain I ES-format photometric Luminaire optical distribution and BUG rating. L u m i n a i res are available in a variety of optica l files, and undertake the lighting design using computer distributions and BUG ratings, as noted in Section lighting design software as noted in Chapter 8 Computer 2.6.3 - Luminaire Classification System and BUG Applications. Lighting design is typically undertaken using Ratings. The desig ner should choose the best a "tria l and adjustment" process using computer design optical d istribution and BUG rating based on the software to apply the variables listed below to achieve requirements of the project. the optimal design. Typically, the more experienced the • Pole spacing. Pole spacing wi l l often have to be designer, the shorter the trial and adjustment period. As adjusted to suit d riveways, intersecting roads, and the photometric data of luminaires wil l vary from supplier other site-specific req u i rements. ( Refer to Chapter to supplier for similar products, it may be appropriate to review luminaire photometric reports from multiple suppliers. Variables that the designer should know for the lighting design include: • Light source. As noted in Section 6.3 Light Sources, there are many l ight source choices to consider. The designer needs to be capable of making a proper choice with respect to the project needs and req u i rements. • Total light loss factor (LLF). LLF is described in Section 3.1 .6. It is i m portant that it be identified and considered in the desig n. • - Highway and Interchange Lighting for more information on pole spaci ng.) Lighting design typical ly involves a process of "trial and adjustment" using computer design software u ntil the layout is optimized and the req u i red criteria are achieved. Different lighting designers will have different methods underta king lighting calcu lations and developing the desig n. Computer design software is a key part of the lighting design process, and it is the recom mendation of this document that all l ig hting design be accompl ished using a suitable software package. Pole type, pole height, and l uminaire arm length. The pole type, pole height, and l u m inaire arm length will often be defined by the owner. Where the designer is a l l owed to select the mounting height and l u m i naire a rm l ength, he or she should use the combi nation that provides the recom mended levels and u n iformities with the least a mount of infrastructure possi b le. (Refer to Section 6.2 for more information on mounting heights and arm lengths.) • 10 The pole height and confi g u ration, and the l u m i naire type, wattage, and l u men output may all be affected by a given streetscape concept developed by the architect. The designer may also face l i mitations for pole placement locations due to conflicts with street furniture or other feat u res. It is imperative that the desig ner work closely with the a rchitect or u rban designer in developing light pole locations and mounting heig hts so that the req u i red l ighting levels can be achieved. Pole offset. The pole offset will be defined by the clear zone and the abil ity to use a breakaway For those with less experience, a basic two-stage process device. (Refer to Section 6.9.2 and Section 6.9.3 for roadway l ig hting design is as fol l ows: for more information on pole offset and clear zone, respectively.) • • Stage 1 - Optimization Luminaire type. Many types of l u minaires, with different levels of performance, a re available for The opti m ization stag e should be underta ken on different appl ications. (Refer to Section 6.2 for tangent sections of roadways. The designer should more information on l u m inaire types.) select sections of roadway with consistent geometry to Luminaire wattage and lumen output. Luminaires confirm the optimal pole spacings. The pu rpose of this are typically available in a wide variety of wattages, stage is to determine the opti mal spacing for a given 5-1 3 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities section of road as a starting point. The optimization the benefit of optimization. Steps will be s i m i l a r to process i ncludes fou r steps. those previously described, with the spacing preset Step 1. Obtain photometric data files in I ES format a n d refined by trial and adjustment. The specific type from lighting suppl ier(s). These a re often available of calculation to be u ndertaken wil l va ry, depending on on suppl iers' websites. the type of criteria (ill u m inance, luminance, STV, vei l ing Step 2. In the l i g hting design software, i n put l u m i nance, as defined in Chapter 3 va riables such as road geometrics (number of l anes The recommended type of calculation is specified in and widths as wel l as medians), l ighting level and u n iformity, pavement type and reflecta nce, l ig ht l oss factor, lamp l u mens, preferred type of pole layout (e.g., staggered, one-sided, opposite, median; see Chapter 1 0), mounting height, l u m i naire arm length, l u m i na i re orientation, set back from edge of road, and l u m inaire ti lt (if req u i red). (Refer to Section 3.1 should - Calculation Elements.) The designer also take i nto consideration roadway cross-sections where steep s lopes could alter the the appropriate chapters in Part 2 - - Calculations). Design. Exa m ples of the com puter lighting calcu lations may also be found i n those chapters. When u nderta king calcu lations, the designer sho u ld also assess spi l l light i m pacts and meet the spi l l light level s defi ned in Section 4.3.1 - Recommended Acceptable Levels of Spill Light. mounting heig hts. 5.4.4.1 Designing H igh-Mast Lighting. For l i g hting large Step 3. Run the optim ization feature in the computer areas using high-mast lighting, the l ig hting calcu lation software. process is slightly different. The designer should use Step 4. Try alternative pole layouts and l u m i naires com puter design software to develop custom l ighting with different performance. This may i nvolve a templates for a variety of high-mast pole arrangements num ber of runs to verify optimal spacing. using various l u m inaire quantities and distri butions. This can be accom plished using va rious combinations Stage 2 - Design of i ndivid ual l u m inaires clustered on a g iven pole to create the most effective overal l distribution of light The design stage should involve adjusting the actual through trial and adjustment. By com bining efficient spacing to suit the road geometrics. Road geometrics, tem plates, the desig ner is able to produce optimal l ig ht such as d riveways, turn lanes, intersections, curves in the distribution for the g iven road geometry. The variables road, and other obstructions to pole placement will often will i nclude mounting heig ht, n u mber of l u minaires, require adjustment of the optim ized pole spacing. The designer should use the road geometrics to determine the actual spacing, which should not exceed the optimal spacing. This is best done with a copy of the electronic plans i mported into the computer design software to determi ne the required pole spacing. Once the spacing is established, the lighting design should be recalculated for the entire section of the road to confirm the lighting levels achieved. This may involve a n u m ber of trial and adjustment computer runs. Care needs to be taken to type of optics, orientation of optics, l u m e n output, light sou rce, and l u minaire photometric data. The custom tem plates wi l l show the pole location with l u m i nance or i l l u minance levels using contour li nes. The contour l i nes should represent different levels of i l l uminance or l u m i na nce. Templates a re typical ly developed in asymmetrical (long and na rrow) or symm etrica l (circular or square) patterns to suit road establish valid fixture-cycle calcu lation grids so that geometrics. The templates sho u ld be arranged on the the numbers generated are meaningfu l . (For additional site plan to show a pproximate pole l ocations, as shown information, see Chapter 8 in Figure 5-4. (If l u m i nance tem plates are used, the - Computer Applications.) observer location should be positioned correctly on The design of i ntersections, crosswa l ks, roundabouts, the road, accord ing to the d i rection of view.) These parking lots, and i nterchanges wil l follow a process methods w i l l give an a pproximate pole layout and a l l ow similar to designing a roadway section, but without for opti m ization through tri a l and adjustment. 5-14 The Planning and Design Process Figure 5-4. Example of high-mast lighting templates. Once the pole locations and pole d istri butions have is critical in determining the location for the lighting been opti m ized, a l i g hting calcu lation should be control cabi net, which will feed the lighting on the undertaken for the entire area of design, showing l ight system. Variables that need to be defined in the design levels on the roadway. The l ig hting calcu lations wi l l incl ude: require further refinement, using tria l and adjustment, • u ntil the desired l evel s are achieved. There is no voltage, size, and phasing needed, as wel l as the exact form ula for determining the m o u nting heig ht, need for metering. n u m ber of l u minaires, pole spaci ng, and l u m e n output. H i gh-mast l ighting design will typica l ly req u i re many calcu lations in trial and adjustment cycles to produce Electric service requirements. These include • Lighting control cabinet requirements. Typically, the road authority w i l l have a standard for l i g hting control cabi nets. If no standard exists, the designer a n optim ized desig n. or eng ineer should consider the fol l owing when When u ndertaking hig h-mast calcu lations, the designer should a lso assess spil l light effects and meet the spill specifying a cabinet: 0 light levels defined in Section 4.2.1 . Luminaire voltage. This should i nclude whether the l u m inaires will be fed phase-to-phase or phase-to-neutral by the bra nch l i g hting circuit. 5.4.5 Perform Electrical Design 0 Type ofmounting. The cabi net can be a sta ndalone The designer u nit on its own concrete fou ndation, mou nted on should verify potential service locations and ava i l a ble a pole, or mou nted in a service base. A service power supply voltages with the local util ity as defi ned base is designed as part of the l u m inaire pole to in Section 6.6 Electrical Distribution . This information house the l i g hting control cabi net. 5.4.5.1 Electrica l Design Elements. 5-15 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 0 A l u m i n u m or sta inless steel • should be used, for corrosion resistance. Cabi nets • Type of cabinet. events, whether fuse holders a re located in the security. The cabinet should have a N EMA 3 R or luminaire or in the pole hand hole • m o u nting hardwa re, preferably man ufactu red electrical equ ipment from harmfu l l ig htning and Internal components. Al l com ponents should be UL l isted, CSA a pproved, or equivalent as required power surges • by the owner. Com ponents should be located for when a large nu m ber of conductors are placed i n should be removable via screws or bolts. Breakers o n e cond u it and test switches sho u l d be easily accessible. Manufacturer. The man ufacturer should follow a q u a l ity control plan. Certification. The electrical com ponents and enclosure used i n the control cabinet assembly should bear a U L, CSA, or equiva lent label as req u i red by the owner. 0 Panel schedules and labels. The cabinet should contai n a panel sched u le identifying a l l circu its, voltage, and other relevant information. It should be mou nted on the front face or door. The m a nufacturer should provide their product n u m ber, tradema rk, and general information on a label located in an easy-to-read location. 0 Conduit fill Derating of a wi re's cu rrent ca rrying capability easy connection of field wiring. Components ° Surg e protection device (SPD) coord i nation to clamp the voltage at a ppropriate levels and protect from a l u m in u m or stainless steel. 0 Fuse sizing to protect l u minaires from overcu rrent should have doors that can be padlocked for better rating. The cabi net should have suitable 0 Voltage d rop for a l l circuits • Fault cu rrent calcu lations (may be req u i red where the fa u lt cu rrent exceeds 1 0 kA) The electrical design should be undertaken in strict accord a n ce with the N EC4 (U.S.), CEC5 (Canada), or N o rm a Ofi c i a l Mexicana NOM-001 - S E D E-201 2 l nstalaciones Electricas, Uti l izaci6n6 (Mexico), and any l oca l requirements. 5.4.6 Perform Geotechnical and Structural Design. L i g hting designs often i nvolve geotech n ical and structural eng i neering d e s i g n elements related to poles and fou ndations. In many cases, a road authority wil l u ndertake geotechnical and structural design of Metering. Where metering is req uired, the cabinet standardized materials such as poles and fou ndations should be desig ned to m eet the metering based on defined soils and structural desig n. req u i rements of the loca l uti l ity. 0 Shop drawings. Shop drawings of the cabi net 5.4.6.1 should e n g i neering may be req u ired to defi ne the shape be provided, showing equ i p ment Geotechn ical Engineeri ng. Geotech n ical mounting and cabinet fabrication details, along and depth of the pole support fou ndations based with a l ist of internal components, and make on soil conditions. Although many jurisd ictions w i l l and model n u m bers. Shop d rawings should be u t i l ize sta ndard fou ndations that are applica b l e to reviewed and approved prior to construction. known common soi l conditions, they will not apply to every situation. Because soils can vary g reatly over a • G ro u n d i ng and bonding • Method of measuring power consu mption (e.g., metering or flat rate) g iven a rea, a geotech nical engi neer may be req u i red to procure soil s a mples a n d verify that sta ndard foundations a re su itable for the given soil conditions. I n • Cond uctor sizi ng and insu lation • Conduit type and sizing • Type and location of junction boxes some i nstances, geotechnica l engineers w i l l b e req u i red to make recommendations for custom fou ndations, such as for high-mast lighting. Typical el ectrical 5.4.6.2 Structural Engineeri ng. Structural engineering calculations to be u ndertaken as part of any roadway is typically required for pole structures and support l ighting design include: elements. A road authority wil l often have sta ndard 5.4.5.2 Electrical Calcu lations. 5-1 6 The Planning and Design Process foundations. These may negate the need for a structural 5.4.7 Prepare Plans, Specifications, and Estimates design or geotechn ical design if the fou ndation is (PS&E). deemed acceptable for the soil conditions. Roadway lighting installations wil l typical ly involve the preparation of plans, specifications and estimates (PS&E). Modern pole suppl iers typically supply engineered pole designs to meet the wind loads for a g iven area. The lighting designer should determine the a ppropriate 5.4.7.1 Plans. As a m i ni m u m, plans should include: • structural codes and sta ndards for the a rea and make A pla n-view d rawing showing a l l proposed, existi ng, and future road geometrics (e.g., cu rbs and gutters, sure they a re followed. sidewalks, crosswal ks) and util ities. The designer should overlay pole l ocations, conduit and wiring, The Canadian Bridge Highway Design Code (CAN/ and the service l ocation on the plan. The drawing CSA-S6)7; the American Association of State Hig hway should have a legend and notes specific to the Tra nsportation Officials (AASHTO)'s LRFD Specifications desig n. A key plan should be i ncluded for larger for Structural Supports for Highway Signs, Luminaires, and projects. Traffic Signals8; and the Mexican Manual de lluminaci6n • Pole elevation d rawings, including pole and d rawings a re Vial9 define stru ctura l criteria and req u irements for fou ndation poles and fou ndations. ava i lable, a reference to the standards may m itigate deta i l s. If sta ndard the need to detail these items. Custom poles and foundations a re usually req u i red for • high-mast l i g hting applications. Where a custom pole l i g hting controls, and bra nch lighting circu its. If and fou ndation is req u i red, the process should include standard d rawings are available, a reference to the these steps: • standards may m itigate the need to deta il these The structural engi neer will assess pole load ing and items. define base reaction forces based on local wind • l oads and appl icable codes. • A geotechnica l engi neer w i l l use base reaction forces to esta blish fou ndation depth and sha pe. I n situations with h i g h base reaction forces a n d poor soils, pile su pport or other reinforcement of the soils may be req u i red. • The structural engineer will defin e fou ndation reinforcing and concrete mix design and w i l l produce a n i nsta l lation d rawing. • A schematic a nd/or one-line diagra m of service, Drawings signed and sealed by a Professional Engi neer l icensed i n the state or province where the project is being undertaken. Plans may a lso be prepared to i nclude lighting for temporary detours. 5.4.7.2 Specifications. Specifications are often unique to a g iven ju risdiction. The designer should contact the owner and request standard specifications used for that j u risdiction. Specifications a re typical ly provided in a specifications booklet by the jurisdiction, but may a l so The geotechn ical engi neer will defin e backfi l l req u i rements. be shown on the d rawings. Where a j u risdiction does not have standards, it will be up to the l i g hting designer to define the sta ndards in consultation with the road Additional i nformation may be found in Section 6.8 authority. - Foundations and Section 6.9 - Poles and Related 5.4.7.3 Luminaire Performance Document. A summary Hardware. sheet defining the performance criteria of the l u minaire is 5.4.6.3 Pole Attachments. Pole attachments may a helpful part of the bid documents. It lists the l ight levels i n c l u d e ba n ners, electrica l outlets, flower and u niformities that need to be achieved for various basket hangers, holiday decorations, traffic signs, or other roadway sections throughout the project. In addition, equipment that can affect structura l , e lectrica l , or the roadway classification, roadway geometry, and pole i l l u m ination designs. Careful consideration should be configuration deta ils should be listed so that the bidder taken when using poles that are on a breakaway device. knows the l u m i naire requirements for the project. 5-1 7 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 5.4.7.4 Estimates. Construction cost estimates may documents specific to the owner. Contract documents or may not be req uested by an owner, depending may be assem bled by the consultant or by the owner. on the circu msta nces. Where estimates a re requested As a m i n i m u m, the designer w i l l prepare the technical by an owner, it should be the responsibil ity of the specifications as wel l as define the payment items. design professional to prod uce accu rate estimates in accordance with the level of detail known. Cost Lu m in a i re photometric testing by a n i ndependent estimates can range from prel iminary estimates, which laboratory is required by some roadway authorities. are approximate in nature, to final deta iled costs. This can be written into the contract documents. It can provide, via design calcu lations, verification that Cost estimates can be categorized by "class," designated the actual performance of the l u mina ire w i l l meet by a letter from A to D, with a Class A cost estimate being l ighting design expectations. Given the large capital the most accurate and based on the most detailed investment required to i nsta l l roadway lighting, the cost information. of i ndependent l u m i naire testi ng can be an effective • Class A cost estimate. The most detailed cost way to determ ine whether the owner is getting what estimate, based on q ua ntity ta keoffs from final has been paid for. d rawings and specifications. Class A cost estimates • are often used to eval uate bids or tenders, secure Typically, payment items w i l l be unit price or l u m p sum, final fu nding, or provide a basis for cost control which w i l l genera l ly be defined by the owner's contract during construction. documents. A unit price contract should be used where Class B cost estimate. The cost estimate prepared cha nges thro u g h construction are a nticipated. after site i nvestigations and studies have been completed and the concept designs have been developed, to i l l ustrate and defi ne a l l major elements, includ i ng o utline specifications. This class of estimate is based on a project design report and pre l i m i nary desig n. • Class C cost estimate. This cost estimate, which is prepared with l i mited site i nformation, is based on probable conditions affecti ng the project. It represents the sum mation of a l l identifiable component costs (what is known). It may be used for program planning, establishing a more specific defin ition of cl ient needs, securing fu nding, or obtaining approva l in principle. • Class D cost estimate. This is a preliminary cost 5.4.7.6 Owner Review. The designer may be required to s u bmit PS&E documents to the owner for review at va rious stages thro u g h the design process. This will vary depending on the owner and their specific req u i rements. Changes recom mended by the owner should be undertaken or discussed further and clarified. 5.4.7.7 Quality Control (QC) for PS&E. It is recommended the firm u ndertaking the l ighting design empl oy a QC system i n order to maintain a nd, where req u i red, i m prove quality. Though review and checking are critical to any q u a l ity control prog ra m, additional considerations i nclude employee training and qual ity estimate that, due to little or no site i nformation, improvement. It is not the focus of this document to ind icates the approximate mag nitude of cost of recom mend such a program; however, the i mportance the proposed project, based on the client's broad of QC sho u l d not be overlooked by the design fi rm or req u i rements. This overa l l cost estimate may be the owner. derived from l u m p sum or unit costs as identified in the construction cost records for a similar project. It 5.4.8 Bid or Tender. may be used to obtain approval i n principle, and for specifications a re complete and have been reviewed discussion pu rposes. a n d accepted by the owner, the project is typically Once the d rawings a n d issued for bid or tender. The bid or tender process 5.4.7.5 Contract Docu ments. Contract documents will vary from jurisdiction to ju risd iction. The design shou l d include all specifications and bid or tender professional should consult the owner and confirm 5-18 The Planning and Design Process the process and the level of i nvolvement req u i red. The design is used as a basis for the owner's eva luation consulta nt may be req u i red to review bid or tender of the contractor's offer. The cost estimate is used by prices and provide a recom mendation for award by the the contractor to esta blish a competitive fixed price owner. bid. Final design, u nder this type of procurement, There are m a ny methods of project del ivery. The project is awarded. may be provided d u ring construction or after the del ivery method will affect the requirements for PS&E. Typical ly, the roadway l ig hting will be constructed as 5.4.9 Construction. Once the project has been awarded, part of a road works project, and the project will define construction typica lly begins. It is reco m m ended that the method of delivery. the design professional be retained to provide the fol l owing services: The two most common methods of project del ivery are design-bid-build (DBB) and design-bu ild (DB). • Design-bid-build (DBB). This is the more traditional • Respond to issues and q u eries through construction • Review shop drawings and prog ress d rawings • Review su bstitution requests or a lternate products method of design and includes a complete design proposed by the contractor with PS&E before the project is issued for bid or tender. The project is constructed, typica l l y, by the • • com p lex Define or eva l uate field changes that may be necessary to ensure that the insta l lation meets the (if req u i red). The desig ner w i l l often provide design intent engineering services throug h construction for the • Provide construction inspection services, including field reviews (periodic or fu ll-ti me) work to ensure it is in accordance with the design • (for then adjust the lig hting or electrical design as full design, plans, specifications, and cost estimate intent. m eeti ngs req u i red due to unanticipated circu mstances, and sub-consultant) for the project owner, producing a owner. The designer will review the contractor's construction projects) lowest qual ified bidder. Under DBB, the roadway lighting designer works d i rectly or indirectly (as a Atten d • Measure and record actual i l l u m i nation level s Design-build (DB). This is a n alternative method achieved of del ivery in which the owner or the owner's f l o od l i g h t i n g , engi neer defines req uirements throug h a request circumstances where l ig hting performance may be for proposals (RFP), and the contractor prepares in q u estion) the design and the bid, and builds the project for a fixed price. There a re many versions of DB, but • (typically u ndertaken h ig h -mast for lighting, t u n nels, or in Undertake a final field review and prod uce a l ist of any deficiencies that req u ire correction before the the basic idea is s i m i la r. Under DB, the roadway contractor can be released from the project and lighting designer works d i rectly, or indirectly as a fi nal payment made sub-consultant, for the contractor. The DB process is being used by many jurisdictions. It has been 5.4.1 0 Post-construction: Drawings. shown to tra nsfer some sched ule and cost risks to mended that t h e lighting contractor b e responsible for the contractor, and can shorten the time req u i red recording all construction changes on a cu rrent set of to move a project from design to construction. It is recom ­ design d rawings, as part of the contract req uirements. This is typica l l y done on a set of plans known as a red If a project is procu red as D B, the contractor retains line set. The roadway l i g hting designer should u pg rade a design professional to develop a defined level of design drawings to reflect the actual conditions and the roadway lighting and electrica l design as part of red line set. Fina l ly, a set of record d rawings should be the bid process. The level of design at this stage produced and tu rned over to the owner. varies. It is governed by the a mo u nt of detail the contractor needs to assemble a competent bid and Record d rawings (a lso c a l l ed as-built drawings or present a n acceptable design to the owner. The as-builts) a re i mportant for use in the mai ntenance of 5-1 9 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities the l ighting system and can be used as the basis for 5.5.1 future additions and upgrades. Maintenance personnel as construction cost) will vary widely for each a rea Capital Cost. should record a ny alterations to the roadway lighting depending on the state of the economy and the material system on the as-built d rawings. used. Labor and material costs typica l ly vary across If upgrades to a n existing l ig hting or electrica l system standard cost for a l i g hting insta l lation. Ca pita l cost (a lso known la rge reg ions. It is, therefore, not possible to establish a are being made, the roadway lighting designer should obta in cu rrent as-bu i lt d rawings, or develop as-bu i lt For budgeting purposes, it may be a ppropriate to establish d rawings from design d rawings and field i nvestigations. a per-kilometer (or per-mile) cost, or a unit pole cost. This cost should include wiring, boxes and conduit between 5.4.1 1 Post-construction: I ntegration and each set of typical poles. Capital cost estimates should be Commissioning. System integration is defined as the undertaken for each project as noted in Section 5.4.7 process of bringing together the component su bsystems Prepare Plans, Specifications and Estimates. - into one system and ensuring that the subsystems function together as a system . The system integrator 5.5.2 Operating Costs. Operating costs should include brings together discrete systems utilizing a variety of power and preventive maintenance costs. They a re techniques such as computer networking, enterprise typica l ly calcu lated on an annual basis. These costs a re application i ntegration, busi ness process management, used by a j u risdiction to esta blish operating budgets. and manual prog ramming. An owner may wish to esta blish a per- l u m i naire cost for power and maintenance. This can be u pdated on a Commissioning can be defined as the process of ensuring reg ular basis to reflect cu rrent labor and material costs, that all systems and components of a street l i g ht as well as power costs. system are designed, i nstal led, tested, operated, and maintained accord ing to the operational user needs When calculating power cost, the method of payment of the owner or fi nal client (refer to ANS/I/ES LP-8-20, used by the l oca l e l ectrical util ity w i l l need to be Lighting Practice: The Commissioning Process Applied to confirmed. Some util ities esta blish a monthly flat rate Lighting and Control Systems10). for va rious g iven l u m inaire wattages. Others use a set kilowatt-hour (kW. h or kWh) rate for street lighting. For large projects, this process usua lly comprises planning, execution, and control of many inspection If a kWh rate is defined as the method of calcu lating and test activities on "commissionable objects," such as power costs by the util ity, then the actual kilowatts management stations, data loggers, streetlight controllers, consumed should be calcu lated using data obtained circuits, communications infrastructure, subsystems, and from the d river or ba l last supplier's website. systems. A project that is well planned from the time of project conception greatly minimizes the time and cost The actua l costs per l u m i naire may be calcu lated: of integration and commissioning. It is important that all stakeholders active in the integration and commissioning kW x R = cost per hour , process communicate, as many interdependent project activities have the ability to slow the start-up activities. where R is the cost per k i l owatt-hour ($/kWh) charged by the util ity, and kW is the kilowatt rating More information on system integration and commissioning of the l u m inaire. can be found in Chapter 6, Section 6.1 0.4. Example: 0.2 kW x $0.06/kWh = $0.1 2 per hour. (Consult uti l i ty for actual cost of power.) 5.5 Calculating Costs As described in Section 5.2.2, costs a re typica l ly broken To confirm the yearly cost, it may be assumed that the down into capital, operating and l ife cycle costs. l u m i na i re wi l l be operating for 4,380 hours per year; this 5-20 The Planning and Design Process is then multipl ied by the hourly costs. The 4,380 hours high-mast and conventional davit lighting at a typical is based on the l u m inaire operating an average of 1 2 interchange a re shown in Figures 5-5 and 5-6. hours per day, 365 days a year. This may vary depending on the local uti l ity tariff. In the case shown, the davit l ig hting ($951 ,420.00) would Preventive maintenance activities, such as relampi ng mast lighting ($824,1 20.00). It should be noted that this have a higher estimated life cycle cost than the high­ and cleaning, can be budgeted . To determine these exa mple is not a n endorsement of hig h-mast over davit­ costs, one should consider the cost of the lamp, plus the style lighting. It is provided to give a general exam ple of la bor costs to insta l l the lamp and clean the l u m inaire. the considerations that need to be taken i nto account This cost is then divided by the years between relamping. when undertaking a life-cycle cost a nalysis. In the case of this example, i nflation has not been factored into the Example: Assu ming an HID lamp cost of $20.00 and a totals. Costs and information noted a bove should not be labor cost of $20.00 per l u m i naire for relamping and used in l ife cycle ana lyses, as they w i l l vary depending cleaning every fou r years (a typical HID relamping on costs for the given a rea. sched u le), then the cost for preventive mai ntenance wou l d be $ 1 0.00 per year per l u m inaire. 5.5.3 Life Cycle Cost. Life cycle costs are mainly used by designers to eval uate and compare different l i g hting systems, such as conventional and high-mast l ighti ng. Often a l i g hting system may have a less expensive capital cost, but when l ife cycle costs are considered, a l ighting system with a higher capital cost may result i n significant cost savings over t h e l ife o f the system. Life cycle costing will include the capital cost, as defined above, as well as operating costs over the estimated l ife of the system . Operating costs should i nclude power and preventive mai ntenance costs, which a re a lso calcu lated over the l ife of the system (typica l ly 30 years, a lthough this will vary depending on the g rade of the equ ipment used). It is doubtful that after 30 years of operation existing equipment would be reused. Therefore, no residual value should be considered. When life cycle 5.6 Verification of Lighting Levels 5.6.1 Verification by Calculation. Where verification of l i g hting l evels and uniform ity a re req u i red, the designer should first confirm the l u m i na i re type, photometric data, pole spacing, road geometrics, and l u m i na i re mounting height and run a computer l ig hting calculation. Performing this calculation will enable the designer to verify that the design will meet the l ighting criteria. Although there will be some variation between actual levels versus those calculated, this will be a g ood ind icator of what exists. 5.6.2 Field Verification. It may be appropriate to verify the performance of a l i g hting system by undertaking measurements i n the field. Field testing can be time consuming and may not be practical on high-speed or hig h-vol u m e roadways. Field testing w i l l costs are used to compare lighting systems, cu rrent often req u ire l a n e closures and traffic control, as the operating costs (defined at the time of the estimate) section of road being measured m ust be free of traffic can be used as the basis over the operating period. As to take measurements. Field testing is therefore only costs are most likely to increase over time, inflation may recommended i n the rare case where there is concern be factored in to provide a more accu rate estimate of with the performance of the l ighting system . the total costs. Undertaking field m easurements may b e im practical i n To calcu late the life cycle cost, one should determine s o m e scenarios where access t o t h e su rface being l it is not the capital cost of each l ig hting system as wel l as its practical. An example of a scenario where measurement operating cost over a 30-year period. would be d ifficult is a n external ly i l l u m inated sign 5.5.4 Life-Cycle Cost Calculation Example. Exa mples the sign, it would d ifficult to avoid blocking the light of l ife-cycle cost calcu lations for the comparison of sou rce while performing the measurement. mou nted a bove the roadway. Even if one cou ld access 5-21 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Highm st Cap it I Cost (In sta ll Cost s) Une No. Item UnH 1 30m highmast pole · h raise/lower system· 6 fixtures per pole; foundation ea 2 Condu· a n d v i ri n g 3 4 Qu•ntlty EsUIMted Cost Tot.I Cost 6 560,000.00 $360,000.00 m 1200 $40.00 548,000.00 Ug h ing control cabi net ea 1 $20,000.00 520,000.00 Junction boxes ea 12 $6,000.00 5500.00 Total Capltal Cost $414,000.00 High mast Oper ting Cost- Energy ( Energy Cost over 30 ye rs) Step No. 1 Eumpl• ukul.tlon Description 36 - l OOOW HPS fixtures Determine number of fixture.s Determine i nput vattage by mul ·plying fixture input 2 ament ·mes vo age. Wattage information is availab le 3.3 am ps x 347 volts = 1 145 watts. from fixture suppl ier 3 Determine o aJ ·1owatt.s by multiplyi ng the number of xtures by the input wattage 36 fixtures x 1 145 watt.s = 41 .12 kW Determine hourly power costs by multiplyi ng the total 4 s by the util" y rate. In this case have wil use $.065 s Determine 30 year cost. Assumi ng 4300 hours of lamp burn per year for 30 yea rs 41 .U kW x $0.065 = 52.68 per hour per kW hour (will need to be confirmed wit h utility) Tota l 30 Year Power Costs 5268 per hour x 4300 x 30 years = $145,720.00 $145,720.00 High mast Operating Cost- M intenance (labor and M teri als for 30 years) St.p No. Eumple ukul.tlon Description Determine relamping costs by determ·ning g roup 1 relamping sc edule and lam p cost. Assume r amping every 5 years 2 of raise lowing system. Estimate effort required and Determine labor costs for group relamp and servicing eq uipment and labor costs. 530.00 per lamp x 36 lamps x 6 (number of relamps requ ired over 30 years) = $6,480 51 25.00 per hour (crew of two and truck) x 16 hours (es ·ma ed effort) x 6 (number of relamps requ ired over 30 years) = $1 2,000.00 TotaJ 30 Year Ma intenance Costs $1 8,.480.00 Total Operating and Maintenance Cost $164,200.00 Total Life Cycle Cost $798,200.00 Figure 5-5. Example of life-cycle cost calculation for high-mast lighting. 5-22 The Planning and Design Process Davit Capital Cost (Install Costs} Item Untt Qu•ntlty Estlm.ted Cost Toal Cost ea 1 00 $3,500.00 $350,000.00 Condu· and wiring m 2500 530.00 $75,000.00 3 Ugh ing control cabi net ea 2 54,000.00 $8,000.00 4 Junction boxes ea 40 5500.00 520,000.00 Un. No. 1 2 1 1 m davit poles with 250 watt fixture; founda ·on Total Cap ital Cost $453,000.00 Davit Operating Cost- Energy ( Energy Cost over 30 ye rs) Step No. 1 Description Enmple ukulMlon 1 00 - 250- vatt HPS fixtu res Determ ine number of fixtures Determ ine input wattage by mul ·plying fixture input 2 rurrent ·mes vo age. \ attage information ts availab le 0.88 amps x 347 volts = 305 watts from fixture suppl ier 3 Determ ine otal ki lowatts by mu iplying the number of fixtures by the input wattage 1 00 x 305 watts = 305 kW Determ ine hourly power costs by mu iplyi ng the total 4 s by the uti l" y rate. I n th is case have wil use S .065 305 x S0.065 = 5 1 .98 per hour per kW hour tviii nero to be confirmed wit h utility) 5 Determ ine 30 year cost. Assumi ng 4300 hours of lamp burn per year for 30 years Tota l 30 Year Power Costs $1 .98 per hour x 4100 x 30 years = $255,420.00 $255,420.00 Davit Operating Cost- Maintenance (Labor and M terials for 30 years) St.p No. Description , rela mping schedule and lamp cost. Assume rela mping every 5 years Determ ine re lamping costs by determ·ning g roup Determ ine labor costs for group rela mp and servicing l of lamps using bucket trudc. Esti mate effort required and eq uipment and la bor costs. Enmple ulculMlon 520.00 per lamp x 100 lam ps x 6 (number of relamps required over 30 years) = $1 2,000 51 50.00 per hour (crew of two and bucket ruck) x 40 hours (esti mated effort) x 6 (number of relamps required over 30 years) = $36,000 Estima e pole knockdowns. Unlike highmast, davit lighting may be suscep ·ble to knockdown by erran vehicles if poles are not loca ed behind barriers. 3 F<>r this exampl e, no barriers are provided. In actual practice the annual for knockdowns can be calculated by consult ing with local maintenance crews and Assume hree knodcdowns per yea r, assuming he pole can be reused. 5 1 500 per knockdown x 3 knodcdo vns per year x 30 years= $1 35,000.00 reviewing knockdown statistics for similar installation s. Total 30 Year Maintenance Costs $1 83,000.00 Total Operating and Maintenance Cost $438,420.00 Total life Cycle Cost $891 ,420.00 Figure 5-6. Example of life-cycle cost calculation for davit-style lighting. 5-23 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Circu mstances where field measurements m ig ht be can be made in the pole hand hole at the base of the considered include the fol l owing: pole. Measurements should be taken phase-to-phase • • Refractors and reflectors have d iscolored due and phase-to-neutral. H i g h intensity discharge ( H I D) to aging, resu lting i n concern a bout the lighting l a m ps should be operated for at least 60 m i nutes to system performance. reach normal operating cond itions before voltage and Luminaire photometric data are not available current readings are taken. Where voltage drop from for calcu lations, and lighting levels need to be the service (main brea ker) to the l ig ht source exceeds recommendations set forth by the applicable e lectrical verified. • The lighting levels a re cal l ed into question during a col l ision i nvestigation. • There are public complai nts a bout excessive spi l l l i g ht, and s p i l l l i g h t levels need t o be verified. When comparing a computer generated d esign to field test resu lts, a nu mber of va ria bles can affect results. It is i m portant to consider that l u m i naire photometric measure ments a re ta ken in ideal conditions (the control led confines of a laboratory), not the u ncontrol led and variable conditions found i n the field. One should therefore expect variations between calculated val ues and those measured in the field; it is u n reasonable to expect field measurements to exactly match those calculated. Field measurements should be undertaken with an i l l u m inance meter if the design method is i l l u m i nance. Where the design method is l u m inance, a l u m inance meter may be used. However, due to the high cost of the meter and complexity of the req u i red test, a n i l l u minance meter may a l s o b e used. W h e n testing a l u m i nance design with an illu minance meter, one of the following methods should be used: • Perform both l u m i n a nce and i l l u m i n a n ce calculations (using the grid points). The i l l u m inance levels will be compared with the levels measured i n the field with a n i l l u m i nance meter. • Convert the measured i l l u minance to l u minance using the m u ltipl iers in Section 3.2 Roadway Lighting Metrics - General Information. 5.6.3 Electrical System Verifications. Because input voltage and amperage can affect the l ig ht output of a l u minaire, measurements should be made at the main service and at each l u m i na i re being tested, to verify that the proper voltage and a m perage are being delivered. Where l u minaires a re mou nted on poles, measurements 5-24 code, low input voltage may negatively affect the light output of the l u m inaire. An electrical engineer should perform the req u i red voltage d rop calcu lations to make the d etermi nation and recom mendations regard i ng the sup porti ng e lectrical distribution system . 5.6.4 Field Verification o f Lighting Performance. I nformation on field m ea s u re m e nts of l i g ht i n g performance m a y b e found i n Annex A - Street, H i ghway, Tu nnel, Measurements. and Parki ng Area Field The Planning and Design Process R E F E R E N C E S FOR CHAPTER 5 1. I l l u m i nating Engineering Society. ANSl/IES LP-1 1 -20, Lighting Practice: Envi ron m ental Considerations for Outdoor Lighti ng. New York: IES; 2020. 2. Federa l H i g hway Ad ministration. FHWA Lighting Handbook. Washington, DC: FHWA; 201 2. (FHWA-SA-1 1 -22). 3. American Association of State Highway and Tra nsportation Officials. A Policy on Geometric Design of Hig hways and Streets, 7th ed. Washington, DC: AASHTO; 201 8. 4. National Fire Protection Association. National Electrical Code. Washington, DC: NFPA; 201 7. (NFPA 70). 5. CSA G roup. Canadian Electrical Code Book, 23rd ed. Ottawa, O N : CSA G ro u p; 201 6. 6. Norma Oficial Mexicana. lnstalaciones Electricas, Utilizaci6n; 201 2. Online: http://dof.gob.mx/nota_deta l le.php?c odigo=5280607&fecha=29/1 1 /201 2. (NOM-001 -SEDE-2012). 7. CSA G roup. Canadian Hig hway Bridge Design Code, 1 1 1h ed. Ottawa, ON: CSA G ro u p; 201 4. (CAN/CSA-S6-14). 8. American Association of State Hig hway Tra nsportation Officials. LRFD Specifications for Structural Su pports for H i g hway Sig ns. Washington, DC; 201 8. 9. Manual de l l u m i naci6n Vial: Carreteras, Bou l evares, Entronq ues, Viaductos, Pasos a Desnivel y Tu neles. Secretarfa de Comu n iaciones y Transportes; 201 5. Onl ine: www.sct.gob.mx/fileadmi n/DireccionesGrales/DGST/Manuales/ Manual_i l u m inacion/Ma nual_de_ l l u m i nacion_Vial_201 5.pdf. (Accessed 2021 J u l 29). 1 0. I ll u m i nating Engi neering Society. ANSI/I ES LP-8-20, Lighting Practice: The Comm issioning Process Applied to Lig hting and Control Systems. New York: I ES; 2020. 5-25 Lig hti ng System Com ponents Cha pter 6 CO N T E N TS 6.1 Selecting and Specifying Products . . . . . . . . . 6-1 6.5.3 Sou rces for I nformation on System Components . . . . . . . . . . . . . . . 6-27 6.1 .2 The I m portance of Qual ity in Product Selection . . . . . . . . . . . . . . . . . 6-1 6.6.2 Power Su pply . . . . . . . . . . . . . . . . . . . . . 6-29 6.1 .3 Other Key Selection Criteria . . . . . . . . . 6-1 6.6.3 Metering . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-29 6.1 .4 Capital (Su pply) Cost i n 6.6.4 Power Distri bution Cabinets . . . . . . . . 6-30 Available Equ ipment . . . . . . . . . . . . . . . . 6-1 6.6 6.3 6.4 Types of Lighting and Mounting 6-3 . . . . . . . . . . . . 6.7 . . . . . . . . . . . . . . . . . . . . 6-28 E lectrical System Components . . . . . 6-28 . . 6.6.5 Power Q u a lity Considerations . . . . . . 6-3 1 Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Typica l Cond ucto r Types . . . . . . . . . . . 6-32 6-32 6.2. 1 Bollard Lig hting . . . . . . . . . . . . . . . . . . . . . 6-3 6.7.1 6.2.2 Decorative Lighting . . . . . . . . . . . . . . . . . 6-3 6.7.2 Overcu rrent Protection . . . . . . . . . . . . . 6-32 6.2.3 H orizontal Arm-Mou nted Lighting . . . 6-4 6.7.3 Voltage Drop and Fa ult 6.2.4 H ig h-Mast Lighting . . . . . . . . . . . . . . . . . 6-6 6.2.5 Wa l l Mou nted Lighting . . . . . . . . . . . . . 6-1 2 6.2.6 Roadway Lighting on Uti l ity Poles . . 6-1 3 6.7.5 Conduit . . . . . . . . . . . . . . . . . . . . . . . . . . 6-33 6.2.7 Flood l ig hting . . . . . . . . . . . . . . . . . . . . . . 6-1 4 6.7.6 J u nction Boxes . . . . . . . . . . . . . . . . . . . . . 6-33 6.2.8 In-Roadway Lights . . . . . . . . . . . . . . . . . 6-1 5 Light Sou rces Cu rrent Calcu lations . . . . . . . . . . . . . . . . 6-32 6.7.4 6.8 G rounding and Bonding . . . . . . . . . . . 6-32 . Foundations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-33 6-1 6 6.8.1 Concrete Fou ndations . . . . . . . . . . . . . . 6-34 6.3. 1 Light Emitting Diode (LED) . . . . . . . . . 6-1 8 6.8.2 Steel Screw-In Type Fou ndations . . . 6-34 6.3.2 High I ntensity Discharge ( H I D) . . . . . . 6-1 9 6.8.3 Direct-Burial Poles . . . . . . . . . . . . . . . . . . 6-35 6.3.3 Fluorescent . . . . . . . . . . . . . . . . . . . . . . . . 6-20 6.3.4 Induction (E) . . . . . . . . . . . . . . . . . . . . . . . 6-22 6.9.1 6.3.5 Plasma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-22 6.9.2 Pole Placement (Spacing) . . . . . . . . . . . 6-37 6.3.6 Low Pressure Sod i u m (LPS) . . . . . . . . . 6-23 6.9.3 Clear Zone Req u i rements . . . . . . . . . . . 6-38 6.3.7 I ncandescent . . . . . . . . . . . . . . . . . . . . . . 6-23 6.9.4 Breakaway Bases . . . . . . . . . . . . . . . . . . . 6-38 6.9.5 Pole Attachment Hardwa re . . . . . . . . 6-38 Luminaires . . . . . . . . . . . . • . . . • . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.9 6-23 6.1 0 Poles and Related Hardware . . . . . . . . . . . . . 6-35 Pole Materia ls . . . . . . . . . . . . . . . . . . . . . . 6-35 . Roadway Lighting Control Systems . . . . . . . 6-39 6.4.1 Luminaire Photometric Performance . . 6-24 6.4.2 Special Considerations 6.1 0.1 Control Tech nologies . . . . . . . . . . . . . . . 6-39 for Roadway Lu m i naires . . . . . . . . . . . . 6-24 6.1 0.2 Ada ptive Lighting Design . . . . . . . . . . 6-44 6.1 0.3 Ada ptive Lighting Operations . . . . . . 6-49 6.1 0.4 I ntegration and Commission ing . . . . 6-5 1 6.4.3 6.5 Electrical Distribution 6.6. 1 Product Selection . . . . . . . . . . . . . . . . . . . 6-2 6.2 H I D and F l uorescent 6.1 . 1 Alternative Power Sources . . . . . . . . . . 6-24 Luminaire Components . . . . . . . . . . . . . . . . . . 6-25 6.5.1 Housings . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-25 6.5.2 LED System Components . . . . . . . . . . . 6-25 References for Chapter 6 . . . . . • . . . . . . . . . . . . . . . . . 6-54 Chapter 6 Lig hti ng System Co m ponents T Part 2 his chapter describes typical equ ipment and design considerations for roadway lighting and for facilities that use s i m i l a r equipment. Because equipment and design for tunnel lighting and sign lighting are of a special ized nature, discussions related to the equipment for these facilities are found withi n their respective chapters i n - Design: tunnels in Chapter 14 and s i g n s in Chapter 1 8. This chapter also describes the process for selecting 6.1 Selecting and Specifying Products equipment and system components. It compares typical A key task for the roadway l i g hting designer will be the options and choices designers will face when desig ning selection and specification of products and equipment. roadway l ig hting systems. This section provides assistance in this regard. The pu rpose of this chapter is to promote the effective 6.1 .1 use of products and design strateg ies, as wel l as to Equipment. promote the consideration and a pplication of new lig hting e q u i pment that is marketed and ava i lable and innovations throughout North America. One of the challenges for and new technolog ies a re reg u larly i ntrod uced, it is the designer is attaining knowledge of what products the responsibility of the desig ner to stay cu rrent with are available. While many consulting firms maintain emerg i n g tech n o l og ies. Beca use product refinements and new products ava i l a ble in order to deliver the best va lue to the client. Prior to specifying a ny new technologies, the desig ner should assess the suitabi lity of the technology for its g iven appl ication and should consider both capital a n d operational costs (see Sections S.2.2 and S.S). Where utility l ease lighting ownership is transferred to tra nsportation or m u nicipa l a uthorities, the system may have to be mod ified to meet loca l or national electrical codes and standards. The reader may a lso fi nd it helpfu l to know that there are two American Nationa l Standards I nstitute (ANSI) committees that develop standards affecting roadway l i g hting equipment. These a re C1 36, the Roadway Sou rces for I nformation on Available Many manufactu rers produce outdoor extensive product catalog l ibraries and reg u l a rly review new products with man ufacturers a n d suppl iers, designers may have difficulty keeping cu rrent on new or existing products. I nformation on many products may be found online on manufacturers' websites. 6.1 .2 The I mportance of Quality in Product Selection. Quality relates to the featu res and characteristics of a product that bear on its a bi lity to satisfy stated or im plied needs. Qual ity also includes the attributes of d u ra b i l ity, reliabil ity, and environmental compati bility. Q u a l ity could be overlooked if l ow price is the primary criterion for product selection. Quality, however, sho u l d b e a key consideration i n product selection. Typica l ly, focusing on price alone w i l l not del iver best-va lue installations when compared to a process that includes the scrutiny of quality considerations. and Area Lighting Committee, and C137, the Lighting System s Committee. Committee C 1 36 deals primari ly The use of high-qua l ity products is critical to prolonging with electrica l, mecha n ica l, and i ntercha ngea b i l ity the overa l l operating life of roadway l ighting systems. req u i rements, w h i l e Comm ittee C 1 37 focuses on Ca lculating overal l l ife cycle costs is discussed in Section l u m i na i res and controls as a coord inated system . As S.S. of this writing, Com m ittee C 1 36 has several standards under devel opment involving revenue-grade power 6.1 .3 Other Key Selection Criteria. metering, remote monitoring and control, and sensors q u a l ity, other key considerations when specifying a attached to l u m i na i res. product should include: In addition to 6-1 ANSl/IES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities • Cert ification. e l ectrical or parts will not be readily avai la ble, the designer l i sted, or should inform the owner to consider purchasing recognized by a nationally recogn ized testing replacement u nits or parts to stock for maintenance laboratory (N RTL) and, i n the U.S., a pproved by pu rposes. components L u m i na i res should be and certified, OSHA. These organizations, such as Underwriters' • • req u i rements. M a i n t e n a n ce considerations include ease of access for servicing, as wel l as mai ntenance frequency and level of l ist these products to the appropriate U L and North service req u i red over the product's antici pated American safety sta ndards. useful l ife (refer to Chapter 9). Product featu res and photometric perform a nce. industrial design decisions may result in reduced Photometric comparison of l u m i naires is critical to or increased time needed to perform mai ntenance selecting the best prod uct for a given appl ication. activities. Comparisons should be based on photometric data procedures for the product under consideration provided by the supplier from an independent should be understood and exa m ined to determ ine testing laboratory. The testing lab should have whether m a intenance activities will be costly National to perform. Will the l u m i naire external featu res L u m i n a ire Vol u nta ry Laboratory Accred itation Typical mai ntenance req u i re m ent Program (NVLAP) approval as administered by the accu m u l ate debris? How easy or d iffi c u lt w i l l the U.S. National Institute of Standa rds and Technology optical e lements be to clean? • Ease of installation. Consideration for how outdoor Luminaire BUG rating. In general, the "U" and l i g hting products are i nsta l led is a n im portant "G" parts of the BUG rating should be as low as aspect. Designers should coordinate with other practicable to meet the needs of a project and local discip l i n es such as civil, struct u ra l , e lectrical, ordinances (refer to Section 2.6.3). and landscaping d u ring the design process. It is Durability. Dura b i lity is the capabil ity of a product im portant to understand how poles can affect to resist deterioration, damage and corrosion underg round util ities, the potential for mounting u n d e rsta nd the luminaires on existing structu res, how l u m i naires potential for vandalism and the corrosive nature will be electrica l ly fed, and potential i mpacts to of the environm ent for the project and relate new and existing trees so that i nsta l lation and those varia b les to the specific prod ucts u n d e r constructab i l ity a re addressed before a lighting consideration. package goes to bid. over time. • M a i ntenance Canada (cUL), l ntertek (ETL), or CSA Group (CSA) can (N IST). • • La boratories (U L), U nderwriters' Laboratories of Aesthetics. Desig ners s h o u l d Prod ucts sel ected s ho u l d be • Operations cost. Similar products can resu lt in aesthetically compatible with their surroundings. varying cost of operations. This is particularly true Manufactu rers offer a wide range of eq uipment with of products that consume energy. The designer respect to shape, confi g u ration, colors and styles. should review operational costs when specifying Similar or identical appearing products should be products and choose products that a re econom ical used, if possible, when the new insta l lation wil l be to operate g iven the performance req uired. integrated with existing equ ipment. The height of lighting structures should be visual ly compatible • If products a re scrutin ized using the above criteria, the with the height of other structu res i n the a rea. owner is l i kely to end up with the best val u e, although Availability. Custom or decorative products and not necessarily the lowest capita l cost. products manufactured i n small qua ntities often 6-2 have long l ead times. Designers should verify 6.1 .4 Capital (Supply) Cost in Product Selection. that the products selected w i l l be available to The capital cost of a n item (also known as supply avoid construction sched u l e i mpacts, and should cost), though not listed previously, is an i m portant confirm that parts or complete replacement u nits consideration. Supply costs, however, should not be will be available fol lowing insta l lation. If products the primary factor when selecting products. To assess a Lighting System Components product's true cost, other factors need to be considered to confirm "best va l ue." (See Sections 5.2.2 and 5.5 for additional i nformation.) 6.2 Types of Lighting and Mounting This section defines typical lighting equipment that wil l be used in the design of lighting for roadways and associated facilities such as intersections, weigh stations, rest areas, walkways, and parking facilities. Lighting equipment for tunnels is discussed in Chapter 14; sign lighting equipment is discussed in Chapter 1 8. Because the suppl iers, manufacturers, and owners use different terminology Figure 6-1 . Typical bollard lighting. (Photo cou rtesy of Lumec) to define types of poles, there is no accepted standard industry nomenclature for pole types. Pole and luminaire be a m i n i m u m of 600 mm below g rade to ensure that terminology may therefore vary in different regions. the post does not lean over time. Deeper fou ndations should be considered where frost heaving is a concern. 6.2.1 Bollard Lighting. Bollard lighting is low level l ig hting used for i ll u m i nating pedestrian facil ities such 6.2.1 .2 Bollard Lighting Design Applications. Bol lard as pathways, wal kways, and stairs that are o utside a l ighting is typical ly used for pathways and plaza a reas typical road a l l owance. Bollards serve as g u idance and where "unobtrusive l i g hting" is req u ired . Bollard lighting accent lighting for narrow a reas and typical ly a re 1 .2 m will typical ly delineate a pathway. Bollard lighting will or less in height. not provide the req u i red amount of l ight for facial recognition, however, so it should not be considered When locating bol lards adjacent to roadways, m u ltiuse in a reas where secu rity is an issue. Due to their size and pathways, bicycle-only pathways, or wa l kways, the low mounting heig ht, bol lards are easy to service. As a desig ner should refer to national or loca l codes for result, they can be useful in areas where maintenance m i n i m u m pole offsets for cyclists. access via service vehicles is l i m ited. 6.2.1 .1 Bollard Lighting Equipment. Bollard posts are Bol l a rds are not recommended for use on or adjacent to availa ble i n a variety of materials, such as concrete, roadways, beca use their low m o u nting heig hts cou ld be steel, fiberglass, and a l u m in u m . They are a lso available distracting to road users. in a wide variety of styles, colors, and finishes. The post material should be closely reviewed for durability with 6.2.2 Decorative Lighting. The low mounting heights of respect to the type a nd location of the insta l lation decorative luminaires provide "human-scale" illumination, because bollards a re very susceptible to va ndalism in contrast to typical horizontal or arm-mounted or high­ due to their low heig ht. A typical bollard insta l lation is mast poles. Poles and luminaires for decorative lighting shown i n Figure 6-1 . usua l ly have a distinctive look, which is appealing to architects and urban designers and may be consistent with Optical systems for bol lards are available in a variety of a particular architectural theme. These types of l u minaires light d istribution patterns, wattages, and l i g ht sources. are sometimes known as post-top, pendant-mount, or teardrop luminaires. Decorative luminaires are commonly Bol lards should be installed on concrete fou ndations used for lighting commercial areas and subdivisions. These and connected with anchor bolts so that they can streets are usually up to 1 1 m wide. They may also be used be easily replaced if da maged. Bollard posts of the to light adjacent pedestrian facilities such as walkways direct-burial type should be surrounded by concrete and plaza areas. Examples of various decorative luminaire backfil l . Em bed ment of foundations or posts should styles that may be used are shown in Figure 6-2. 6-3 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities should be chosen only if they have good optical control a n d appropriate BUG ratings. Decorative style l u m i naires are typica lly l ess efficient than horizonta lly mou nted l i g hting. Therefore, they req u i re reduced pole spacing, increasing the cost of the insta l lation. They a re typically used in areas with high pedestrian volu mes and sho u l d be sized to a more human scale. Post-top l u m i naires may also be mou nted pa rtway up the shaft of a davit-style, mast-arm, or truss-style l ig ht pole to e n ha nce sidewa l k l ig hting and create a specific look. 6.2.3 Horizontal Arm-Mounted Lighting. This style of l u m inaire is commonly referred to as a "cobra-head," which it resem bles. They are the most common styles of l i g hting used for roadways and associated facilities, including i ntersections, parking lots, weigh stations and Figure 6-2. Typical decorative luminaire styles. (Photo courtesy of Lumec) rest a reas. Examples of this style of l ig hting with several styles of mounting arms a re shown in Figure 6-3. Davit-style arms consist of a vertical shaft or pole with 6.2.2.1 Post-Top Lighting Equipment. Post-top lighting a bent arm to position the l u m inaire over the roadway. structu res consist of a fou ndation, pole, and l u m inaire The main advantage of the davit-style over the truss­ (or multiple luminaires). Lu minaire mounting heig hts styl e or mast-arm is that the bend w i l l often offer typically range from 3 m to 9 m. additional cleara nce to overhead power l i nes. Truss-style Manufacturers offer many options with respect to the type of arm. The main advantage to the truss-style arm is simi lar to the davit-style with the exception of the style of decorative l u m inaires. Aspects of decorative is it can extend further over the roadway as result of l u m i na i res that should be specified include style, color, the additional support provided by the truss member. type of fi nish, wattage, l ig ht sou rce, and type of optics. The mast-arm is typica lly is a bracket that is bolted to Poles a re typically manufactu red from cast iron, steel, a l u m i n u m, concrete or fiberglass. They are attached to a concrete fou ndation using anchor bolts. 6.2.2.2 Decorative Lighting Design Applications. A desig ner needs to be careful when selecting decorative l i g hting, as many ava i lable products have poor control of the distribution of their light output. This can make the l u m i naire very i nefficient and costly to operate, resulting in poor value, and may result in u nwanted spi l l l ight, sky glow and glare. Architects and urban designers may specify decorative l u m i naire products by focusing only on aesthetics or the architectural theme without Figure 6-3. Typical davit-style (left), mast-arm (middle) considering optics. I n general, decorative l u m i naires and truss-style (right) mounting arms. 6-4 Lighting System Components the l u m i na i re pole or shaft. The main advantage of the mast-arm style is that the a rm can be combi ned with a decorative style l u m i naire for a distinctive look. Any of these arm types can be fabricated with an upsweep e lement to increase the m o u nting height of the luminaire above the pole heig ht. 6.2.3.1 Lighting Equipment. Roadway and a rea lighting systems include a fou ndation, a pole with cantilevered arm (s), and a l u minaire (or m u ltiple l u m inaires). Luminaire mounting heights are typical ly 7.5 m to 1 5.0 m. A typical davit-style arm length is 2.5 m, although manufacturers Fig ure 6-4. Cobra-head luminaire. may offer a wide range of arm lengths and diameters to meet the req u i rements of specific agencies. Truss-style When specifying poles ta l ler tha n 1 1 a rms are typical ly 2.5 m to 5.0 m in l ength. Mast a rms are designer should verify that the mai ntenance equipment typical ly 1 .0 m to 4.0 m in length. Decorative mast a rms owned or used by the jurisdiction servicing the lights a re sometimes formed from cast metal for a distinctive look. Poles a re typically available with single or m u ltiple a rms. Poles with two arms are referred to as dou ble-arm poles and are commonly used in the medians of divided highways. The davit-style pole example in Figure 6-3 is a double-arm pole. When the l u m i naire is mounted on a davit-style, mast­ a rm, or truss-style arm, it is normal ly perpendicular with respect to nadir (para llel to the roadway). Manufacturers offer many selections with respect to the style of the l u m i na i re for cobra-head -style meters, the has the appropriate vertica l and horizontal reach to access the l u m i naires. The selection of actual l u m inaire wattages and poles heig hts will be based on the width of the roadway a n d type of pole spacing (staggered, single sided, or opposite). Where vertical i l l u m i nation is required for m i d b l ock crosswalks and rounda bouts, higher wattages or shorter poles may be req u i red to achieve the vertical i l l u mina nce levels req u i red. There is no exact formula for establishing pole height. However, tal le r poles may be helpfu l in achieving u niformity requ i rements. Desig ners should be very cognizant of mounting heig hts in residential a reas because taller poles may resu lt in u nwanted spi l l l ig ht and glare for adjacent properties. Selecting the proper pole height l i g hting. Lu m i n a i res a re ava ilable i n various styles, requ i res balancing efficiency in ach ieving i l l u m i nation colors, wattages, light sou rces, and optics. Cobra-head levels with reducing obtrusive l i g ht (see Chapter 4). l u m i naires are available with a d rop refractor, sag lens The following considerations a lso apply to the design of or flat g lass lens. Lower wattage l u m i naires may a lso use davit-style, truss-style, and mast-arm roadway lighting: a polymeric lens. An example of a typical cobra-head • l u m i naire is shown in Figure 6-4. On roads with wide medians or concrete median barriers, dou ble-arm poles may be used as long as req u i rements for the clear zone are met (see 6.2.3.2 Roadway Lighting Design Considerations. The Section 6.9.3). An example of double-arm median key to designing with davit-style, truss-style, and mast­ l ighting is shown in Figure 6-5. a rm l u m i naires is selecting the optimal m o u nting height and light output combi nation to maximize the efficiency • L u m i na i res with flat- g lass optics tend to l i m it obtrusive l ig ht and reduce g la re for roadway users of the system g iven the pole spacing req u i rements. and for properties with a view of the l i g hting Poles are ava ilable i n several sta ndard mou nting heig hts system, better than those with d rop refractors or with va rious cantilevered arm lengths to suit many sag lenses in most cases. The performance of flat­ standards. glass l u m i naires is so d ramatic that local residents 6-5 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Figure 6-5. Double-arm median lighting, single-arm on-ramp lighting. have been known to complain that the l ight is off distribution that has its maxi m u m output toward or d i m i nished after l u m i naires with d rop-refractor nadir, as it will contribute more reflected l ig ht optics have been replaced with flat-glass optics. u pward, thus contributing directly to sky glow. The complaint, due to reduction in the size and • • intensity of l u minaire (glare) sou rces, is that the flat­ 6.2.4 High-Mast Lighting. High-mast lighting is shown glass fixtures are "not bright enough," even though in Figure 6-6. Hig h-mast l i g hting is a very effective the reduction i n glare actually i mproves visibil ity. method of i ll u m i nating freeway interchanges, or large It should be noted that l u m i na i res with d rop areas such as tol l plazas and parking areas. High-mast refractors tend to be more efficient i n terms of l ig hting consists of clusters of l u minaires mou nted on d istributing lighting out of the l u m i na i re than flat­ ta l l poles (typica lly 18 m to 55 m). The l u m i naires may g lass fixtu res, but there is less control over sky g l ow be positioned on a ring that can be lowered from the and spill l ight. top of the pole using a winch d rive u nit. That way the A sag-lens optical system is considered a l u m i na i res may be easi ly serviced at g round l evel. comprom ise between a l u minaire with flat g lass and one with drop-refractor optics. A sag l ens may Advantages and d isadvantages to hig h-mast lighting be a good choice when retrofitting a l u m i naire with include the fol l owing: d rop refractor optics. • 6-6 • Improved vehicle safety. Fewer poles at g reater Ca refu l consideration s h a l l be made to l i g ht offsets from the roadway than trad itional l ig hting d istri bution. It may be advisa b l e not to use a should improve roadway user safety, assu ming the Lighting System Components Figure 6-6. High-mast lighting. (Photo courtesy of WSP) • poles are not susceptible to i mpact. If poles are features. H i gh-mast systems, however, are far more placed too close to the roadway and not properly complex to design and insta l l . They wi l l req u i re a protected, then the level of safety will be reduced. much g reater level of expertise on the part of the Improved visibility. The peripheral field of view designer and insta ller. for the roadway user is typically m u ch better • • Wasted l ight and inefficiency. The light from i l l u m i nated, thus i m provi ng overal l visibility for high-mast poles is typica lly not wel l controlled. As roadway users. a result, areas off the roadway may be i l l u m i nated. Less clutter. In most cases, fewer poles will e l i m i nate Depend i n g on i nterchange layouts, hig h-mast the visual clutter associated with traditional l ighting. lighting may use more energy tha n traditional A related d isadvantage is that the taller poles may l i ghting, resulting i n increased power costs. affect valued views. • • • Potential increase in offsite impacts. As the Ease of maintenance. Lane closures for h i g h ­ l u m i na i re mounting heig hts a re increased, they are m a s t mai ntenance should n o t be req u i red i n more visible from l ocations off the roadway. This can circumstances where poles are located with su ita ble affect i n daytime views (i.e., those of local residents) offset from the roadway to a l l ow a mai ntenance as wel l as create concerns a bout obtrusive l ig ht at vehicle to park near the pole without affecti ng nig ht. Lu m i n a i res with internal louvers can m itigate traffic. I n circu mstan ces where the poles a re obtrusive light by shielding the view of the light mounted in na rrow medians, lane closures may be sources. Shielding can a lso be accomplished with req u i red. external shields. Exam ples are shown in Figure 6-7. Design and construction. The use of fewer poles It should be noted that the addition of internal or results in fewer design conflicts with other roadway external shields can reduce the efficiency of the 6-7 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Figure 6-7. Examples of high-mast internal louvers (left) and external shields (right). (Photo courtesy of Quality Lighting) • l u m i na i re and can affect its light distri bution. This the foundation. Both the pole and the footing req uire may result in reduced pole spacing and a n i ncrease structural design based on investigation of local wind in the n u m ber of l u m i na i res needed. l oa d i n g . Footing and fou ndation designs req u i re Additional equipment may be added to the g eotech nica l a n a lysis to verify soil conditions and poles. H i g h-mast l i g hting provides l ocations determine fou ndation size and shape. for cameras with pa nora m i c views for traffic surveillance and secu rity. If a ra ise-lower system is used to service the l u m inaires, it can a lso be used to service the camera. When a complex i nterchange req u iring fu l l i l l u m ination Luminaire is made u p of numerous on-ra m ps and off-ram ps, high-mast lighting should be considered, particularly if residential housing is d istant from the i nterchange (at Top Section least 1 .0 km away). 6.2.4.1 High-Mast Roadway Lighting Equipment. A high-mast lighting system is typica lly made up of the components shown in Figure 6-8. H i gh-mast poles are typically avai lable in mounting heights ranging from 20 m to 55 m and are provided with Electrica l Panel a base plate to attach the pole to a concrete fou ndation. High-mast foundations may be bored footings or the cast-in-place, spread-footing type, and are designed for the individual pole loading and soils. Bored footings are commonly used and less costly than spread footings. However, spread footings are used where bored footings cannot be used, such near underg round util ities. In areas of poor soils, piles may be req uired to support 6-8 Bottom Section Figure 6-8. Typical high-mast raise-lower (non-latching) system. (Gra phic courtesy of DMD & Associates Ltd) Lighting System Components Hig h-mast poles are most often made up of multiple An a l ternative to the typical h i g h-mast d ow n l i g ht round or m u ltisided steel shafts that "sl i p-fit" together styl e of l u m i n a i re a re floodlig hts, which can a l so work on site. This a l l ows the poles to be easily transported to effectively. Flood l i g hts will be of the most benefit the construction site in standard truckloads. At the job on tangent secti ons of a m u ltiple l a ne roadway. site, the sections are hydra u l ically jacked together. The Flood l i g hting will a llow for i ncreased pole spacing, lowering device is assem bled, and the pole is erected. red ucing the n u m ber of poles. The use of flood l i g hts Most steel poles are galvanized, but other corrosion s h o u l d be avoided at i nterchanges, as g lare i m pacts resistant coatings a re avai lable. may be difficu lt to assess and control for the large Hig h-mast l u m i naires with optics desig ned to m i n i m ize g l a re are recom mended to improve visibil ity for roadway users. A l ow-"G" BUG rating (see Section 2.6.3) can be helpfu l here. Lum i n a i res a re ava ilable in symmetrical (ci rcu lar or squa re) d istri bution or bisym metrical light distribution patterns. Lum i naires will often have rotatable optics to better optimize l ig ht d istri bution patterns. Luminaires typically are high wattage. n u m ber of roadway u s e r-approach a ng les. The advantage of a flood l i g ht over down l ights is they can be a i med toward dark spots to i m p rove u n iform ity. The d i sadvantage is that they typically emit more g l a re than a h i g h-mast dow n l ight. Floodlights may a lso be m o re obtrusive to l ocal residents and should be used with some caution. Flood l i g hts should have optics with i nternal or external shielding to red uce the g l a re i m pa cts. A s u ccessful des i g n practice has been to use Hig h-mast luminaires are available with a closed or a combination of down l i g hts to l i g ht a round the pole, open bottom . With a c l osed-bottom l u m inaire, a a n d flood l i g hts to better shape the distribution of l i g ht lens is connected to the reflector. An open-bottom to s u it the road g eom etrics. As shown in Figure 6-9, l u m i naire has no lens, and the l ig ht source and reflector a combination of flood l i g hts and down lig hts proved are therefore exposed. The lens in a cl osed-bottom very effective. l u m i naire sea ls the optical system, so a n open-bottom l u m i naire will have better a i rflow withi n the optical system than the closed type. W h e n desi g n i n g with flood l i g hts it is i m porta nt to avoid a i m i n g the l u m i n a i re more than 62 d e g rees a b ove n a d i r to aid in red u c i n g g l a re. H i g h -mast design With a n open l u m inaire, if the spun a l u m i n u m reflector with flood l i g hts s h o u l d be u nd erta ken cautiously a n d is exposed it wi l l be more suscepti ble to rapid oxidation o n l y b y t h o s e experienced i n t h i s m ethod o f desi g n . tha n a closed l u m inaire wou ld. When the reflector It i s a l so i m portant to note that flood l i g hts m a y not oxidizes, it da rkens and efficiency is red uced. An open meet the restrictions of some l i g ht i n g ord i na n ces. l u m i naire should therefore have a protective coating (Refe r to Section 6.2.7 Flood l ighting for m o re applied to the reflector to reduce oxidation and a l low for easy clea ning. H istorica l ly, two coatings have been i nformati o n .) com mon. A thin anodized coating is most common. It i nvolves a n electrochemical process to build a n oxidized layer a few m icrons in thickness t o protect the a l u m in u m su rface from further oxidation. The other method involves the a ppl ication of a thin layer of silicone to the su rface to protect it. However, the silicone is subject to damage by abrasion d u ring cleaning. A closed l u m i naire with a lens will be easy to clean, as the dirt will typically accum u late on the outside of the lens. I n a n open l u m inaire, prismatic g lass should be avoided, as it is very hard to clean. Both open luminaires with a g lass su rface over the reflector and closed l u mi naires Figure 6-9. Example of mixed floodlights and downlights can be effective. within a high-mast installation. (Photo courtesy of WSP) 6-9 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 6.2.4.2 Raise/Lower Systems for High-Mast Lighting. In m i nutes, once the winch d rive unit is installed, to raise high-mast lighting, luminaires are located on a mounting or l ower the l u m inaire ring, depending on the height of ring (typically 3 to 1 2 luminaires). The ring is attached to the pole and the winch d rive ratio. cables that allow the luminaires to be lowered to ground level for servicing. The components for this type of raise/ Al l h i gh-mast lowering systems should have a centering lower system are shown in Figure 6-8 (see Section 6.2.4.1). mechanism inside the ring that keeps the ring sufficiently There a re three main types of raise/lower systems: during operation. centered on the pole to prevent damage to the system • Top-latching units. The l u m inaire ring latches at the top of the pole to hold the ring and l u m i naires • Top-latching, non-latching, and bottom-latching a re a l l in position at the top of the pole. Once the l u m i naire proven systems. The designer specifying t h e hig h-mast ring is latched, the raise/lower cables a re no longer eq u i pment should consult su ppliers for specific prod uct under tension. information. The designer should advise the owner with Non-latching units. The l u minaire ring is suspended respect to the advantages and disadvantages for each by the raise/lower cables under ful l tension, with no type of system . The decision on the high-mast system latch at the top of the pole. The winch is the locking should be made in consu ltation with both the owner device that latches the fixture in place at the top of and the owner's mai ntenance personnel. the pole. It is also com mon for these systems to have a safety chain that manua l ly hooks to the transition plate when it is at the base of the pole. • Bottom-latching units. The su pport cables are detachable and connected to a separate external lowering winch and cable spool at the bottom of the pole, which is used to raise and l ower the ring. 6.2.4.3 High-Mast Obstruction and Warning Devices. High-mast poles may require special considerations for aircraft, including obstruction-warning l ig hts mou nted on the luminaire ring for daytime and nighttime visibility, and sometimes special paint schemes for daytime visibil ity (see Figure 6-10). The designer should consult For all high-mast systems, the supporting cable systems run from the winch up the pole and around a series of pulleys on the masthead, and connect to the luminaire ring. To raise and lower the ring and l u minaires, workers access the winch through a large hand-hole in the pole and operate the winch drive unit to move the luminaires and ring up or down the pole. Most systems use three cables for balance. These cables attach to a transition plate from the top, and a single cable runs from the bottom of the plate to the drum of the winch. Cable size and load capacity should be careful ly selected based on the collective weight of the lowering system and luminaires. While most manufacturers recommend a safety factor of 5:1 for cable load rating to ring and luminaire weight, life safety codes may require a safety factor of 1 0:1 . The winch drive unit can be a portable unit (drill-type device), or each pole may be equipped with an internal motorized d rive u nit. Some suppliers offer systems where l u m inaires ca n be lowered and/or raised by Figure 6-1 0. Painted high-mast poles. remote control from off site. It may take as l ong as 20 (Photo cou rtesy of West Coast Engi neering) 6-1 0 Lighting System Components with federal and local airport authorities and check local 6.2.4.6 bylaws to confirm requirements for these features. Considerations. As noted previously, caution sho u l d H ig h-Mast Roadway Lighting Design 6.2.4.4 High-Mast Lighting Electrical Cabinets. H igh-mast residential areas, or in a reas where poles will affect views b e exercised when u s i n g high-mast l ighting i n u rban installations may require a centrally located freestanding of l ocal residents. A public i nvolvement process should electrical cabinet to contain the service equipment and be considered prior to employing a high-mast system i n metering. An example is shown in Figure 6-1 1 . areas where l ight trespass or views may b e a n issue. This will a l low loca l residents to have thei r concerns heard and addressed, and it m ig ht help the designer identify issues that were u n known or unappreciated. Residents in close proximity to a freeway are typica lly most concerned with g la re from the l u minaires themselves, rather than with spi l l light. External shielding and i nternal louvers are effective ways to reduce light trespass and g l a re for loca l residents; however, issues related to daytime views often can not be mitigated. Lighting bylaws may a lso limit pole heig hts. Hig h-mast l i g hting req u i res a slightly different method of design than other types of roadway l i g hting and is discussed i n more detail i n its own section of Section Figure 6-1 1 . Freestanding service cabinet. 5.4.4 - Perform Lighting Design. (Photo courtesy of Valid Man ufactu ring) I n accordance with clear zone requirements from the 6.2.4.5 Use of High-Mast Poles for Colocation Cellular Antennas. of With the requirement for tall cell phone towers, it makes sense to determine the feasibility of Transportation Association of Canada (TAC)'s Geometric Design Guide for Canadian Roads1 and from the AASHTO Roadside Design Guide,2 h igh-mast poles should be offset from the roadway. If offset req u i rements cannot be met, high-mast poles should be protected with a suitable barrier system to provide protection. combining high-mast lighting with cellular antenna arrays. Due to the high intensity l ig ht em itted from high­ This will reduce the number mast l u m inaire clusters, poles i n close proxim ity to of tall structures required in an bridges and signs may cast sharp shadows onto the area. The addition of cel l u lar roadways. The designer should ana lyze the design for antennas may also be a source these i mpacts and m itigate them by locati ng other light of revenue for the owner. sou rces in a manner that will i ll u m i nate the otherwise Due to the additional weight shadowed a reas. and wind loading of cellular antenna arrays, a more rigid Placement (or offset) of l ight poles is a fu nction of pole shaft than that required speed, traffic vol umes, side sl ope, and horizontal and for high-mast lighting may be vertical a l ig n ments. In all cases, the designer should needed to reduce the deflec­ refer to the clear zone section i n the TAC Geometric cellular antennas. tions at the top of the pole. Design Guide for Canadian Roads1 or in the AASHTO (Photo cou rtesy of West This type of installation is Roadside Design Guide2 to determine the pole offset Coast Engi neering) shown in Figure 6-1 2. needed to accommodate the clear zone. Figure 6-1 2. High­ mast lighting with 6-1 1 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 6.2.5 Wall Mounted Lighting. Luminaires may be It is not always possible to achieve the req u i red l ig ht mounted on wal l structu res to provide i l l u m ination for level s with downward-only optics. Therefore, although an area where the wa l l is in close proxim ity to the a rea the desig ner should consider them first, some situations being l i g hted. may req uire a luminaire with a refractor to ach ieve the req u i red l ighting and un iformity. The l u m i naires may be su rface mou nted to the wal l, or may be mou nted i n a l ocation that is cast into the wa l l Manufactu rers offer wal l mou nted l u m i naries in many itself. Su rface mou nted l uminaires c a n also b e used to styles, colors, wattages, light sou rces, and optics. Both light pedestrian a reas, such as stairs or wal kways. tun nel and decorative applications a re shown in Figure 6-1 3. If wall mou nted l u m inaires a re in areas accessible to the public, they should be desig ned to withstand va nda lism. 6.2.5.1 Wall Mou nted Luminaire Equipment. Wal l mounted l u m i naires a re available i n two main types, those with u plight and those without. The types that have u p l i g ht typica lly consist of reflectors a n d/or refractors and are desig ned to throw the light forward. It is im portant to l im it l u m i naire brightness in order to prevent glare at the typically l ow mounting heig hts of wall luminaires. 6.2.5.2 Design Considerations for Wal l Mou nted Luminaires. Wa l l mou nted l u m i na ries a re typically mou nted to a vertical su rface. The height is dependent upon the structure to which the l u minaire is mou nted. The height of the structure w i l l often determine whether wa l l -mou nted l u m i n a ries w i l l provide the req u i red level of i l l u m i nation and u niform ity. A wal l-mou nted l u m i na i re may be mou nted on a manufactu rer-supplied bracket, on channel, on a back-box, or in a niche. Wal l mou nted l u m inaries are typical ly o n building facades or in tunnels, as shown i n Figure 6-14. These l u minaires a re typica lly available with forward­ throw optics to direct light away from the wa l l . This type of l u m i naire is less prone to prod ucing glare than the type with a prismatic type of refractor. Figu re 6-14. Wall mounted luminaires in a tunnel. (Photo cou rtesy of WSP) Wa l l mou nted l u mi n a i res may also be u sed to com p l ement b o l l a rd or a rea l i g hting on sta i rs or walkways where the l i g hting is required to be very u nobtrusive. (See Chapter 1 1 for more i nformation on des igning wal kway lighting.) When mou nted near to the g round, wa l l mou nted l u m inaires a re easy to service Figure 6-1 3. Typical wall mounted luminaires. a n d are usefu l in areas where access by service vehicles (Photo courtesy of WSP) is l i m ited, but may be susceptible to vandalism. Like 6-1 2 Lighting System Components bollard lighting, l ow-level wall-mounted lighting is not its own l ig hting a rms and l u m i naires on util ity recommended on or adjacent to roadways. poles u nder agreement with the util ity company. 6.2.6 Roadway Lighting on Utility Poles. Lighting owner, the i nstal lation typica lly fa lls u nder the code may be i nsta l led on utility poles that support overhead provisions of the applicable national electrical code. When roadway lighting is insta l led by the roadway distribution or tra nsmission li nes, as an alternative to instal l i n g separate l ig ht poles. A typical installation is shown in Figure 6-15. • Installation by others. Many util ities requ i re the l ig hting desig ner to show load a nd cable tension calculations. 6.2.6.1 Equipment for Roadway Lighting on Utility Poles. Eq u ipment for roadway lighting on utility poles is very s i m i l a r to the equ ipment req u i red for typical davit-style l ighting. The differences are that a separate pole and foundation are not req u i red, and the l u m inaire cantilever arm used needs to be suitable for mounting to the utility pole. (O n rare occasions, decorative lu m i naires are mounted to utility poles.) 6.2.6.2 Design Considerations for Roadway Lighting on Utility Poles. The design and su ita b i l ity of i nsta l l ing roadway l ig hting on util ity poles is based on the spacing Figure 6-1 5. Typical roadway lighting on utility poles. of the utility poles, which is typical ly fixed by the uti l ity company to suit its standard pole spacing for Some uti l ities may prohi bit l ight fixtu res on utility poles. the su pport of overhead wires. It is a lso based on the I n general, roadway l u minaires on utility poles will fa l l uti l ity compa ny's acceptance of lighting on the subject into o n e o f these categories: poles. Not a l l uti l ity poles a re su ita ble for lighting, due • I nstal lation by the utility. Util ity compan ies to strength concerns and the presence of other devices, sometimes offer progra ms where they supply, such as switches and transformers. insta ll, and maintain roadway l ig hting on their poles and bill the owner on a flat rate basis. This is often I nsta l ling l i g hting on util ity poles will not a lways achieve referred to as "lease lighting." Code req u i rements for requ i red l ight levels and uniformity ratios; pole spacing insta l lations by util ities may fal l u nder their "util ity and pole heig hts are defined by the utility, whose status u m brella," which exempts the installation pri mary goal is the efficient distrib ution of power, not from certain provisions of national codes, such roadway lighting. Roadway owners should be a lert to as the U.S. National Electrical Code (N EC) or the the potential for increased l iabil ity if lighting criteria Canadian Electrica l Code (CEC). Typical ly, the utility can not be met. will have adopted its own standards, which may not meet the req u i rements of the code. Th is may create Roadway light fixtu res on utility poles can be used a problem if the utility or m u n i cipality desires to effectively in areas where conventional l i g ht poles transfer the ownership of the l ig hting to a non­ ca n n ot be insta l led due to cleara nce conflicts with uti lity entity. Many utilities instal l outdoor lighting overhead power l ines. that meets the req u i rements of the U.S. National Electrica l Safety Code (N ESC), a lso known as IEEE C2. • I nsta llation Locating luminaires on utility poles, rather than i nsta l l ing a separate light pole, may reduce visual cl utter, reduce by the roadway owner. The ju risdiction that owns the roadway may supply the n u m ber of potential roadside objects, and reduce the potential for overhead power l i ne conflicts. 6-1 3 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 6.2.7 Floodlighting. Flood lighting uses aimable luminaires to direct a beam of light to accent and highlight architectural elements such as statues, monuments, wall features, and similar structures. It may also be considered for some high-mast lighting (see Section 6.2.4). Floodlighting can be used to project light over a long distance onto a specific surface, or to illuminate irregular shapes. It should not be used for conventional roadway lighting (other than high-mast), due to the increase in g lare when compared to conventional roadway luminaires. 6.2.7.1 Equipment for Floodlighting. Figu re 6-1 6. Typical floodlights. Floodlights are designed to project a controlled beam of light onto a surface. Examples of floodlights are shown in Figure 6-16. and horizontal aiming angles can be set by the installer. Floodlights may alternatively be supplied with an aiming device (sight). Proper aiming ensures that the most intense Fl ood lights may be mou nted on a pole or other suitable portion of the floodlight's beam can be directed accurately structu res. Mounting l u m inaires on the g round or in to a specific point on the surface being illuminated. locations accessible to the public should be avoided to reduce the potential for damage due to vandal ism. 6.2.7.2 Design Considerations for Floodlighting. Designing for floodlights is much different from designing Manufacturers offer floodlig hts in a wide variety of for typical roadway l u m i naires. The designer selects styles, colors, wattages, beam types (rang ing from the appropriate NEMA' beam types based on the area na rrow to wide), light sources, and optical systems. being illuminated and the illumination and uniformity requirements. Then, through a "trial and adjustment" When selecti ng a flood l i ght, it is recommended that process, wattages and aiming are refined until the criteria external shields or internal l ouvers be suppl ied with the are met. The use of computer software allows the designer l u m i na i res to reduce offsite spi l l l ight and glare, as wel l to try various combinations quickly in order to arrive at the as to reduce uplight. Photometric data used in lighting optimal design. During construction, the designer should design should i nclude test data that were gathered with verify the aiming points and aiming angles onsite with the shields or louvers in place. the installer. Some good rules of thumb for floodlighting design are shown in Figures 6-1 7a, 6-1 7b, and 6-1 7c. Since floodlights need to be aimed, they should be supplied with a built-in aiming protractor so that vertical • National Electrical Man ufacturers Association (U.S.) P r Illumination 2/3ofArea Area toBe Illuminated Area to Be Illuminated Area to Be Illuminated Figure 6-17a. Floodlighting design considerations. Left: Aiming the luminaire at the far side of the area to be illuminated results in wasted light and unwanted glare. Middle: Aiming the luminaire at the near side of the area to be illuminated results in hot spots on the near side and poor illumination on the far side. Right: A good general rule is to aim the luminaire two thirds of the distance across the area to be illuminated, or two times the mounting height, whichever value is lower. 6-14 Lighting System Components i l l u mination levels can vary g reatly from one floodlight to a n other, even though they have the same NEMA bea m type. This is because each beam type includes a l a rge span of bea m spread a n g l es. As the bea m spread approaches the adjacent N EMA beam type there may be little practical difference between floodlig hts classified in adjacent beam types. Flood lights may be mou nted to wa l l s, on poles, or i n t h e g round. Where flood l ights are mou nted i n locations accessible to the public, they should be vandal resistant. 6.2.8 In-Roadway Lig hts. I n-roadway l i g hts (see Figure 6-1 7b. For visual comfort, the luminaire should Figure 6-18) are inserted into the roadway pavement be aimed at least 30 degrees below horizontal (no more on pai nted center or shoulder lane l ines to deli neate the than 60 degrees above nadir). lanes for i m p roved g u ida nce. This method of lighting is a imed at enhancing the lane l ines g u ida nce system a n d is not i ntended to i l l u m inate the road surface. Luminaire In-roadway l i g hts are a lso inserted i nto crosswal k l i nes and may be used in place of overhead flashers as a sig n a l device . • • IRLs have proven effective in some appl ications, such as delineation of lane l ines and center and shoulder l i nes on a roadway.3 However, in general they have proven Plan View Figure 6-17c. When floodlights are aimed so that less effective as an alternative to overhead signals at crosswa l ks. illumination from adjacent luminaires overlap, acceptable uniformity is usually achieved. The l ig ht distribution of a floodlight is typica l ly described in degrees of beam spread or by N EMA type. A floodlight's beam angle is the width across the beam, measured through the maxi m u m candlepower value and bounded by the angles where the i ntensity is 50% of maxi m u m . Symmetrical flood l i g hts have the s a m e horizontal and vertical beam spread and a re classified with one N EMA n u m ber. Asym metrical bea m spreads have sepa rate horizontal and vertica l desig nations, identified by the l etters H and V. The horizontal (H) va l u e is a lways g iven first. For example, a flood light with beam a n g l e 80 degrees (H) x 60 degrees (V) is a N EMA 5 x 4. The N EMA beam type should only be used as a general Figure 6-1 8. Typical IRL installation. reference. The shape of the l ig ht pattern and pea k (Photo cou rtesy of ITEM Ltd.) 6-15 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 6.2.8.1 Equipment for In-Roadway Lights. In-roadway 6.3 Light Sou rces l i g hts typical ly consist of LEDs clustered together and As noted in Section 2.4 enclosed in a housing that is attached to or inset into many different types of l u mi naires as wel l as a variety the roadway surface. Various technologies are availab le, of l ig ht sources. Cu rrently, the primary l ig ht source for as described in Section 6.2.8.2. - Light Sources, there are existing roadway l i g hting instal lations is l u m i na i res with lamps classified as high i ntensity discharge (H I D). 6.2.8.2 Design Considerations for In-Roadway Lights. In newly insta l l ed roadway lighting systems, LEDs a re In-roadway l ights may be especially useful in locations the most common light sou rce. Other, less common with heavy fog, in tunnels, or as positive g uida nce in light sou rces used for roadway l i g hting appl ications situations using reversible lane systems that do not use include low pressure sod i u m (LPS), compact fluorescent, barriers to separate traffic. The main elements of design for in-roadway l i g hts a re prod uct selection and specifyi ng the spacing between the i n - roadway l i g hts. The U.S. FHWA's Manual on Uniform Traffic Control Devices defines IRL spaci ng, sets their maxi m u m height at 19 m m a bove the roadway su rface, and has req u i rements for flash rate and actuation method. The electrical system can be solar powered, or powered from a standard electrical incandescent, and induction lamps. The main specification for lamps in North America is the American National Standards Institute (ANSI), which lists a specific code to describe the characteristic of a lamp. ANSI specifications are often used to match ballasts to lamps. Concise and general information about l ight sources is provided i n this section. More-detailed information can be found i n ANS/I/ES LP-4-20, Lighting Practice: Electric Light Sources - Properties, Selection, and Specification.4 service via conduit or d i rect burial cable in a pavement saw cut. I n-roadway l ig ht systems should be designed To d etermine the appropriate l ig ht source for a design and insta l led in accordance with the manufactu rer's a p p lication, a n u m ber of factors must be considered, recommendations. including: • I n - roadway l i g hts typica lly req u i re a h i g h l evel of Lu m i nous efficacy: Somet i m es just c a l l ed "efficacy," this is the lumen output divided by the mai ntenance and a short life due to damage from input wattage. It is expressed as "lumens per watt" frequent contact with vehicle tires and snow removal and is a measure of a l ig ht sou rce's efficiency in equi pment. They should not be insta l led in a reas prone prod ucing l i g ht from e lectricity. This is a key factor to snowfa l l . The pavement should be relatively new when selecting a light source. Typically, a higher and in good condition to accept the in-roadway lights. l u m i nous efficacy translates to less energy use, If the road is rutted and cracked or the pavement is which leads to optimized value. in poor condition, i n - roadway lig hts may be more susceptible to being dislodged, damaged, or destroyed. • Light source physical characteristics: 0 Shape (for lamps only): A letter or letters ind icate Repaving the roadway may require reinstal lation of the the bulb shape, and a n u m ber ind icates the i n-roadway light system . As roads a re often repaved approximate bulb diameter. or open trenched to add or service va rious utilities, 0 Maximum overall length (MOL) (for lamps only): the designer should confirm that the pavement w i l l This is the overal l length of the b u l b measured remai n intact and that repaving is not scheduled prior from the top of the bulb to the bottom of the to specifying in-roadway lights. base. 0 Light center length (LCL) (for lamps only): This is In-roadway lights sho u l d not be considered a substitute the d istance from a reference point on a lamp for warranted roadway l ig hting. When assessing this base (usually the eyelet) to the center of the l ig ht type lighting system, the overal l l ife cycle costs should sou rce. For H I D la mps, it is the d istance from the be verified to confirm costs and benefits. center of the a rc tube to the bottom of the base. 6-1 6 Lighting System Components 0 0 Base type (for lamps only): For H I D la mps, bases i nd ustry standard for LED end of l ife is the point are typically screw-in med i u m or mog u l type. The at which light output has reached a percentage lamp base type is req u i red to be com pati ble with of its initial output, usua l ly 70%. This is reported the l u m i naire lamp socket. as the bo value. Operating position (for lamps only): Some H I D ° i ndex is an ind ication of the abil ity of the l ig ht position. If they a re operated in positions other sou rce to render colors, as compared to a than the preferred position, the l u men output reference sou rce of the same correlated color of the lamp is subject to depreciation losses temperature (CCT). The h igher the n u m ber, the known as the tilt factor. The preferred position better the rendering of color. is defined by the orientation of the base in the ° operating position, and can be base up, base light, expressed in kelvins (K). Except near sun rise as u niversal, meaning they may operate in any and sunset, daylight CCT can vary between a bout position. Lam ps with u n iversal operation may still 4600 K and 6500 K. The hig her the va l ue, the req u ire a t i lt factor i n calcu lations, depending on more blue or "cool" the light appears. The lower how the lamp was tested. Lamp manufacturers the val ue, the more yellow or "wa rm" the l ig ht wi l l often test thei r lamps in the optimal operating position to measu re the hig hest l u men output. Tilt factors a re then appl ied i n the l i g hting a ppears. (See Figure 6-1 9.) 0 tu rned off and i mmediately reenergized from operate i n a l l positions. Pu blished lamp data a ful ly energized (hot) state is the restrike time. should be closely scruti nized to determine the This va l ue is i mportant to consider when q u ick operating position and tilt factor. The l u men output of l ig ht sou rces depreciates recovery from power outages is needed. 0 i nto the relevant a mount of radiant power at each known as lamp l u men depreciation and may be corresponding wavelength. expressed as a l u men mai ntenance factor. Lumen output (initial and mean lumens): Light sou rces a re measured by thei r lumen output. Initial l umens a re typica l ly measured at 1 00 hours of use, whereas mean l u mens are measured at 40% of rated l a m p life for fluorescent, compact Spectral power distribution (SPD): The optica l rad iation emitted from the l i g ht source separated over their expected life at d ifferent rates. This is 0 Restrike time: The time it takes for a H I D lamp to reach 90% of l ig ht o utput after it has been calcu lations, even if a l a m p is desig nated to Lumen maintenance (lamp lumen deprecation, LLD): Correlated color temperature (CCT): CCT is a measure of the visual "wa rmth" or "cool ness" of down or horizontal. Lam ps may also be classified 0 Color rendering index (CR!): The color rendering lamps are desig ned t o operate i n a preferred 0 Mortality: Describes expected lamp su rvival rates based on mai ntenance sched u les. For H I D lamps, mortality is expressed in hours of use based on 10 hours of operation per start. However, the length of the "starts" used d uring testing may fl uorescent and MH lamps. Mea n l u mens for H PS 9000 lamps a re measured at 50% of the lamp's rated l ife. For LED sou rces, only the initial l umens are North lightibkJe •ky 7000 Doylight flourescent 6500 used. Cle•r mercury vopor 6000 Rated lamp life: Lamp life will vary for different l ig ht sou rces and, in some cases, is dependent on 5500 High noon LEDs do not typica l ly fail outright but instead continually fade. The Cle•r met>I har� Cool wh' e floultieent 4500 Hologen lomp 3500 3000 LED) sou rces indicates the n u m ber of hours the lamp is expected to b u rn i n relation to median sooo 4000 the lamp wattage. Rated life for traditional (non­ (50%) life expectancy. 8000 7500 referred to; the term "mean l u m e n output" is not 0 8500 SUntise Undle 2500 2000 1500 I .,.,..._ I W.nn white flourescent 'l(NI inandescent High pressure wxlium Figure 6-19. Correlated color temperature chart. 6-17 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities vary as noted in manufacturers' pu blished data. may be found in ANS/I/ES LP-4-20, Lighting Practice: Electric A typical mortal ity c u rve is shown in Figure 6-20. Light Sources - Properties, Selection, and Specification.4 Morta l ity cu rves a re different for each lamp type. 6.3.1 Light Emitting Diode (LED). LEDs are solid-state of Lamps Surviv\ng sem icond uctor devices that convert electrical energy d i rectly into l i g ht. LEDs can be extremely small and a re dura b l e, and they provide longer life than many other light sou rces. A photograph of a typical printed circuit 00 i:: 100 board (PCB) with LEDs with and without individual 90 lensing is shown in Figure 6-21 . :i BO i!:: 70 � � so !J .. 60 'g .. i:: � 0. .. 1i ... 20 10 0 .. .5 30 ... .., 0 4.000 8,000 "' 12.000 Hou c ... 4 16,000 20,000 .000 of Us Figure 6-20. Typical mortality curve with typical maintenance cycles applied. As noted in Section 2.3.4 - Spectral Effects, Research i n the a rea of visibility has recently found d ifferences in the detection distances of objects and pedestrians u nder various CCT l ig ht sou rces. While earlier research using achromatic targets indicated no difference in performance when comparing source color,3 m ore­ Figu re 6-21. LEDs on a PCB with and without lensing. recent reports using the more real istic condition of (Photo cou rtesy of WSP) colored targets ind icate spectrum can p lay a role i n affecting detection distance. W h e n selecting a l ig ht sou rce, i nformation in this chapter sho u l d be read in conj u n ction with Section 1 0.5.2. As a low wattage sou rce, LEDs generate comparatively l ittle heat d u ring operation. Because of this characteristic and the fact that they do not rely on a deteriorating Light sou rce characteristics can be obtai ned from material to generate lig ht, LEDs have a l ong operating manufacturers' websites or suppliers' cata logs. l ifeti me. LED light output is ava ilable in a wide ra nge of When viewing suppliers' l ig ht source information, it choices for outdoor l i g hting. In general, as the light is critica l that prod uct q u a l ifiers and footnotes be output of the luminaire increases, so does the overa l l reviewed closely and a re fu lly u nderstood. This will heat generated b y t h e l u m i naire, which may result in a col o rs; however, CCTs of 3000 K to 4500 K a re popular assist the desig ner i n determi n i n g whether a l i g ht red u ction in LED life u n less the l u m inaire is designed to sou rce is suitable for a g iven application. For example, as shed the heat generated. described a bove, many lamps are orientation sensitive. LED l u m inaires for outdoor lighting started to become Light sou rces a ppropriate for roadway l i g hting a re a viable sol ution around 2005; as such, the technology described in the sections below. Add itional information is sti l l evo lving. However, by 201 3, development had 6-1 8 Lighting System Components stabilized. Lighting manufactu rers have i nvested large amounts of capita l and research into developing new LED products. The transition from suppliers prod ucing H I D-type sou rces to LEDs was very rapid. Product design and quality vary from supplier to supplier, as they each have their own ideas regard ing how to best util ize the LED technology. In roadway lighting applications, LED luminaires' photometric performance continues to evolve, and they now perform as wel l as or better than their HID counterparts. I nitia l ly, LED l u m inaires were very expensive (capital Figure 6-22. Typical HID lamps. cost) when compared to conventional, industry standard l u m i naires. This resulted in a l ow demand. However, Light from H I D lamps is produced by a n a rc d ischarge prices have been dropping rapid ly, making LED systems between two electrodes located at opposite ends of com petitive with H I D a n d other traditiona l -source an a rc tube within the lamp. H I D lamps req u ire bal lasts systems. Beca use of their l ow power cons u m ption, to p rovide the proper cu rrent d uring wa rm-up to fu l l LEDs should especially be considered in applications lu men output. The bal last then provides t h e proper where power is l i m ited, such as solar-powered systems, voltage and cu rrent to maintain satisfactory operation. or where l ig hting is not warranted yet some level of The starter (when required) is located in the ba l last circuit. The lamp and bal last m ust have compatible ANSI i l l u m i nation is desired. designations to ensure proper operation. Adva ntages of LEDs i n cl u d e very l ow powe r consumption, high efficacy, and advertised l ong l ife. An u nsettling stroboscopic effect due to flickering may Disadvantages include sensitivity to heat, electrical occur in H I D l a m ps just prior to lamp fai lure. variations, and unknown l ong-term performa nce. As with all l ig ht sou rces, it is im portant that system g lare The most common H I D light sou rces and their operating be controlled in order to provide a visu a l ly effective cha racteristics are: lighting system . • High pressure sodium (HPS). These lamps produce light by a n electrical d ischarge through sodium 6.3.2 High I ntensity Discharge (HID). A l l types o f H I D va por operating at relatively high pressures and lamps are widely used for roadway l ighting. Common temperatures. In the past, HPS lamps have been HID sou rces are high pressure sod i u m (H PS), and metal very popular in roadway l ighting, and they provide halide (MH). All of these sources req u i re bal lasts for a golden-yellowish color of l ig ht. proper operation. Al l H I D lamps req u i re a wa rm-up period, as wel l as a cool-down period before they can Advantages to H PS lamps include high efficacy, long be re-energ ized (known as "re-striking"). These times life, u niversal burning positions (some nonstandard wil l vary for different lamp types. An example of H I D l a m ps a re position sensitive), a wide ra nge of lamps is shown in Figure 6-22. availa ble wattages, and good lumen maintenance. Restrike is typica lly one min ute or less, and can be The H I D lamp is made up of a socket and a g lass instantaneous with a dual arc tube, i nstant restrike bulb. Within the b u l b is a n arc tube, which encloses lamp. various gases and metal salts, operating at relatively high pressures and tem peratures. The lamp's electrical Disadvantages to H PS lamps include poor color power consumption is specified by wattage, while the rendering (can be im proved with color corrected light output of the lamp is expressed in l u mens. H PS lamps). 6-1 9 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities • Probe-start metal halide (MH). These lamps are 6.3.3 Fluorescent. Fluorescent la mps are ava ilable in a n H I D l ig ht sou rce in which the l ight is prod uced a wide variety of l u men outputs, shapes, and colors, by the radiation from mercury and from hal ides while having desirable characteristics that include good of metals such as sod i u m, sca nd i u m, indium, and to excellent life, l u m inous efficacy, lumen maintena nce, dysprosiu m . Some lamp types may a lso util ize a a n d color renderi ng. phosphor coating. Metal halide is a "white" l ig ht source. A wide variety of MH lamps is ava i lable. MH The fluorescent lamp is a low-pressure gas discharge source has often been the source of choice for applications in which light is produced predominantly by fluorescent where color rendering is of im portance. powders, also known as phosphors, which are activated by ultraviolet (UV) energy generated by a mercury arc. This Advantages of MH lamps i nclude m id range color process is illustrated schematically in Figure 6-23. rendering capa b i l ity, high efficacy, and a wide range of available wattages. , _ Visible radiation _ Ultraviolet radiation Disadvantages of MH lamps include l ong restrike time, l u men depreciation higher than H PS, short life (typically half of H PS life), typical ly orientation Internal ) ·:·:�: \�\ =: ::·.·:.: :. Electrons Phosphor Coating sensitive, color shifting near end of l ife, problematic cold starts, higher lamp cost than H PS, possible Figu re 6-23. Schematic illustration of the process of radiation burns if lamp envelope is broken, and creating optical radiation with a fluorescent lamp. lower efficacy than H PS. • (© I l l um i nating Engi neering Society) Pulse-start metal halide. While probe-start MH All else being equal, higher lumen output requires more la mps use a bimetal switch i nside the lamp to surface area of phosphor and therefore longer tubes. d isconnect the starting e lectrode once the H I D Single-ended fluorescent lamps, such as CFLs, have multiple l a m p is warmed u p, this req u i rement is eliminated shaped tubes joined together to form a continuous arc in the pu lse-start MH models. An igniter del ivers path. This increases the ratio of lumen output to overall size. a h i g h voltage pu lse d i rectly across the lamp's operating electrodes to start the lamp, similar to technology used for H PS lamps. Flu o rescent l a m ps are h i g h ly sensitive to a mbient tem perature. Figure 6-24 i l lustrates lumen output as Ceramic MH la mps (CMH) are a type of pu lse-start 100 MH lamp. Compared to typica l MH lamps, they have better color rendering, higher efficacy, and red uced color sh ift at the end of life. The advantages of pulse-start MH over probe­ start MH l a m ps include m u ch longer l a m p l ife in wattages over 1 50 watts (some la mps may be position sensitive), i m proved l u men mai ntenance, l � � 80 v ; E � E 1i� � � 0.. ['..� -:· � .> 1,/ ,� 1 /: /. ,. 60 u p time, faster restrike time, and colder starting - -- I ." / . 40 I I - !Acti�e power 1 �ffichl _ reduced color shift, i mproved CRI, faster warm­ temperatures. __ ·. 1: " 0 c� v -� V' .·:. , '...:.:.: .. / igh output 20 10• 20° 30° 40° so• 60° Minimum Bulb Wall Temperature !Celsius) The disadvantages of pulse-start MH compared to Figu re 6-24. Lumen output vs. bulb wall temperature: probe-start MH lamps i nclude hig her cost and the typical fluorescent lamp temperature characteristics for fact that the la mps are position sensitive. non-amalgam lamps. (© I l l u m i nating Engi neering Society) 6-20 Lighting System Components a function of b u l b wa l l temperature. The exact shape ()1J, ,------.---.- of the cu rves w i l l depend on the lamp and ballast type; however, a l l non-amalgam fl uorescent lamps have curves of the same general sha pe. A m ercury a m a l g a m may be e m pl oyed to red uce temperature dependence. The amalgam sta b i l izes a nd controls the mercury vapor pressure in the d ischarge, thus keeping it close to its opti mal value as the lamp temperature changes. An amalgam lamp can prod uce more than 90% of its maxi m u m l ig ht output over a wide temperature range, as i llustrated in Figure 6-25. 00 500 600 nanometers (nm) 700 500 600 700 500 600 700 Wuelength A downside is that amalgam lamps can take longer to reach fu l l light output when energized. 1 .0 ....., 0.8 ;; g. ::s 0 , , ,, ,,,,.,...-. ... .... .. ,- " OCFJI. ,-----.-- .. .. , , .. .. '' ,, / 0.6 � "' :::; .. 0.4 � .. .... a: ' .. I ,' I I 0.2 I I I ,. ,, �ma1gam - --'Nonamalaam I I 0 -20· o· 20· 40• 60" OD Wavelength In nanometers (nm) Ambient Temperature (Celsius) Figure 6-25. Comparison of relative light output vs. ambient temperature for two compact fluorescent lamp designs, with and without amalgam. Both are for base­ up operation. (© I l l u m i nating Engi neering Society) Many different white and colored fl uorescent la mps are available, each having its own characteristic spectral power distribution (SPD), exam ples of which are shown in Figure 6-26. Typical correlated color temperature (CCT) and color rendering index (CRI) a re i ncluded for each SPD. Wavelength In nanometers (nm) Advantages of fluorescent lamps include high efficacy, Figu re 6-26. Examples of fluorescent lamp SPDs. long life, good to excel lent color rendering, i nstant Top: CCT 3000 K, CRI 80 to 89. Middle: CCT 3500 K, starting, and a variety of CCTs, wattages, and shapes. CRI 80 to 89. Bottom: CCT 4100 K, CRI 80 to 89. Disadvantages i n c l u d e sensitivity to hot and cold (© I l l um i nating Engi neering Society) a m bient temperatures. 6-21 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 6.3.4 Induction (E). Ind uction lighting is classified as l a m ps, which function at 2.65 MHz and 1 3.56 MHz. The a fluorescent technology, as it utilizes mercury vapor low freq uency m i n i m izes electromagnetic interference to create light. A commonly used system for industrial problems and bal last complexity. Together with the a p p l ications decentral ized consists of an ind u ctive l y cou p l e d power injection, the l ow-fre q uency fluorescent l a m p a n d a high-frequency e l e ctronic operation results in a long-life e lectrodeless fluorescent bal last. Two ferromagnetic ring cores generate an l a m p with high light output and high system efficiency. electric field that generates the d ischarge (see Figure 6-27). I nstead of a n e lectrode at either end of the lamp 6.3.5 Plasma. P lasma to power the discharge, the system uses mag netic l a m ps a re a type of induction. The removal of the electrodes e l i m i nates the e l ectro d e l ess lamp typical fa ilure mode of other fl uorescent lamp types. e n e rg ized by rad io The induction lamp is excited by a radio freq uency freq u e ncy (RF) (RF) magnetic field. In essence, the ind uction lamp is m i c rowave a n electrical transformer with a cl osed-loop discharge This l a m p suffered a or power. serving as a one-t u rn secondary winding cou p led n u mber of practical to ferromagnetic cores whose primary windi ngs are problems and did not excited by a n electronic RF power converter (the bal last). prosper com m erci a lly. The RF power is evenly distributed along the discharge These path. This allows for a low profile geometry that avoids have g ra d u a l ly been the excessive thermal stress near the excitation area that can be typical of other RF la mps with i nternal RF d rives. As a fl uorescent lamp, the ind uction lamp uti l izes the Figure 6-28. Plasma lamp. (Photo cou rtesy of Luxim) problems overcome, and newer plasma been l a m ps have i ntrod uced to the general l i g hting market. P lasma la mps covered same mechanism for light generation as is found i n with phosphor are called external electrode fluorescent conventional fluorescent lamps with electrodes: the lamps (EEFL). The so-ca l led external electrodes a re the ultraviolet (UV) radiation generated by the i nternal conductors provid ing the radio frequency electric field. electrical d ischarge is converted to visible light by the A plasma lamp is shown i n Figure 6-28. rare-earth phosphor coating on the inner wa l l of the g lass envelope. The phosphor determines the color of Plasma lighting architecture consists of two fundamental light produced by the lamp. parts: an emitter, which is a quartz lamp embedded in a The induction system operates at frequencies between generator and micro-controller (see Figure 6-29). resonator; and a driver, which is a solid-state radio frequency 1 00 and 300 kHz, the most common being 250 kHz; this is relatively l ow compared to other RF ind uction A radio freq uency (RF) or m icrowave signal is generated a n d ampl ified by the d river, and is then guided into the cera mic resonator thro u g h a low-loss coaxial cable. The structure of the resonator concentrates the RF field, delivering energy to the fu l ly sea led quartz lamp � . d FROM GIENIERATOR d " UV LIGHT J AMALGAM VISlllfUGHT f:NIERGIZIED COATINCi Figure 6-27. One configuration of an induction lamp. Figure 6-29. Plasma lighting components. (Graphic courtesy of America n Green Technologies) (Photo cou rtesy of Luxim) 6-22 Lighting System Components without electrodes or filaments. A h ighly concentrated Disadva ntages for LPS l a m ps i n c l u d e h i g h l a m p electric field ionizes the gases and vaporizes the hal ides replacement cost, shorter lamp l ife t h a n H PS, larger l a m p in the lamp, creating a plasma state at its center. I nside and luminaire size, l i m ited wattages, minimal control of the back of the lamp, a h i g h ly reflective diffuse material is used to reflect all of this l ight to the front. The result is an i ntense source of white light. light distribution, and very poor color rendering. 6.3.7 I ncandescent. Though not applicable to roadway lighting, incandescent (including halogen) lamps can be used for off-roadway and security l ig hting where a low Advantages include: cost and l ow light output a lternative is needed. Because SmalKable of their instant start and restrike capabil ity, l u m inaires • with i ncandescent sou rces can be tied into a motion Disadvantages incl ude: • Limited nu m ber of suppliers and l u m i na i res available sensor where used for secu rity. H owever, LED l u m inaires have this same advantage, as wel l as l onger life and higher efficacy. • Limited n u m ber of available wattages and voltages • Minimum output threshold; practical usage o n ly at at rated line voltage, the ability to be d i m med from a higher light output 100 percent of light output to zero, availability in many Advantages of i ncandescent lamps include good CRI wattages, low l u m inaire cost, and instant starting and By 201 3, plasma lighting had become widely used. It is a technology that has potential and is worth considering at higher wattages (400 W a nd above). re-striking. Disadvantages i nclude very poor efficacy and short l a m p life. 6.3.6 Low Pressure Sodium (LPS). LPS lamps are not classified as a H I D source. LPS is a gaseous discharge type 6.4 Luminaires of lamp, simi lar in operation to fl uorescent l a m ps. LPS A roadway l u m i na i re (or "light fixture") is typically lamps a re a highly efficacious light source. H owever, their desig ned for use in l ighting long na rrow a reas such as color rendition is very poor (they a re a monochromatic yel low), making them generally unsu itable for roadway lighting because visibility is reduced. LPS lamps are also among the most expensive to insta l l . roadways. Its fu nction is to position and control, both electrically and optically, a light source (as discussed in Section 6.3). The l u m i na i re usually consists of an enclosure conta ining the m o u nting mechanism, the electrical control device (such as a ballast or d river), the electrical connections between the power source LPS lamps may b e most suitable for roadway lighting used a n d the light sou rce, and an optical control system near observatories, as the monochromatic color has less (reflector and/or refractor) desig ned to redirect the impact due to filtering technologies available for research l i g ht output of the l a m p to the su rface req uiring telescopes. Due to its unappealing color (yellow), LPS i l l u m ination. Luminaires may a lso be equ ipped with has been used in public areas where the property owner auxil iary equ ipment such as fusing, photocontrols, and wants illumination where people may loiter. However, because of the lower lumen output and yellowish color, this results in poor facial and color recognition. mon itoring and d i m m i ng devices. Properly designed roadway l u mi na i res w i l l contai n a n appropriate driver or ballast compartment optica l system, and housing. The housing provides protection Advantages for LPS l a m ps include short restrike time, for interna l components from the elements, corrosion, m i n i m a l l a m p l u men depreciation, and h i g h l a m p and vibration. Luminaires specifically designed to meet efficacy (lumens per watt). demands for "zero uplight" (a UO in the BUG rating) a re 6-23 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities also ava ilable. These l u m i naires m i n i m ize sky glow while a n d lighting performance req uirements for hig h-mast still performing their fu nction as a roadway lighting l um i n a i res using H PS lamps. The m i n i m u m req u i rements system . esta b l ished by this standard are based on average i l l u m inance, i l l u m ina nce ratios, rated lamp watts, and Luminaires a re ava i lable i n various confi g u rations. The reference lamp lu mens. most common for roadways a re the tra d itional "cobra­ head" styles. These have typica l ly been the m ost In the U.S., l u m inaires and l a m ps should conform to efficient providers of l i g ht on roadways, and ca n be the appl icable docu ments contai ned within the ANSI the most cost effective solution. Where a rchitect u ra l C 1 36 Series.8 These a re product-related documents styles a re req u i red, various h o u s i n g s h a p e s a nd that can be sourced on the ANSI website. (For more styles a re ava ilable. These can be provided with h i g h information on ANSI, refer to Section 7.3 - North performa nce o ptics t h a t com pa re favo ra bly with American Standards Organizations.) the traditiona l cobra-heads, but u s u a l ly at a h i g he r cost. Man ufacturers o f roadway l u m inaires provide Lu m i naires insta l led in areas susceptible to vibration, extensive data sheets and photometric files for use by such as bridges and tunnels, should be desig ned to l i g hting desig ners. meet the requ i rements of ANSI C 1 36.31 .9 Luminaires in a reas with vibration should also be equi pped with 6 .4.1 Luminaire Photometric Performa nce. suitable seismic restraints connected between the Photometric performance will vary from l u m i naire to l u m i naire and the pole or mounting su rface to prevent l u m i naire due to fixture design variations. The lighting the l u m i na i re from fa l l i n g . Lu m i na i res i nsta l led i n designer should obtai n the man ufacturer's I ES-format outdoor environments are subject t o water a n d d ust photometric files for the various products being infiltration; therefore, ANSI C 1 36.25 should be ad hered considered. The designer can use the photometric to for outdoor l i g hting equi pment.1 0 file to compare produ cts as well as u n dertake l i g hting desig n a n d cal c u lations. (Refer to Section In Mexico, roadway l ig hting and l u m inaires are covered 2.5 by the Manual de Jluminaci6n Via/.11 - Measurements and Chapter 8 - Computer Appl ications for m ore i nformation on photometry and l ighting design.) For LEDs, the I ES has developed Using products meeting the appropriate performance a method for the photometric measurement of sol id­ sta ndards w i l l ensure that l u m i na i res meet known state lighting prod ucts, ANSI/JES LM-79-19, Approved performa nce criteria. Lighting designers are encouraged Method: Optical and Photometric Measurements of So/id­ to seek out and use products that meet the performance State Lighting Products. 5 req u i rements. 6.4.2 Special Luminaires. Considerations for Roadway 6.4.3 Alternative Power Sources. For a reas where In Canada, Photometric Performance access to power may be l i m ited, alternative power of Roadway and Street Lighting Luminaires (CAN/CSA sou rces w i l l be needed . Some known a lternative power C653)6 provides energy and l i g hti ng performance sou rces include solar and wind power. requirements for roadway l u m i na i res using H PS and MH lamps. The standard applies to l u m i naires using small Solar power solutions are offered by many suppl iers. and medium refractors made of material such as glass, Solar systems can be self-contained electrical systems polycarbonate, or acrylic. This standard is based on req u i ring no external power su pply. Solar panels charge average l u minance, luminance ratio, rated lamp watts, the system's batteries d u ring daylight hours, and the and rated lamp l umens. batteries power the l u m i naires when lighting is needed . A photocontrol (or other timing eq u i pment) may be For hig h-mast l ighting, the Canadian standard CAN/ used to turn the lig hts on at dark and off at dayl ight, CSA - C81 1 , Performance of Highmast Luminaires for similar to standard lighting systems. Typical ly, solar­ Roadway Lighting (CAN/CSA C81 1 ),7 provides energy powered systems utilize an LED, low-voltage CFL, or LPS 6-24 Lighting System Components light source to reduce the power consumption in order fac i l itate maintenance activities. This is referred to as to m i n i m ize the size of the solar panels and the size "tool-less entry." and/or nu m ber of batteries required, thereby red ucing the overa l l cost. Due to solar panel and battery size and Special consideration of the housing is necessary for potential related costs, l u m inaire l ight output may be L E D l u minaires, as the housing is necessary to the l i m ited. dissi pation of the heat prod uced by the LEDs. Wel l ­ designed currently ava i l a ble l u m i naire prod ucts w i l l Wind power, though not as common as solar, may be have a housing that c a n a c t as a heatsink t o dissi pate considered. However, research is req uired to determine a n d m i n i m ize heat buildup, which wi l l g reatly affect the if the location proposed will be suitable for a long­ life of the LED and driver i nternal components. term i nsta l lation. This would include studying wind maps, weather patterns, and l ongevity of a potential 6.5.2 LED System Components. installation, among other considerations. 6.5.2.1 Light Engine. Regardless of the alternative power source utilized, it is important that the designer be cognizant of the nu mber of days the system can susta in itself without the a lternative energy sou rce. There is cu rrently no g u ida nce for req u i rements for a lternative energy self­ autonomy, however, approval should be g ranted from the road authority. The LED l i g ht engine is an assembly composed of LEDs mou nted on a pri nted circuit board (PCB) typica l l y made of a l u m i n u m . 6.5.2.2 Optical System. With LEDs, man ufacturers are much better able to control the light distribution and as a result offer a very broad choice in optical systems. LED l u m inaires employ a n u m ber of small point sources of l ig ht. This a l lows for fa r greater optical efficiency than can be ach ieved with traditional high intensity 6.5 Luminaire Components 6.5.1 Housings. to s u pport, discharge sou rces, which utilize large lamps. The small L u m i n a i re housings a re desig ned protect, house, and u n ite all the i nternal components of a l u m i n a i re. Housings may be constructed of steel, a l u m i n u m, zinc, polymer, thermosetting composite, or other similar corrosion resistant materials. Where a specific color is required for aesthetic pu rposes, the housing should be powder­ coated to ensure durabil ity of the fin ish. Composite or polymer housings may have color molded i nto the light sou rces enable excellent beam control with a high level of l ig ht beam efficiency. A very com mon optica l system for LEDs is a n arrangement of many L E D chips (or d ies), each with its own lens system design for various l ig ht distributions. The advantag e of this system is enhanced optica l efficiency. The disadvantage is that the LEDs a re more visi ble and can appear g la ry when viewed from some angles. This kind of optical system is shown in the material. close-up images of Figure 6-30. Some of the individual As a m i n i m u m, the l u minaire optical system should optical systems have lenses with odd sha pes that might meet a n I n g ress Projection rating of I P65. (Refer to be d ifficult to clean. Thus, the ability to easily clean the Annex I LEDs should be factored into the l u m i naire assessment. - Environmental Ratings for Enclosures for a d iscussion of Ingress Protection [IP] ratings.) Most l u m i na i re optical systems are available with an I P65 Another option is to array g roups of LED chips with a rating. The benefit of a l u m i n a i re with an I P65 rating is reflector and util ize the reflector to distribute the l i g ht. that the optical system is sea led from dust and water The LED chips are recessed behind the lens. This type (i.e., rain) intrusion. of optical system is typically less efficient. H owever, because it im proves the d irect-view cutoff angle to the Door latches on housings should be designed to a l l ow LEDs, it u ltimately can reduce glare. This optical system entry to the internal spaces without special tools, to is shown in the right-hand image of Figure 6-30. 6-25 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Figure 6-30. Examples of LED optical systems. (Photos cou rtesy of: GE and Cooper Lighting) Another type of optical system utilizes a large lens the power su pply (line) and the LED (load). The d river over the entire system. The lens distributes the light in converts AC power to a DC power to energize the LEDs. a particular pattern, and it obscures the views of the It a lso filters, reg u lates and corrects the power factor. i ndivid u a l LEDs, which can aid i n reducing glare. It is recommended that the use of polycarbonate and acryl ic materia ls that are d i rectly exposed to s u n l ight be carefully considered, as cu rrently ava i lable products (Refer to Figure 6-32.) A d river is selected by input voltage and d rive cu rrent ratings. Drive currents ra nge from 280 to 1 ,500 mA. The w i l l d isco l o r and become brittle d u e to exposu re higher the d rive current, the higher the light output. to ultraviolet radiation d u ring the day and the heat However, if the LEDs are driven by an a bove-nominal generated by operation. (above-rated) current, their l ifespan may be shortened. The selection of the d rive cu rrent is, therefore, a trade­ Because of the demand to reduce light trespass, many off between optical performance and a nticipated l ife. LED luminaires have photometric distributions that are designed to reduce light behind the luminaire. With the superior optical control offered by the LED optics, sharp cutoff can be achieved behind the luminaire, potential ly making it difficult to properly light the sidewalk. This was Drivers sho u l d include the capability of d i m ming. Two prevalent d i m m ing technologies include 0-1 0 voe and DALI (Digital Addressable Lighting I nterface). A 0-1 0 VDC not an issue in the past for sidewalks with low and medium d i m m i ng system controls the l ig ht output accord ing pedestrian activity levels, as sidewalk illumination and to the one-way analog voltage signal in the nominal uniformity was achieved by unavoidable backlight from the ran g e of 0 to 10 volts DC over a pair of l ow-voltage HID luminaire. To provide the required sidewalk illumination pola rized wires to the driver. DALI is a bidirectional non­ and uniformity, luminaires with optics that provide a level proprietary lighting control protocol . A DALI dimming of backlight should be considered, and lighting calculations system controls the light output according to d igital should be performed to verify that sidewalk lighting criteria are achieved. Supplementary lighting may be required for areas with high pedestrian activity. d i m m ing com mands over a pa i r of com m u n ication wires to the d river. (Refer to Section 6.10 Systems for additional i nformation.) Lighting applications such as isolated rural intersections can benefit from l u minaires with optica l systems that can be viewed from a distance. This is because they can mark an i ntersection as a point of hazard to the d river from a distance. (Note: When a l u m i naire is seen from a long distance, the viewing angle is very nea rly horizontal, and very low-brightness optical systems may be difficult to d iscern.) 6.5.2.3 Driver (Power Supply). The d river is an electronic device that provides a n interface between 6-26 Figure 6-32. Driver circuit. (© I l l um i nating Engi neering Society) - Control Lighting System Components 6.5.3 H I D and Fluorescent System Components harmon ics as compared with the a m p l itude of the fu ndamental freq uency. Harmonic d istortion is the 6.5.3.1 Ballast. The purpose of the bal last is to provide a mount of distortion that the lamp bal last causes the proper starting and operating voltage and current in the power waveform. Typica l ly, it should be less to initiate and sustain the arc discharge between the than 20 percent. (See Section 6.6.5.2 for additional electrodes of the lamp. Electric discharge lamps have a information on TH D.) negative-resistance characteristic. If operated directly from l i n e voltage, this wou ld cause them to d raw Bal lasts a re typica l l y either mag netic or el ectronic. excessive current, leading to instant lamp destruction. Mag netic bal lasts a re the type most commonly used for The ballast is therefore utilized to limit this current to the roadway l ig hting applications. correct level required for proper operation of the lamp. The information noted above can vary for different Ballasts play a critical role in the operation of H I D and products and sho u l d be analyzed when selecti ng a fluorescent la mps and in the lamps' performance. l u m i naire and underta king a desi g n . This information is typical ly available thro u g h the l u m inaire manufacturer Ballasts may differ with respect to energy efficiency, the or d irectly from the bal last manufactu rer. amount of distortion they cause in the power waveform (harmonic distortion), and the amount of light a lamp Street l u m i naires should be g rounded in accordance produces when operated on a specific bal last. The with the a pplicable electrical code. This wi l l req u i re a primary techn ical characteristics by which bal lasts are mag netic bal last with an isolated seconda ry, such as a measured and compared i nclude: constant wattage iso-lead (CWI) or a mag-reg bal last. • • Ballast factor (BF): For information on ballast factor, the reader is referred to the d iscussion on 6.5.3.2 Capacitor. The capacitor works with the bal last, bal lasts i n Section 3.1 .6 - Light Loss Factors (LLF). i m p roving the power factor so that the ballast can Power factor (PF): PF is a m easure of the relationshi p between the AC source voltage and current, and determines the a m o u nt of cu rrent required by the bal last. High-PF ballasts req uire less AC cu rrent to provide optim u m lighting, as compared to an equ iva lent low-PF ba l last. High­ PF bal lasts wil l have a PF g reater than 90%. Use of ballasts with a power factor below 90% should be avoided, as util ity companies may a pply a pre m i u m where t h e PF is below 90%. (See Section 6.6.5.1 for additional information on power factor.) • Crest factor (CF): CF is a ratio of peak lamp cu rrent to the root-mea n-sq uare (approximately average) util i ze energy more efficiently. If a capacitor is not uti l i zed, then the lamp starting current will be higher than the operating cu rrent. Alternating current (AC) and direct current (DC) fil m capacitors are necessary parts o f any H I D ballasting system. Only linear-type ballasts can function without capacitors. 6.5.3.3 Igniter. An igniter (also referred to as a starter) provides a short-duration hig h-voltage pu lse, required to start certain types of H I D lamps. An ignitor is typically requ i red for H PS and pulse-start MH lamps. l g niters are usually designed to American National Standa rds I nstitute (ANSI) specifications. lamp cu rrent. Current crest factor ranges from 1 .0 to i nfinity. A cu rrent with a high crest factor can l g n iters should be designed to prevent the lamp from cause excessive erosion of the lamp electrodes, a cycling on and off when the lamp has failed or a shorted condition that reduces lamp life. Lamp crest factors circuit is present, in order to prevent damage to other are typically 1 .8 or less for meta l halide and high com ponents. lgn itors with a plug-in interface should be pressure sod ium, and 1 .6 or l ess for low pressure considered, as they a re easier to replace when they fai l . sod i u m . • Total harmonic distortion (THO): T H D is a 6.5.3.4 Reflector. A reflector h a s a specular or sem i­ measure of the mag nitude of voltage and cu rrent specular surface, and houses the lamp its socket. Its 6-27 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities purpose is to distribute the l umens out of the l uminaire thro u g h wiring connected to a n electric power grid. by reflection in a manner consistent with the l u m inaire's The connection from the utility grid sou rce is throug h designated classification. In the case of H PS l u minaires, a n e lectrical service, or may b e directly from the l ow the design of the reflector may l i mit the voltage rise voltage secondary. to below ANSI l i m its by reducing the a mo u nt of l ig ht In the case where existing infrastructu re is being relocated reflected back i nto the a rc tube. or rehabilitated, an assessment of the condition, state Reflectors are prod uced from a variety of materials in and functionality of the electrical system should be various shapes and fi nishes. Manufacturers may patent performed. If, due to age, wear and tear, or alteration, the featu res or the appl ication of reflector technology to equipment or wiring has become a hazard, it is required gain a marketing advantage. that all such equipment be removed and replaced. Any replacements or upgrades shal l follow the standards of 6.5.3.5 Refractor or Lens. A luminaire may have a the national or local codes, as applicable. refractor, sometimes cal led a lens, connected to the housing. Refractors can be g lass, polycarbonate, or acrylic In the case where new construction will expand an and are designed to distribute light in a designated existing l ighting system, a n assessment of the cond ition, pattern. The shape of the refractor and the design of its state and fu nctiona l ity of the combined system should prisms determine the light distribution pattern. be performed. The lighting desig ner should determ ine the suitab i lity, condition, and capacity of the existing 6.5.3.6 Lamp Socket. Lam p sockets are typically designed wiring, distribution equ ipment, and loads for expa nsion, to meet a minimum pulse of 4 kV or 5 kV, and are rated as wel l as its compatibil ity with the expanded system. and designed to meet or exceed ANSI specifications. With the exception of LPS, linear fl uorescent, and MH sou rces, The designer should provide recommendations with lamp sockets usually have a medium or mogul type base cap ital cost and life cycle cost estimates (see Section 5.5) for provid ing the new l ig hting system on its own to suit the type of lamp intended for the luminaire. and in combination with bringing the existing lighting system u p to cu rrent standards. 6.6 Electrical Distribution Lighting controls typical ly turn the light on at or near 6.6.1 Electrical System Components. The electrical dark and off at or nea r daybreak. With the exception of portion of a lighting system is typically composed of a the a lternative power sources noted in Section 6.4.3, a l l power supply, utility metering, power distribution cabinet, l ighting is typical ly fed from a n electrica l power supply lighting controls, wiring and luminaires (see Figure 6-33). Utility Transformer � @ @ @ -r�i�1ii ------.M�-11------!--*+-- � _ ----'- J_ J_ h ...... .-.... .....1 ,___ � ___ System with Single Photo Contrell Utility Transformer @ @ @ -{I::!--lH\IHl-- �-+--l � of---r----+---- :r -----'--- :r -'-- � System with I nd iv i d u al Photo Contro l Figure 6-33. Electrical system overview. 6-28 � @ � []�] � Photo Control Luminaire Conduit & Wiring Power Distribution Cabinet Utility Transformer (Point of Service) Utility Meter (Optional) Lighting System Components 6.6.2 Power Supply. E l ectrica l util ity compan ies distribute power throughout a com mu nity by way of underg round a nd/or overhead primary systems at high voltages. The electrical power is then transformed to a suitable useful voltage by a uti l ity transformer at the point of service. Uti l ity transformers may be mou nted on poles, located on concrete pads, or contained in underg round va u lts. Exa mples of util ity transformers are shown in Figures 6-34 and 6-35. Power for the roadway lig hting system is fed from the util ity tra nsformer (or point of service) to a power distribution cabi net. Services may be single-phase or 3-phase. The most common type of service for roadway l ig hting systems is the 1 20/240-volt, single-phase 3-wire service. Other Figu re 6-35. Typical pole-mounted transformer. common voltages and service types incl ude: • 240-volt, single-phase, 2-wire • 480-volt, single-phase, 2-wire l i g hting in the a rea a n d i s set by the owner for • 240/480-volt, singl e-phase, 3-wire sta n d a rd ization pu rposes (e.g., pa rts, m a i ntena n ce, • 1 20/208-volt, 3-phase, 4-wire voltag e s h o u l d match the voltage of oth er street or tem pora ry overhead wiring from one system to a n other.) Exce ptions a p p ly, b u t the d ifference i n • 240-volt, 3-phase, 3-wire • 277/480-volt, 3-phase, 4-wire • 347/600-volt, 3-phase, 4-wi re u n l ess a h i g h e r voltag e is req u i red due to excessive • 480-volt, 3-phase, 3-wire branch circ u i t lengths. Tu n n e l and h i g h- mast l ighting • 600-volt, 3-phase, 3-wire syste m s wi l l req u i re 277/480-volt or 347/600-volt c o s t is genera l l y low compared t o the overa l l project costs. Typ i c a l ly, a 1 20/240-vo lt service wou l d be used services to meet h i g h loads. H i g her voltages a l l ow the desi g n er to reduce bra nch circuit w i r i n g sizes for l o n g c i rcuits. The designer will typical ly calcu late the service size req u i red (e.g., 60 A, 1 00 A) for both the con nected and future loads and coord inate this with the utility provider so they can properly size the utility transformer. Util ity transformers a re suppl ied i n various sizes (kil ovolt­ am ps, kVA) and in va rious voltages. The designer should coordi nate the service location and voltage with the uti l ity provider in order to provide the owner with the best-va lue solution. Utility req u i rements and sta ndards will vary for each Figure 6-34. Typical pad-mount transformer. provider. The owner will typica l ly be req u i red to establ ish an account for the service location with the In the case of a n ew electrical service, the desig ner shou ld c o m p a re costs by c o n s u l t i n g with uti l ity provider for b i l l i ng pu rposes. the uti l ity provider a n d basing the com pa rison on the 6.6.3 Metering. Electricity consumption for roadway va rious vo ltage supply options ava i l a b le. Service lighting can be metered or unmetered (i.e., a flat rate). 6-29 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Uti l ity providers someti mes use revenue meters to 6.6.4 Power Distri bution Cabinets. measure the power consu m ption and, i n turn, bill distri bution cabi net for roadway l i g hting systems the owner of the roadway l i g hting system. Where conta ins overcurrent devices to protect the branch The power meters a re req u i red, they a re typica l ly i nsta l led at circuit wiring. It provides a safe means to d isconnect the power d istri bution cabinet in accordance with the power for servicing activities. The overcurrent protection individ u a l util ity company standards. The meter m ust devices are circuit breakers (or fuses) located in a panel be accessi ble to meter-read i n g personnel, who record board within the cabi net. consu m ption. Some utilities do not req u i re meters and b i l l the cl ient at a fixed flat rate per streetlight. The conductor sizes and l oads and the maxi m u m overcurrent protection rating should b e determ ined A typical reve n u e m eter a rrangement is shown in (ca l c u lated) per the latest edition of the applicable Fig ure 6-36. It is i m porta nt to note that e lectricity electrical code. con s u m pt i o n for n o n - m etered syste m s can be com puted using the connected l oad of a l l l u m i na i res Typically, the m i n i m u m n u m ber of circuit breaker panel i n the system, m u l t i p l ied by the average burn h o u rs board positions is dependent on the num ber and size for each month. of the loads being supplied. The power distribution I n a n etworked l ighting control system, reve n u e ­ as a standalone cabinet. It is recommended the cabinet cabinet may be pole mou nted or i nstal led on its own g rade m eteri ng capacity m a y be b u i l t i nto a control have a m i n i m u m N EMA 3R rating, and a lockable door node or a d river to measure the energy con s u m ption to prevent unauthorized entry. Lighting controls, such of each l i g ht point. I n d ividual energy measu rements as contactors and test switches, are typica l ly located a re agg regated at the centra l management system to in this cabinet also. The util ity revenue meter may be obta i n the overa l l energy cons u m ption of the system. located in this cabi net if acceptable to the uti l ity. Where This will e l i m i nate the need of a sepa rate revenue metering is l ocated within the cabi net, the cabinet is meter i nsta l lation. (Refer to Section 6.1 0 Control typica l ly a pad-mount unit. Systems for m ore i nformation.) Because distribution cabinets may be located in public a reas with aesthetic concerns, designers may be Optional Window Revenue Meter asked to use creativity i n incorporating them i nto the infrastructure. An example of such a sol ution is shown in Figure 6-37, where the designer located the panel withi n a typical piece of street furniture. Other more typical d istribution panels a re shown i n Figure 6-38. Figure 6-36. Example of a utility revenue meter base in a Figu re 6-37. Distribution cabinet located in a trash power distribution cabinet. receptacle. (Photos courtesy of Va lid Manufacturing) 6-30 Lighting System Components A power factor may be affected by dim ming. Therefore, it is necessary for the power factor to be measured by the manufacturer at ful l and dim med l ight outputs. 6.6.5.2 Total Harmonic Distortion (THD). Harmonic distortion is caused by a non-linear load connected to an AC sou rce. Moreover, harmonic d istortion occurs when the load d raws a cu rrent that does not resemble a true sinusoid, l i ke that of the input voltage. In the case of electronics with AC-to-DC power su pplies that util ize a rectifier bridge and capacitor, the cu rrent is only d rawn in the portion of the voltage cycle where the voltage Figure 6-38. Typical service cabinets. reaches a pea k va lue (a positive or negative peak). (Photos courtesy of Va lid Man ufacturing) 6.6.5 Power Quality Considerations. Because a wire will not experience a voltage d rop when Key power q u a l ity considerations i n c l u d e power factor, total harmonic distortion, electromagnetic i nterference, a nd reliability. Each is discussed in the sections that fol l ow. there is no current flow, this spike in current w i l l cause the supply voltage to experience a voltage d rop near the peak va l ues. This voltage d rop causes the supply voltage to flatten near the peaks, causing the input sinusoid to no longer resemble a perfect sinusoid. When harmonic distortion is present in 3-phase systems, it 6.6.5.1 Power Factor (PF). When con nected to a n can be found that, for a perfectly balanced system, A C supply, electrical e q u i pment conta i n i ng reactive there will be a current in the neutral. This is, however, elements (such as capacitors and inductors) wi l l d raw not normal for l i near loads; there should be no cu rrent cu rrent that is not i n phase with the applied voltage. when l oads are balanced. The harmonic cu rrent can be A purely resistive l oad w i l l draw current that is exactly broken down further i nto sinusoids with frequencies in phase with the line voltage at a n ideal power factor that are integer mu ltiples of the fundamenta l (i.e., 60 of 1 .0, or 1 00% (where power factor is a ratio of power Hz) voltage. Tota l harmonic distortion is the sum of each utilized to power del ivered). Where reactive elements harmon ic's squared RMS voltage d ivided by the squared are incl uded in a circuit, the load d raws the additional RMS voltage of the fu ndamental (i.e., 60 Hz) voltage. reactive cu rrent. This cu rrent is rarely utilized by the end-user, and it is d ifficult to measure and therefore d ifficult to col l ect revenue from. Essential ly, this reactive power w i l l cause the delivered power to be larger than the power req uired by the end device. This can cause the utility's i nfrastructure to operate at or above capacity u n necessarily. For example, in order for the utility to su pply power to operate a SO-watt, SO% PF device, it m ust generate and transmit 1 00VA of apparent power. Conversely, if the SO-watt device has a power factor of 1 00%, the utility m ust generate and transmit SO VA TH D may be impacted by dimming and should be measured by the manufacturer at full and dimmed outputs. The TH D req u i rements shall conform to ANSI C82.772002 and be less than 20% at fu l l input power for the fu l l voltage range. 6.6.5.3 Electromagnetic I nterference (EMI). EMI is caused by em ission i n the radio spectrum by electronics such as those in LED d rivers, wire routing, and open and used wires from the d rivers. EMI can i nterfere with of apparent power. To compensate for the i ncreased radio signals as wel l as other electronics. The presence generation and transm ission costs necessary to power or a bsence of EMI should be confirmed by testing the l ow-PF devices, uti l ities w i l l often a pply surcharges entire assem bled l u m i naire, not just single components. to a customer's bill until their power factor has been corrected. Typical ly, uti l ities will now a pply surcharges EMI should meet or exceed e mission standards defined for a power factor lower than 90%. in IEC EN 61 000-6-3. 6-31 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 6.7 Wiring code manual to determine the cable or wire diameter Branch circuit wmng is req u i red from the power and resistance for calculating cond uit fil l and voltage d istribution cabinet to the luminaires. Wiring for street d rop, and to determine the a llowable a mpacity. l ighting can be i nsta l led overhead (strung from pole to pole), but is more typica lly i nsta l led underground. 6.7.2 Overcurrent Protection . Al l wiring circu its a re Overhead wiring is typically reserved for temporary req u i red by code to be protected with overcurrent conditions and is not suitable for poles on breakaway devices such as circuit breakers or fuses, which a re bases, as it is a significant safety issue. located in the lighting d istribution cabi net. In addition, l u m i na i re circuits should be protected with a n i n - l i ne The typical wiring method for street lighting is "daisy­ fuse or terminal b lock located within the pole hand­ chained" para llel branch circuits using the pole hand­ hole (or when a pole is not used, in the nearest junction holes as spl ice poi nts. Figure 6-39 i l lustrates the box or l u minaire). concept. An electrical engineer may determine that wire sizes are to be stepped down as the distance from the 6.7.3 Voltage Drop and Fault Current Calculations. service increases, because the capacity req uirements of Voltage drop calcu lations are needed to verify that the the wiring decrease. All electrica l design sho u ld meet max i m u m a l l owable voltage d rops (per code) have not the req u i rements of the National Electrical Code (U.S.; been exceeded. N EC),12 the Norma Oficial Mexicano NOM-001-SEOE-2012 the Voltage d rop is calculated using Ohm's law. Proced u res Canadian Electrical Code Book (CEC), 14 or as determined used for calcu lating voltage drop vary depending on lnstalaciones Electricas, Utilizaci6n (Mexico), 13 whether the circuit is phase-to-neutral or phase-to­ by the local j u risdiction. phase. Various means are available to calcu late voltage Wiring (Typ.) Pole or Junction Box (Typ.) d rop, including hand calculations and computerized programs that have been designed specifical ly for this purpose. Circuit When calcu lating voltage d rop, the designer should refer Orcu it to the applicable electrical code or util ize appropriate Neutral software for the appl ication. The actual fixture VA Bond (ava ilable from manufactu rer's published data) should be used, as opposed to lamp wattage. Fuse (Typ.) Pole Hand hole Fault current calcu lations may be req u i red to determ ine the a ppropriate i nterrupting capacity of the circuit brea ker, contactors and panel boards. Figure 6-39. Typical 120/240-volt luminaire branch circuit wiring. 6.7.4 Grounding and Bonding. In non-uti l ity a p p l i cations, which are req u i red to conform to the N EC (U.S.) or the CEC (Canada), a l l meta l l i c equipment 6.7.1 Typical Conductor Types. Conductors should be i nsta l led i n a roadway l i g hting system must be stra nded copper or a l u m i n u m with suitable i nsulation. con n ected to a common bonding cond uctor, which Conductor type i s determined by code specifics. should tie i nto the service panel g round. Cond uctors a re typically selected by American Wire Gauge (AWG) size, a U.S. standard set of conductor sizes The main service should be g rou nded in accordance for nonferrous wire. AWG defines a cond uctor size (the with the e lectrical code. Proper grounding depends smaller the n u mber, the larger the conductor), which on a num ber of variables, including soil conductivity, can then be referenced i n the appropriate e l ectrical g ro u n d i ng e q u i pment, and other factors. U n g rounded 6-32 Lighting System Components l u m i naires can pose a shock hazard if there is an internal In-ground junction boxes are typical ly plastic, concrete, short or ballast fa i l u re. or fiber-reinforced concrete. They a re ava ilable in various sizes and shapes (typica lly round or rectangular). They 6.7.5 Conduit. Cond u it for roadway l i g hting is i nsta l led sho u l d have an open bottom and be placed on a brick underground, connecting the l i g hting panel to the base to a llow for d rainage. In-ground j u n ction boxes l u m i naires. It is typica lly i nsta l led i n a trench, as shown should be located in areas outside of the traveled in Figure 6-40. portion of the roadway, where the junction box can be safely accessed by instal lers and mai ntenance personnel. The designer should avoid making electrical connections within in-ground junction boxes. 6.8 Foundations Foundations (also referred to as "bases") are req uired to support structures such as lighting poles. Foundations Figure 6-40. Typical conduit in trench. should be designed to the applicable codes for a given area. In the United States, the AASHTO LRFD Specifications for Structural Supports for Highway Signs, Luminaires, I n-ground condu its are typically manufactured from and Traffic Signals should be followed.15 In Canada, the polyvinyl c h l oride (PVC), which is available in various predominant design code for foundations is CAN/CSA­ diameters and wa l l thickness. It should be noted that C6, Canadian Highway Sign Bridge Design Code.16 direct-bury cable is ava i l a ble. Conduit mounted on or a bove the surface should be ga lvanized rigid steel, PVC, or fi ber-reinforced for additional mechanical protection. 6.7.6 Junction Boxes. Where m u ltiple conduits converge, a junction box is typical ly required to connect the conduits. Junction boxes may be required in-ground and attached to a surface, may be cast into concrete structures, or may be cast into concrete or asphalt surfaces. Typical junction boxes are shown in Figure 6-41. The fou ndation design for poles is typically based on the base reaction forces of the pole as well as the condition of the soils around the fou ndation. A road authority will typical ly have specific standard fou ndation designs based on known soi l conditions and pole load ing. It is the desig ner's responsibil ity to confirm the su itabil ity of standard fou ndation designs for each situation. There are typica lly th ree types of pole foundations used with roadway l i g hting: • Concrete (cast-in-place and precast) • Screw-in a nchor base • Direct-burial pole Each type of fou ndation has a recom m ended use with i n restricted para meters. The l i g hting designer needs to determine which base w i l l be used for each particu lar project. Specialty bases, such as those that a re Figure 6-41 . Typical junction boxes, including pole­ mounted (left), plastic (center), and concrete (right). formed as an i ntegral part of a bridge, req u i re individ ual engi neering design to address items such as pole size, (Plastic j u nction box photo courtesy of West Coast load ing and a nchor bolt arrangement. Listed below a re Engi neering; concrete j unction box photo courtesy of AE genera l g u idel ines for using fou ndations in a variety of Concrete Precast Products) soil conditions. 6-33 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 6.8.1 Concrete Foundations. Concrete foundations Cast-in-place concrete fou ndations a re often used for may be precast or cast-in-place, as shown in Figure 6-42. larger bases that cannot be precast and transported A hole is typically excavated via a backhoe, hydrovac, or from offsite due to weight. They are beneficial when auger, and the base is either poured in the excavation or field adj u stments a re req u i red, to avoid uti l ities. precast offsite and lifted and placed into the excavation. However, qual ity issues need to be effectively managed In either case, the concrete is poured i nto formwork to if cast-in-place bases are specified for a project. These maintain the shape of the base. Concrete foundations issues may include, but are not l i m ited to: typical ly contai n anchor bolts to su pport the pole, • delivery from a supply source affects the delivery reinforcing steel for strength, and conduit(s) for wire entry temperature of the concrete, which in turn affects into the pole. All of these items are set into the forms prior quality. to pouring the concrete. Hig h-mast foundations req u ire special consideration and engineering design, typically The ava i l a b i l ity of concrete. The d istance of • The a mbient tem perature of the insta l lation day, as wel l as d u ring the c u ring period. completed by a geotechnical and structural eng ineer. The practica l ity for a m i n i m u m curing period These cast-in-place foundations are considerably larger in dia meter and depth, with six or more anchor bolts before p lacement of the pole and remobi l ization to support the high-mast pole; a typical fou ndation is of construction crews within the project timelines. shown in Figure 6-43. It sho u l d be noted that this also affects the overa l l time that contractors are present a t the site a n d positioned near traffic, which is a potential safety concern. • The avai la bi lity for inspection to ensure quality. I nsta l lation proce d u res that req u i re particular attention and q u a l ity control include proper reinforcing-cage placement, top of base elevation control, and proper alignment and placement of the a nchor bolts. Figure 6-42. Typical precast (left) and cast-in-place Concrete fou ndations may also be cast into retaining (right) foundations. (Photos courtesy of AE Concrete walls, bridge pa rapets, and other structu res, subject to Precast Prod ucts) the approval of the structural engineer designing the structu re. In these cases, the pole fou ndations sho u l d be desig ned as part o f t h e structures, taking into account the pole loadi n g . I t is critical that t h e size and spacing o f t h e a nchor bolts i n a foundation be verified prior to construction and coordinated with the pole manufactu rer. Poles w i l l often have a fixed base plate size and a fixed bolt-hole size and spaci ng, which m ust match up with the a nchor bolts cast into the foundations. 6.8.2 Steel Screw-In Type Foundations. Steel screw­ in-a nchor bases effectively address a l l the concerns listed for cast-in-place bases as wel l as backfi l l compaction Figure 6-43. Example of a high-mast foundation with issu es. H owever, the screw-in a nchor bases req u i re a anchor bolts and conduit. (Photos courtesy of WSP) su bstantial torq ue to install, necessitating avai lability of 6-34 Lighting System Components appropriate installation equ ipment. Bases a re typica lly of b u rial. Conseq uently, they w i l l not work in all soil installed in a bout 20 min utes. The man ufacturer of the conditions. Where direct-burial poles a re to be used, the screw-in foundations should provide specifications for designer should verify that the foundations are suitable designing with these fou ndations. These foundations for the soil conditions. are not recommended i n u rban areas with u nderground utilities i n close proximity or in a reas with rocky soils. Concrete poles can be very cost effective because a Screw-in bases a re typically fa bricated i n 1 68 mm, sho u l d not be considered where brea kaway type bases 220 m m and 273 m m diameters, in 1 .5 m and 3.0 m are req u i red to meet clear zone standards. separate foundation is not req u ired . Direct-burial poles lengths. The steel screw-in-anchor base p late should be of sufficient dimensions to match the specified pole height, and predrilled or slotted to match the pole's bolt 6.9 Poles and Related Hardware circle diameter (BCD) and bolt size. 6.9.1 Pole Materials. Poles range in style, height, shape, Screw-i n a nchors should be galvanized for corrosion material, and color. A common material for roadway resistance. Ga lvanic soil reactions and soil chemical light poles is steel. Steel poles a re typically galva nized composition may affect bu ried metal components a nd for corrosion resistance. They may be pai nted or sho u l d be explored before a metal screw-i n foundation powder-coated for im proved appearance and corrosion is specified. resistance. Other typica l materials include a l u mi n u m, sta i n l ess steel, concrete, wood, and fiberg lass. Concrete A screw-in type fou ndation is shown in Figure 6-44. poles may be supplied with exposed aggregate finishes for a different aesthetic appearance. A typical installed pole is shown i n Figure 6-45. Figure 6-44. Typical steel screw-in foundation. Figure 6-45. Typical steel pole on concrete foundation, (Photos courtesy of Helical Pier Systems Ltd.) showing foundation and pole hand-hole. 6.8.3 Direct-Burial Poles. Poles can be supplied for Gen era l g u idance for the use of the various pole d i rect burial in the g round. Direct-buria l poles a re materials includes: available for bollard, post-top, davit-style, mast-arm, and truss-style arrangements, as well as high-mast. • Steel poles. Steel poles are typical ly available from numerous suppliers in a wide ra nge of different styles and sha pes. Galvan ized poles typically Where a direct-burial pole is used, it should be i nsta l led offer superior corrosion resistance over pai nted and backfil led similar to a precast concrete base. Direct­ or powder-coated poles. Ga lva n izing can have a n burial poles a re typically su ppl ied with a standard depth inconsistent finish, which c a n darken over time. I n 6-35 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities • areas where aesthetics is a concern, paint or powder­ Energy-absorbing poles work differently than poles with coating over the galva nizing should be considered. brea kaway bases. Energy-a bsorbing poles are designed Steel poles can be mou nted on brea kaway devices. to flatten and wrap a round the vehicle u pon i m pact. These poles a re typically attached to a concrete The vehicle is slowed and prevented from affecting base via a nchor bolts. other objects, such as tree or walls. Aluminum poles. Al u m i n u m poles are typical ly compa ra b l e ga lva nized The European Com m ittee for Standardization (CEN)'s steel poles, but they offer a more nearly uniform Passive Safety of Support Structures for Road Equipment finish. The su rface of an a l u m i n u m pole will oxidize (EN 1 2767),17 the Federal Handbook from the Federa l more expensive than • over time, but this w i l l not affect its strength or Secretary of Transportation (Mexico),7 and the AASHTO d u rability. A l u m i n u m poles are available i n a wide Roadside Design Guide (U.S.)2 define performa nce-based range of sizes and shapes. Aluminum poles can be standards for breakaway and energy-absorbing poles. mou nted on breakaway devices. These poles are Accord ing to a report prod uced by the FHWA, "Energy­ typically attached to a concrete base or screw base absorbing poles flatten u pon i m pact, but do not break via anchor bolts. away. They are used mainly in Finland and may be usefu l Concrete poles. Concrete poles can be su pplied with exposed a g g regate fi nish for superior aesthetics over other pole types. They can be d i rect-buried or attached to a concrete base via anchor bolts. Concrete poles should not be used on breakaway devices. They are usua l ly much heavier than steel or a l u m i n u m poles and react differently upon i m pact. Concrete poles should usua l ly be used in a n u rban a rea where the clear zone is not a n issue. Concrete poles maintain their appearance and require m i n i m a l maintenance over time. • Fiberglass poles. Fiberglass poles are limited in styles and shapes and are typically more expensive than steel poles. Fiberglass poles can be supplied pre-finished in various colors, but the color may be susceptible to fading as a result of exposure to UV. They can be direct-buried or attached to a concrete base via anchor bolts. Some suppliers offer breakaway devices built into the pole itself. Some fiberglass pole suppl iers offer energy absorbing poles. • in the Un ited States, in areas where breakaway poles a re not desirable. New types of poles meeting the standard and suitable for wind speeds of up to 23 m per second have been installed." As of mid-2005, the only pole types with energy-absorbing properties are made from fiberg lass. This w i l l vary from supplier to supplier and should be investigated prior to specifying a ny product. Poles are typical ly attached to concrete fou ndations with a nchor bolts (see Section 6.8.1 ). In the case of the screw base, the attachment is made with connection bolts (see Section 6.8.2). To make the attachment, a pole will have an attached base plate with holes located to match the bolt pattern on the fou ndation. Poles may also be d i rect-bu ried (see Section 6.8.3), which eliminates the need for a separate fou ndation. This practice is q u ite common in the case of concrete poles. This is also common with steel poles where meta l corrosion is not an issue or can be economically mitigated . Galvanic soil reactions and soil chemica l Wood poles. Wood poles should be considered com position may affect direct-burial metal poles and for temporary lighting, or when l ig hting arms are should be investigated before such a pole is specified. installed on utility poles. Wood poles a re direct­ bu ried. The h o ll ow i nterior of a pole a lso may act as a raceway for w i ring to a l u minaire. Poles sho u l d have a hand-hole Poles may be equ ipped with a breakaway, frangible, at the base for access to wiring splices and fusing. The or slip type device between the foundation and pole hand-hole should face opposite to the d i rection of to a l l ow the pole to break away upon i mpact. This travel for that side of the roadway. safety device is further elaborated on i n Section 6.9.4. A pole with a breakaway base is often referred to as a Poles are typica lly engineered by the manufactu rer's breakaway pole, fractu re pole, or yielding pole. structural eng i neer to meet the l oca l codes and 6-36 Lighting System Components standards for the a rea in which the pole is being In general, round poles perform better than square installed. Often a road a uthority will have specific pole poles, and steel performs better than a l u m i n u m when standards and structural criteria. insta l led in the above a reas. Consideration should a lso be g iven to the addition of dampening devices. The The effective projected area (EPA) of a n object is the type of dampening device should be recom mended by prod uct of the object's projected area as "seen" by the pole supplier. the wind and the object's wind d rag coefficient. Poles a re sized per their EPA capacity. The a rea includes everything mou nted on the pole, including but not lim ited to l u minaires, a rms, brackets, cameras, and banners. The primary selection of the poles w i l l depend on several factors, such as width of the road, l u minaire weight, the location of the project, and the wind load of the region. Genera l l y, shorter poles a re used for na rrower roads, usua lly close to residential areas, tal ler poles for wider roads. It is critical that pole foundation and/or mounting design be considered ca refu lly and coordinated in the overa l l desig n of roadway, bridges, downtowns, and historical a reas. 6.9.2 Pole Placement (Spacing). The careful and strategic placement of l ig ht poles a l ong the roadway is a n i m portant concern for the lighting designer (refer to the appropriate application chapter in Part II - Design for add itional i nformation). Along with providing a l ighting system that suppl ies the req u i red l i g hting, the designer needs to confirm that support structures are properly designed and ca refu l ly located to m i n imize adverse effects on the traveling publ ic. Where possible, sig nal poles should be designed to accommodate a l u minaire extension arm mou nted to the pole. This will reduce c lutter, the n u m ber of roadside objects, and costs. Poles should meet the releva nt certification requirements and be desig ned by a loca l professional eng ineer (PE) or equ ivalent. Pol e placement issues facing a designer include: • Obstruction of view. Poles should be placed so that they do not obstruct the view of sig ns, and When deci d i n g on pole selection the designer or so that the brig htness of the l u mi naires does not eng ineer should consider not only the pole material seriously detract from the legibility of the signs. but a lso the pole shape, application, and area in which In addition, l ig ht poles should be careful ly spaced the pole is to be installed. Light poles can vi brate when located adjacent to overhead signs structu res in different modes and at d ifferent freq uencies. It is so that d istracti ng shadows are not cast from the very difficu lt or a lm ost i m possible to pred ict when signs onto the roadway surface below. poles will be affected by vibration, but all poles are • Height restrictions. Federal and l oca l a i rport authorities may have height restrictions for light susceptible. Ca refu l consideration should be g iven to pole i nsta l lations i n the fol l owing a reas to ensure proper poles placed adjacent to a i rports and i n their pole selection: fl ight paths. The presence of overhead power l i nes • • Areas that experience l ow, constant winds a nd/or may also restrict the height of light poles. Some are classified as special wind zones ju risdictions have bylaws restricting the height of poles for defined a reas. Areas adjacent to a i rports, wind farms, parking decks, and other a reas where winds may be g reater than in the general surrou nds • Any area in flat open terra i n or footh ills • Anytime the pole load (incl uding l u m i naires and • Medians. Locating structural su pports for l ig hting u nits within a median area may be appropriate if the width of the median is sufficient (if the pole is knocked down, it will remain within the median) or if shielded with a barrier. Locating poles i n brackets) may be low (EPA less than 0.2 m2 or 2 ft2); a medians can reduce t h e num ber o f lighting poles pole's loading can help stabilize it such that it reacts and conduit by 50 percent from that required for less in windy conditions than will an u n l oaded or shoulder lighting, thus red ucing cost. Maintena nce, very lig htly loaded pole however, can be affected, as fast-lane ( left-lane) 6-37 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities • • closures may be more problematic than closures of and concrete footing that are desig ned to shear or slide slow lanes (ri g ht la nes). apa rt when struck. Gore areas. Locating light poles with in the clear zone of both a main lane and a ramp at a gore In restricted, u rban environments, breakaway bases area is not desirable. It should be avoided u nless should be used un less engineering judg ment shows that the pole is l ocated behind or atop a longitudinal pedestrian safety could be compromised or the posted traffic barrier or behind a crash cushion or i m pact speed l i m it does not support the use of breakaway attenuator. devices. In addition to the brea kaway support, the pole Maintenance considerations. The maintenance and servicing of roadway and sign lighting u nits should be considered when designing the lighting system . The selection of the light pole location should a lso include consideration of the potential safety risks i mposed on maintenance personnel servicing and maintaining the lighting equ ipment. 6.9.3 Clear Zone Requirements. Although a n u nobstructed roadside i s h i g h l y desira b l e from a roadside safety viewpoint, some appurtenances such as l ig ht poles shall be p laced near the traveled way. As roadway lighting is a road safety enhancement, poles should be p laced in such a way that they do not present an increased risk to errant motor vehicles. Along roadways, roads and streets, poles should be placed outside the clear zone, as defined in the latest edition AASHTO Roadside Design Guide (U.S.)2 and the TAC Geometric Design Guide for Canadian Roads1 or have a su itable brea kaway device if l ocated within the clear should util ize electrica l d isconnects in the base to reduce the risk of fire and electrical shock after the structure is struck by an errant vehicle. Additional i nformation and definitions may be found in AASHTO's Roadway Lighting Design Guide, GL-7.18 I n addition, the AASHTO Roadside Design Guide covers general information on the crashworthiness of l u m i na i re su pports.2 6.9.5 Pole Attachment Hardware. h a ngers, flowe r basket ha ng ers and associated irrigation systems, power d istri bution cabinets, traffic sig ns, and receptacles for orna mental l ig hting. Typical pole attachments are shown i n Figure 6-45. When insta l l i ng attachment hardwa re, the additional wind load due to the proposed attachment can affect the pole and foundation loadi ng, particula rly in the case of ban ners. Poles and fou ndations should be designed to accommodate such additional loads when a ntici pated. Smaller devices should have only minor i m pact on the pole load and will not genera l ly be a n issue with respect zone. Determining the clear zone is a function of design speed, traffic vol umes, the presence of fil l and cut sl opes, the steepness of the slopes, and the horizontal cu rvature of the road. 6.9.4 Breakaway Bases. The design of the lighting system shou l d include brea kaway supports and a n appropriate electrical disconnect when t h e l ight poles cannot be placed outside of the roadside clear zone or behind a longitud i n a l traffic barrier or crash cushion. A brea kaway su pport is a design feature that a l l ows a l u m inaire support to yield, fractu re, or sepa rate near g round level u pon impact by an errant vehicle. Brea kaway bases may a lso be referred to as slip bases, frangible bases, or frangible cou p l i ngs. These devices Figure 6-45. Typical pole attachments. consist of bolts or para l lel plates between the pole base (Photo cou rtesy of West Coast Engi neering) 6-38 Attach ment hardware for light poles typica l l y incl udes banner Lighting System Components to pole l oad ing, but it is always prudent to consult with l ighting can also be reduced as the level of activity is the pole manufacturer's structural eng ineer to be sure. red uced, at specific times d u ring the hours of darkness. Drilling holes in the pole shaftto accommodate cabinets, sou rces now enable the user to turn specific individ ual attachment hardware, or wiring may negatively affect or g roups of lig hts on or off, or to adjust individ ual the strength of the pole. Prior to drilling holes in a pole or g roup l ight levels u p or down as needed. These shaft, the desig ner or contractor should contact the new control systems enable fu l l customization-from New dig ital technolog ies in both controls and l ig ht manufacturer's structural eng ineer for a pprova l . individual l ight points to complete lighting systems-in order to meet the specific needs of each user. Adaptive The manufactu rer's structural engi neer should a l so be control systems can make adjustments d u e to changing consu lted for approval prior to placing traffic signs on a mbient light levels, pedestrian activity, vehicular traffic a pole, to provide assura nce that the additional wind a n d even weather conditions. loading can be accommodated. This section presents a n overview of l ig hting control Attachments of a ny kind should be avoided on poles tec h no log ies, some of which are new and evolving, and with a breakaway base un less it can be proven the others which have a proven history (for examples, refer breakaway device has been designed to acco m modate to ANS/I/ES LP-6-20, Lighting Practice: Lighting Control the additional load from the attach ment. Systems - Properties, Selection, and Specification19). An informative g u ide to cu rrent goals and best practices can be found in Annex B of this Recom mended Practice. 6.1 0 Roadway Lighting Control Systems Electric outdoor l i g hts a re genera l ly controlled in g roups 6.1 0.1 Control Technologies via relays (contactors) and photocel ls, or control led individ u a l ly with photocells mou nted on the l u minaires. 6.1 0.1 .1 Standalone Technologies. This section covers In some cases, time switches (also called timeclocks) are control sol utions that do not require a network or other used to control the l ighting. Today's d igital technology, separate device to operate. in both control systems and l ight sources, offers new potentia l to better control the l ig hting system and H istorical ly, cad m i u m su lfide (CdS) lig ht-sensitive cells provide the right amount of l ig hting when req u i red. (act u a l ly light sensitive resistors) were used i n series These types of controls a l low the l ig hting system to with the pickup coil of a n AC relay. These were generally adapt the light levels to the a mbient conditions. Better called e lectro-mechanica l or magnetic photocontrols. l ig hting controls can result in improved visibil ity and N ewer, potential savings in both energy and maintenance costs. advantages, including the ability to use a more stable e l ectro nic photocontro l s offer severa l phototransistor (or photodiode) a n d m ore accu rate It is i mportant to note that these new systems, while turn-on and turn-off control. bringing the potential to i m prove visibility as well as considerably reduce both energy and maintenance Cad m i u m su lfide cel l s a re sti l l used on what is called a costs, a lso bring a sign ificant and long-term investment. thermal photocontrol. The thermal photocontrols do For that reason, the user and designer should u nderstand not have the advantages of a n electronic photocontrol, the fu nctional ities and consequences of the d ifferent but they are stil l used because of their low price and technol ogies, each with its own cost-benefit a n a lysis. beca use they a re more compact and are used i n the smaller "button" photocontrols. The d rive to reduce energy consu m ption and its related costs has led to new strategies for l ig hting controls. I n Fi ltered photodiodes (also known as phototransistors) many cases, particularly in parking lots, fu l l l i g ht output are mostly modern photocontrols, which use silicon is not req u i red throug hout the nig ht, particularly after phototransistors (or photodiodes) to detect light levels. busi ness hours. In some cases, street and roadway Due to their much higher response to the infrared (IR) 6-39 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities spectrum than the visi ble spectrum, the presence of of the light. If these levels are set high, it w i l l cause the infrared wavelengths can shift the control points of burn time to be excessive, causing i ncreased energy sil icon-based photo controls that are ca l i brated with usag e. If these levels are too low, the light might not visible light sources. Hence, many l ighting authorities turn on due to light from other electric sou rces (such are req u iring I R-filtered or I R-blocking photocontrols to a l low operation based on visible l ig ht levels. as other l u m inaires). They can be specified in various types and with various on and off settings and voltages, Cad m i u m su lfide cells were used for detection of visible l ight levels because their response matches very well with that of the human eye and is very insensitive to and they typically mount onto the l u m i na i re. Figures 6-46, 6-47, and 6-48 show exampl es of lighting system control components. IR. However, their sensitivity changes with age, a nd their requirement for light conditioning has led most manufacturers to move away from them and embrace silicon detectors. In an effort to cope with the IR sensitivity of silicon, many manufacturers have turned to various methods of filtering in an effort to cancel the effect of Com ponents A . Daylight Sensor B. Control Module C. Wireless Antenna (not shown in plan) D. llluminance Meter (not shown in elevation) IR on the control levels. In general, this filtering might be accomplished optical ly or electronically. An optical filter might simply be a piece of plastic fil m placed in front of the silicon phototransistor, or it might be molded as part of the phototransistor's lens. The most common method of electronic IR filtering is to use an I R phototransistor that i s sensitive t o only I R a n d subtract Figure 6-46. Managed lighting system components. it from a phototransistor that is sensitive to both IR and (Graphics courtesy of Streetlight I ntel l igence) visible light, leaving only the visible light response. 6.1 0.1 .1 .1 Dusk-to-Dawn D u s k-to-dawn Photocontrols (Photocel ls). photoco ntrols, as i m p l ied, t u rn a l u m inaire on at d usk and off at dawn. They are g enera lly packaged i n a l ocking-type (N EMA, twist l ock) 3-terminal device measuring a bout 7.6 cm (3 i n.) in dia meter, and a re compliant with ANSI C 1 36.1 0. The light levels at which these photocontrol s turn lights on Figure 6-47. Photocell. and turn off a re i mportant in determining the burn time (I mage courtesy o f WSP) Figure 6-48. Typical photocell on a Luminaire 6-40 Lighting System Components 6.1 0.1 .1 .2 Part-Night Photocontrols (Photocells). These Definition Standard, a Joint Standard of the American are similar to the dawn-to-dusk photocontrols described Association of State Hig hway Tra nsportation Officials a bove, but i nstead of using a time switch (sometimes (AASHTO), the I nstitute of Tra nsportation Engineers (ITE) called a time clock) in series with a photocontrol, they and the National Electrical Man ufacturers Association can turn the l i g hts on at d usk and shut the lights off at a (NEMA). specified time (or percent of nig ht), thus saving energy. They measu re the length of each night and thereby 6.1 0.1 .1 .4 Astronom ical Time Switches. An astronomical adjust themselves each n i g ht as the seasons change. time switch, also known as a n astronomical timeclock, In this type of appl ication, one or more l u m i naires with works much the way a typical time switch works, but in standard dusk-to-dawn photocontrols may be used it also knows the theoretical sunrise and su nset times for as "night lig hts" to su pply m i n i ma l lighting, while the each particu lar day of the year at a particular coordinate others save energy d uring the late night, after business (location). This is usefu l should one wish to turn on a hours. light at su nset (and/or off at sun rise) without the use of A s l i g htly different va riation of a part-night photo fol l ows su nset (and precedes sun rise), an offset time, control receives a very precise time signal via radio from say, 10 min utes, can be used so that the light fixture is government maintained time sta ndards. These g ive the not tu rned on or off too early (or too late, for sun rise). a photocontrol (photocell). Because twilig ht genera l ly added benefit of automatic time resynchronization after a power outage, without the need of being connected Astro n o m i c a l to a network. disadvantage in that they do not compensate for cloudy time switches have a potential days or other varia bles that ca n affect l i g ht levels 6.1 0.1 .1 .3 Time Switches. Time switches traditiona lly have been used to turn a light on and off at specific around su nrise and sunset. Effects from m o u ntains may also sh ift the effective su nrise and su nset. times; the device will need to be cal i brated for the local time. Assu m i n g the time switch is not connected to Most astronomica l time switches do a llow for time shifts an outside i nformation source (such as the i nternet), due to dayl ight saving time. the a b i l ity of the switch to m a i nta i n an accu rate time could be a concern, particularly in the case of The function of an astronomical time switch may a lso electromechanical timers. Many time switches also do be incl uded within the control functions of a networked not allow for time sh ifts due to dayli g ht saving time. system (see Section 6.1 0.1 .2). A time switch can be put in series with a photocontrol 6.1 0.1 .1 .5 Motion Detectors. Motion detectors can be (photocell) in such a way that the l i g ht l oad w i l l come used to change the state of a light (or m ultiple of lig hts) on at dusk and turn off at a chosen time. There are when motion is detected. This change of state m i g ht be a lso part-night photocontrols ava ilable that integ rate to t u rn on a l i g ht or to change the light from a d i m med a photocontrol with an internal switch (see Section state to a fu lly on state. These are commonly used 6.10.1 .1 .2 Part-Night Photocontrols). for indoor a pplications (where they a re often called occupancy sensors), where elements like b lowing leaves The function of a time switch is also generally included and running animals a re not usually a problem. Fa lse within the control fu nctions of a networked system, detection caused by such issues as a n i ma l s, blowing discussed in Section 6.10.1 .2. leaves, and wind-vi brating poles can make it more For standalone appl ications that d o receive time environments. Motion detectors can a lso be adversely updates from a master time reference, the parameters affected by changes in a m bient tem perature. Im proved cha l lenging to i m plement motion detection in outdoor of Global Time, Global Daylight Savings Time, Standard PIR (passive infrared) detectors, radar, hybrid systems, Time Zone, Local Time, and Daylight Saving Time are and i ntel l igent cameras that are better at preventing formatted accord ing to the NTCIP 1 201 V03 Global Object fa lse detection may be consid ered, and d o help in 6-41 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities d e a l i n g with the outdoor envi ronment. If the user determines that motion sensing functional ity is needed, the designer or engineer can specify the a ppropriate detection pattern for that a pplication. It is im portant to remember that outdoor application scenarios may present sign ificant obstacles to successful design a n d operation, i n c l u d i n g m issed a n d false Management Station detections. The d esigner should act judiciously when attempting to employ outdoor motion sensors in new or retrofit designs. Figure 6-49: Management station, data logger, and streetlight controllers. (Graphic courtesy of Jim Frazer) Motion detectors can a lso be used in conj u n ction with a networked system (see Section 6.1 0.1 .2) to provide on-demand l ighting, which can result in energy savings. provide a practical way of doing so. Networked lighting systems now provide the ability to monitor, control and 6.10.1 .2 Networking and Communications Technologies. even create systems that have the ability to react to This section covers several technology elements that changing environments: adaptive lighting. A thoughtful, are essential parts of an integrated and interdependent well-informed approach to re-engineering street lighting system of advanced street lighting controls. These include systems is emerging to create cost-effective opportunities the management station, the data logger, and street to reduce power consumption and maintenance costs. lighting control lers, as well as other terminal devices. These are represented in Figure 6-49. 6.1 0.1 .2.1 Management Station. A management station (sometimes referred to as a central management system, Whereas in the past it has not been practical to dim, CMS) is defined as one or more host computing platforms instantly turn on, or instantly restart HID light sources, LEDs that control the field devices (see Figure 6-50). They may STAR CONFIGURATION MESH CONFIGURATION ··»- FIELD DEVICES ·· ·.·_·-·�- :�::·�-��: ········':'".. ·... .. . . . .$0--·" ·· ... ·· ... (f; GATEWAY . .· NETWORK INFRASTRUCTURE WIRED l•thern.I) METER . . = = = = SERVER DATABASE CENTRAL MANAGEMENT SYSTEM REMOTE WORK STATION REMOTE WORK STATION Figure 6-50. An alternative view of networked control systems. (Graphic courtesy of US Department of Energy) 6-42 Lighting System Components be hosted by a third party provider or by the maintaining Management center com m u nications interface with agency. Mobile management stations are devices that can either a data logger or the actual field device (streetlight be used at a fixture or electrical service cabinet. controller) and can be g rouped into two classifications. These are known as proprietary or standardized protocols. For networked controls, the management station is Proprietary protocols provide a single point of contact located where the com m u nications with the l u m inaires for initial system acquisition as well as maintenance. a re collected and analyzed. Street lighting operators Alternatively, standardized protocols a l l ow m u ltiple sho u l d consider a req u irement that a l l manufacturers vendors' products to operate together. Support of of l ighting com m u n ications prod u cts tra nsmit their these standard ized devices and systems can range from data to their management center in a lang uage that the interoperability for some (or a l l) features to complete management station can use. Designers should req uire intercha ngeability of different vendors' products. that the com munications i nterface between a l l devices sho u l d be detailed by an interface control docu ment The reader is referred to Chapter 7 for more information (ICD). The ICD defines the "language" that the systems on standards development. and subsystems should use. 6.1 0.1 .2.2 Data Logger. A data logger is a physical These systems can be built using a variety of architectures, component that collects and stores i nformation on from hardware and software hosting at the management the state and operation of electrical and l i g hting center, to hosting at an offsite location. When deciding management system between a networked lighting control system with fun ctional ity that may be included in va rious system devices. Data l o g g i ng is a standardized communicationsand a system with proprietary com ponents, not l i mited to the data logger. For a large­ communications, street lighting operators should carefully sca l e system, such as for a large city, some temporary investigate aspects including interoperability between data l ogging may take place at the l u m i naire controller system components, ease of deployment, and tooling for so as to not req u i re tra nsmission of data on a constant basis. S i m i l a rly, the data-logger field device may commissioning and asset management. store temporary data before passing the data to the Figure 6-51 describes a roadway l ighting management management station. system that incl udes control and mon itoring of electrical Exa mples of data than can be logged include: services and branch circu its. • Luminaire switch state • Luminaire lamp condition Lumlnalre 1 Luminaire burn condition Lumlnaire N Data Logger Luminaire burn time Electrical Service Period ic l u m i naire burn time Branch Luminaire temperature Circuit 1 Management Station Luminaire pole condition Branch Circuit N Relay switch state Power meter switch state At Management Center Location . . . . ' . . . Period ic power meter measurement Management Station Power meter cond ition At Fleld Location . . . . . . . . . . . . Ground fau lt switch state · · · · · · · · · · · Roadway Lighting Management System Figure 6-51. Schematic diagram of a roadway lighting management system. (Gra phic courtesy of Jim Frazer) • Period ic g round fault measurement Additional logging functions can i nclude: • Off- l i ne log data 6-43 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Configu ration of logging service a n d may be l i n ked to the i nternet, the designer should • Capabilities of event logging services ensu re that the proper cybersecurity mechanism is • Nu mber of events cu rrently logged • Attention should be paid to the protocols that may be used between these various components, si nce interoperability or i nterchangeability between various manufacturers may be a n issue. 6.1 0.1 .2.3 Streetlight Controllers. Streetlig ht control lers (sometimes referred to as nodes if using a mesh topology) are terminal devices that com m u nicate with the data logger over ded icated wires, via power- l i ne carrier, or via wireless e q u i pment. Each street l i g ht control ler may have control, measu rement, loggi ng, and comm u n ication features. Dedicated wires a re a simple, reliable means of com m u n i cati ng with l u m i na i res. Power-line carrier costs ca n rise when n u merous transformers are present because additional hardware is requ i red. These "bridges" are necessary to route the signal around transformers. Wireless transm itters and receivers could have l i mitations, such as range and obstructions, depending on the specific topology and technology. Wireless systems can use different frequency bands, such as the l icense-free ISM bands.. (e.g., the 915-MHz and 2.45-GHz center bands) or privately licensed frequencies. Furthermore, a type of topology such as mesh or star (point to m u ltipoint), or a combination, will be used. It is good to understand the advantages and disadvantage of each of these in order to choose the best solution for a particular application. 6.1 0.1 .2.4 Data Logg ing. Depending on the needs of the user, both operational parameters and exceptional conditions may be recorded or logged. This function can occur physica l ly with in the streetlight controller or within the data logger (see Section 6.10.1 .2.2). 6.1 0.1 .2.5 Data Security. Since roadway lighting systems rely on digital network com m u nication tec h nology •• ISM: industrial, scientific, and medical radio bands, internationally i mplemented by the vend er. 6.1 0.2 Adaptive Lighting Design. considerations noted The design here are m a i n l y related to energy savi ngs. However, the q u a l ity of the lighting a n d i m proved visi bil ity should a lso be consid ered . The items listed should be considered as part of the planning and design phases of a n outdoor l i g hting project. As a cautionary note, applying this i nformation req u i res a very sound knowledge and u nderstanding of roadway l i g hting and road safety. Local conditions (i .e., user needs from a l l stakeholder com m u n ities, including law enforcement) shall be s u pported. Therefore, it is recom mended that fu rther research and review be u ndertaken prior to adopting these design considerations, with respect to roadway l i g hting and road safety, with a focus on the specific application. New energy efficient l ight technologies and controls are now changing the landscape by offering potential energy savi ngs and performance benefits. H owever, with these advances there is an i ncreased level of complexity, which req u ires i ncreased expertise and u n d erstanding from owners and l i g hting desig ners. One major barrier to obtaining energy cost savings from an ada ptive control system can be the flat rate power ag reement from the utility provider, which is typical ly based on a fixed l u m i na i re wattage and usage over a m onthly or yearly period . It is recommended that a custom rate schedule or metering system be agreed to with the local electrical utility prior to proceeding with energy saving adaptive l i g hting controls if cost red uction is a priority. In terms of energy savings, adaptive l ighting involves va rying lighting levels to suit activity levels d u ring off­ pea k periods. Adaptive l i g hting is achieved via the use of l ig hting controls that a llow l u minaires to be di m med or tu rned off at predefined times. Simply put, by reducing light levels during non-peak periods, significant energy can be saved. Occupancy based control can a lso be reserved or the use of radio freq uency (RF) energy intended considered in a ppl ications where activity levels a re scientific, medical and ind ustrial requirements rather than for va ried. com m u n ications. (Source: Technopedia, https://www.techopedia. com/d efi nit i o n/2 7785/i n du stria 1-sc i entifi c-a nd-m ed i ca 1-ra di o­ ba nd-ism-ba nd. ) 6-44 Adaptive lighting controls will typica lly have the highest benefit for continuous l i g hting systems i n u rban areas. They c a n b e appl ied in r u r a l areas, though Lighting System Components they will have less energy saving benefits than in urban • Dimming to increase system life. In the case areas, where l ight levels are higher and more l ig hting of LED l u m i na i res, the lig hting designer m i g ht exists. consider the cost of i nsta l l i n g l u m i na i res with higher lumen o utput and a d i m m i ng system, to 6.1 0.2.1 General Considerations. main a l l ow for d i m m i ng the higher-than needed output techniq ues have t h e potential t o save power and reduce down to that req u i red to meet the i l l u mina nce light pol l ution with ada ptive l i g hting controls: criteria. The dimmed streetl ig ht will run cooler, • Three Reducing initial light output to maintained which can extend its l ife by up to 50%, compared levels. Light output from l ig ht sou rces depreciates to a streetlight that is set to its maxi m u m lumen over time. To maintain the m i n i m u m l ig ht levels output. on the roads and sidewalks, l i g hting designs are • • Match light output to pedestrian activity levels. based on maintai ned lamp l ife and therefore have a The a mount of l ight req u i red for a street or sidewalk maintena nce factor applied to the design to take into is based on two significant criteria: the classification account this depreciation. Designers may provide of the street itself and the level of pedestrian an initial level of lighting higher than the m i n i m u m activity. The classification of the street is based on maintained level. I n effect, roads a n d sidewal ks are the n u m ber of lanes and the volume of traffic and over-lig hted up u ntil the end of assumed lamp l ife. is defined by city admin istrators, who operate the One of the components of the l ig ht loss factor (LLF; street. The pedestrian activity level is esta bl ished see Section 3.1 .6) is lamp lumen depreciation (LLD). by the lighting desig ner by estimating the nu mber This factor is typically 70% to 90%, depending on of pedestrians on the sidewal k i n a single block the l ight sou rce. Applying a n adaptive technology (or 200-meter segment) for a g iven one-hour can control the light output over time so that the nighttime sample period. The sample period is l u minaires will operate at a maintained i l l u m inance typica lly the hour of hig hest nighttime pedestrian level for the entire maintenance cycle, thus red ucing conflict. If 1 00 or more pedestrians are a ntici pated, power i nput in the beginning and saving energy. the pedestrian activity level is high; if 1 1 to 99 Achieving equal light output over the fu l l life of pedestrians are anticipated, the pedestrian activity the fixture is a l so known as constant lumen output. level is med i u m; and if 10 or fewer pedestrians are Recent technological enhancements that also boost anticipated, the pedestrian activity level is l ow. performance include the a b i l ity to reduce light Pedestrian activity levels do not remain constant output by d i m m i n g l u minaires, and to set i nd ividual thro u g hout the hours of darkness, and i n most dim levels remotely. instances the n u m bers of pedestrians present in a Dimming areas that may be over-lighted. This given a rea will be d ra matical ly reduced in the late may be the result of a lack of lamps ava i lable in night and early morning hours. the appropriate wattage, or because a n owner has sta ndardized on a particular pole- l u m i naire­ Lighting designers typical ly have m i n i ma l data with wattag e combination for mai ntenance pu rposes. respect to variations in pedestrian activity levels Many roads a re in fact lig hted to wel l a bove for lig hted streets through the hours of darkness, recommended levels. A common scenario is a local and simply define the hig hest level a ntici pated. road within a subdivision where the lighting is If pedestrian counts a re not ava ilable, designers only required to be maintai ned to a m i n i m u m should work together with cities to establish average horizonta l i l l u m inance o f 4 l ux, but due to pedestrian conflict level through a nother means. poles, luminaires, and wattages, the design level In downtown core a reas or stadi u m d istricts with necessary to achieve the req u i red u niformity is 9 complex patterns of pedestrian activity tied to l ux. In this case, an adaptive system cou ld be used hol iday and event sched u les, the opportunities to reduce levels to those required. D i m m i ng or for d i m ming may be more or less significant than reduction of l i g hting does not change u niform ity i n a reas with predictable vol u mes of pedestrians if appl ied equally to all l uminaires in an i nstal lation. at reg u l a r hours. The pedestrian activity levels in 6-45 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities residential and industrial areas a re very predictable. for residential streets can vary based on pedestrian volume I n commercia l areas, activity levels should be tied (activity). For example, it is recommended that a local into the general operations of businesses. When street with high pedestrian volume be i lluminated at a determ ining pedestrian activity l evels throughout higher level than a low-pedestrian volume local street (see the evening and morning hou rs, sound logic should Chapter 11, Section 1 1 .7). Pedestrian volumes on local be developed and applied. Levels need not be streets are certainly time dependent. Peak pedestrian a bsol ute and address every potential anoma ly. volumes will occur earlier in the evening and at night, It is the responsibil ity of the lighting designer to whereas early morning volumes will be quite low or zero. apply sound rationale and logic in determ ining However, there can be a peak in early morning pedestrian­ pedestrian activity and sched u l es for the l evels. veh icle conflicts. This should be reviewed, as it may be specific to a given area. Where there is a change in the Reducing l ig ht levels based on pedestrian activity volume of pedestrians, the local street lighting levels can l evels is not recom mended in a l l lighting scenarios. also be reduced in consideration of this. For example, a local Scenarios where reducing l ight levels i n off-peak street with high pedestrian volume can be dimmed to the periods is not recom mended include: light level of a local street with low pedestrian volume. 0 Signalized intersections. Signalized intersections typica l ly i nclude pedestrian crossings. Pedestrian Vertica l i l l u m i nation is a key consideration for the conflicts with vehicles a re very likely at signalized detection of pedestrians and cyclists. Figure 6-52 i ntersections, so the l i g hting should not be shows the vertical and horizontal i ll u m i na nce produced by a motor vehicle's low-beam headlig hts,"* with the reduced from design levels at intersections. 0 Midblock crosswalks. The decision not to d i m m idblock crosswal ks fol l ows t h e s a m e logic a s stated for signalized intersections. 0 Roundabouts. Due to the complex geometry in rounda bouts and the ineffectiveness of fixed head l ights within the tight roundabout circle, d i mming should not be applied at these facilities. Roundabouts a re a n alternative to sig n a l ized i ntersections; thus, l i g ht i n g should not be reduced from design levels at roundabouts. 0 red a rea showing any val u e at or above 1 lux (0.09 fc). The 1 .5-m (5-ft) high vertical objects were placed to the right in the model, along the sidewal k area, providing a su rface for determ ining the vertical l ig ht i l l u m ination on pedestrians. The first vertical rectangle is at 30 m (98 ft) from the motor vehicle headlamps, a n d each subsequent vertical rectangle is spaced at 1 5 m (49 ft). The vertical i ll u m i nance (at varying heig hts on the face of the object) of 1 lux from the vehicle's hea d lamps is significant in this model. Therefore, the recommended vertical i l l u m ina nce level of 1 lux (for Railway crossings. Ra i lway crossing l i g hting is a si dewa l k with low pedestrian activity [see Section provided for detection of the tra ins and not 1 1 .6.3]) is achieved via motor vehicle head lamps for related to pedestrian activity l evels. Therefore, an extended distance in front of the veh icle. Horizonta l reducing l i g hting levels d u ring off-peak periods i l l u m inance extends from 30 to 40 m (98 to 1 31 ft) from is not recom mended. the vehicle headlamps and therefore wou l d not meet the recommended horizonta l l ig ht levels, especia l ly 6.10.2.2 Specific Design Considerations. Each specific considering that horizontal i l l u m i na nce criteria a re roadway l i g hting appl ication l isted in this section genera l higher than the associated vertical criteria. includes suggestions and recom m endations for l ight l evel reductions and energy savings. This modeling clea rly shows sig nificant i l l u m i nation contribution from motor vehicle head lamps. Though 6.1 0.2.2.1 Residential Streets. Lighting on residential motor vehicle head lamps provide a level of visi bility i n roads typically makes up a large percentage of a city or municipality's lighting infrastructure. Lighting on residential Head lamp data were provided in 2007 b y t h e Virginia Tech roads serves the driver and provides a sense of security and Tra nsportation Institute (VTTI), a n d the modeling of the headlamps was undertaken in 2007 by Parsons Brinckerhoff (now guidance to pedestrians. The light level recommendations WSP) for review by the IES Roadway Lighting Committee. 6-46 Lighting System Components Figure 6-52. Graphic illustration of low beam headlights. (Graphic cou rtesy of Don Mclean) low-speed appl ications, fixed roadway l ig hting is still of Simply turning lights off d u ring off-peak periods has val u e in providing visibility and a level of secu rity and been undertaken by some com munities. However, this comfort to the local residents and pedestrians. practice is not recom mended without extensive review, research, and public consu ltation. To provid e some level of lighting, a reduction in roadway lighting l evels in an off-peak period (i.e., m id night to 5:00 With the advent of new roadway l i g hting sou rces a.m.) could be considered based on the contri bution of such as LEDs, with their advanced optical control, the motor vehicle head lamps. The level of reduction could un iformity ratio (often the l i miting design factor in the be i n the 30% to 60% range. H owever, it should be past for high pressu re sodi u m lighting on local roads) reviewed and assessed by study and eval uation. It is up is now more easily achieved, which a llows roads to be to the ju risdiction who owns the l ig hting to accept the i l l u m i nated closer to the recom m e nded maintained times and l ight level reductions for the off-peak period. average l ig ht levels. To reduce power consumption, Severa l cities, including San Jose, California, have begun strongly considered for local roads. ada ptive l ighting controls and LED l i g hting should be to adopt adaptive l ighting guidelines based on local conditions. Desig ners should refer to l ocal adaptive 6.1 0.2.2.2 Collector and Arterial (Major) Streets. Lighting lighting guidelines where ava ilable. Although a 20% on a rterial and collector roads should meet the to 30% difference in l ig ht level is not easily discernible, recommendations in Chapter 1 1, Section 1 1 .7. There a sudden change in light level will be noticed. It is is no basis for red ucing l ig ht levels below the lowest recomm ended that a ny changes in light l evel take place lighting criteria (i.e., low pedestrian activity level) for g radually to accommodate eye adaptation. the classification of the road (i.e., major or col lector). To 6-47 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities reduce power consu mption, adaptive l ighting controls activated lighting has the potentia l to save energy while and LED lighting should be strong considerations for improving safety. these l ighting applications. 6.1 0.2.2.5 Tu nnels. Lig hting in tunnels should meet the Adaptive controls can a l low for significant energy saving recom mendations in Chapter 14 - Tunnel Lighting. in a reas of high and medium pedestrian activity, as the level of activity is typically low i n off-peak periods. A tunnel wi l l have m u ltiple light levels, based on time 6.1 0.2.2.3 Freeways and H ig hways. Lighting on freeways tra nsition, and highways should m eet the levels recommended effectiveness. These can be ach ieved with l i g hting in Chapter 10 Highway and Interchange Lighting. controls that measure the l u m i na nce level outside hig hways a re typica lly h i g h -speed the tunnel and adjust l i g hting at the tunnel entrance of day (day or night) and the tunnel zone (threshold, Freeways and - facil ities where pedestrians a re not normally present. i nterior), for maxi m u m effi ciency and (threshold). For this reason, adaptive lighting should not be appl ied to reduce i l l u m ination below the recommended levels 6.1 0.2.3 I nventory Assessment. For new insta llations, without u ndertaking further research and assessment. a n i nventory assessment is not req u i red since the One factor that could a llow for reduced levels is reduced adaptive lighting system should be developed as part speed. Thou g h not yet fu l ly resea rched, fu l l level lighting of the l i g hting design. may be of less benefit where freeway traffic is g ridlocked at low speed d u ring rush hour periods. Speed sensors For conversions of existing i nsta l lations i n order to could be used to sense low speeds and adjust and d i m optimize savings and ensure that proper light l evels l i g h t levels d uring these low-speed periods. are achieved, an inventory assessment of the existing l ighting is reco mmended. Many roadways a re over­ As d river g u ida nce and vehicle col l ision red u ction l i ghted, creating an opportunity for energy savings a re the primary objectives, freeways and hig hways by s i m p ly red ucing i l l u mination to the recom mended provide a great opportunity to consider alternatives to levels. Roadway classification and pedestrian activity, l i g hting, such as retro-reflective pavement markings road geometrics (widths, nu mber of lanes, sidewal k and delineators (see Chapter 1, Section 1 .6). Further info), pole locations (spacing), mounting heig hts, and g u idance can be obtained through the publications wattages should be obtained from the city's geographic Guidelines for the Implementation of Reduced Lighting on information system (GIS) database. If no database exists, Roadways (FHWA-HRT-1 4-050)20 and Design Criteria for a su rvey of existing l i g hting should be u nderta ken using Adaptive Roadway Lighting, FHWA H RT-1 4-051 .21 aerial maps and existing electrical design d rawings. 6.1 0.2.2.4 Sidewal ks, Wal kways and Alleyways. Sidewalk The makes and m odels of l u m i na i res s h o u l d be l ighting should meet i l l u mina nce levels recommended esta b lished via consu ltation with the m a i ntenance i n Chapter 11, Section 1 1 .6.3, or those required by personnel. From this information, the photometric files the Authority Having J u risd iction (AHJ). To reduce should be obtained from the lighting suppliers, and energy consumption, adaptive l ighting controls and l ighting calcu lations for the roadways and wa l kways LED l i g hting should be strong considerations for these should l ighting appl ications. be underta ken using computer roadway l ig hting calcu lation software sho u l d be underta ken (see Chapter 8). Once the calcu lations a re completed, they Motion sensor-activated l ig hting is being considered should be com piled into a spreadsheet along with a l l in these a reas, instead of l ighting that rem a i ns on relevant data, for comparison with t h e recom mended continuously at night. The pol ice often prefer motion design criteria. sensitive lights in a l leyways so that activity can be noticed by neighbors or from adjoi ning streets, as the The length of roadway calcu lations shal l be u ndertaken l ights' turning on w i l l indicate activity. Motion sensor- for non-uniform spacing, for the g reatest spacing 6-48 Lighting System Components extant, and for most non-typical design scenarios. These The supplier sha l l provide the system management analyses should be performed for the entire length of personnel with operations and mai ntenance manuals the road. Typical roadway sections should be considered after the i nsta l lation is fu lly tested and in operation. in the analysis. This process will capture typical light These documents sha l l be provided to the operations levels that generally represent the i l l u mination provided department of the system manager. by the roadway's existing lighting i nsta l lation. 6.1 0.3 Adaptive Lighting Operations. To verify the c a l c u lations, sample l i g ht Adaptive level l ighting systems can sign ificantly i nfluence the operation measurements cou ld be u ndertaken on roadways and of l ig hting system; some the areas of i nfl uence a re sidewa l ks. Designers should ad here to IES guidance described in the su bsections that fol l ow. regard i n g light measurements as found in Annex A - Street, Highway, Tunnel, and Parking Area Field 6.1 0.3.1 Preventive Maintenance Analysis. It is good Measurements. practice for an agency to create cha rts and maps of malfu nctions a n d fai l u re rates by location a n d As part of the inventory, the system manager will need e q u i p m ent type from to detai l a l l new and existing l u m i naires. Depending records. A control system that includes a computerized work-ma nagement system on the project scope, the agency may also decide to mai ntenance management system (CMMS) also can inspect a n d d ocu ment the condition of the poles, create com ponent-failure rate reports and the mean foundations, and wiring. This will a l low the adaptive time between fai l u res (MTBF) index by component type l ighting supplier to plan a pilot installation with testing, or m odel and by age category. With some adaptive in order to properly a l l ow them to retrofit the l u m inaires systems the mean time to repair (MTTR) for different with their equ ipment. If the city has n u merous types of types and models of components can created by the l u minaires, this aspect may prove to be a substantial CMMS as wel l . challenge. It is i mportant to note that some streetlight controls include G PS functionality within the streetlight 6.1 0.3.2 I nventory Analysis. Analysis o f partial usage contro l ler, along with asset ma nagement tools at the can be key to m a i ntena nce contro l . By identifyi ng management station. These features greatly reduce the statistica l ly the hig hest-use parts and their relative resou rces req u i red for a post-instal lation a u d it. costs, agencies can invest their i m p rovement efforts on these areas of hig hest return. Pareto ana lysis and root 6.1 0.2.4 Deployment. The insta l ler should insta l l a l l cause a n a lysis can be appl ied to reduce the i ncidence equipment t o t h e supplier's specifications. T h e level of these fa ilures. of effort req u i red for the i nsta l lation of an adaptive l ighting system will vary with the man ufacturer and Pareto analysis is a formal technique useful where many whether a fixed or adjustable system is deployed. possible courses of action a re competi ng for attention. The supplier shall provide one or more technicians to delivered by each action, then selects some of the execute the start-up of the adaptive l i g hting system and most effective actions, those that deliver a total benefit test the system for proper operation. reasonably close to the maximal possible. In essence, the problem solver estimates the benefit The equ ipment supplier should provide training for Root cause analysis is a method of problem solving the system ma nagement personnel to provide a n that attempts to identify the root causes of fa u lts or u nderstanding o f t h e system and its operation as wel l problems. A root cause is one that, when removed as the mai ntenance req u i rements o f every component. from the problem fau lt sequence, prevents the final If the system has adjustable d i m m i ng capabilities, the u n desirable event from recu rring. supplier is to ensure that the system ma nagement personnel a re aware of the ways to ful ly util ize the These analyses can res u lt not only i n considerable featu res of the system . savings in material costs and inventory, but also i n 6 49 - ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities the labor and associated eq uipment costs previously 6.1 0.3.6 Other Considerations. expended on these fa i l u res. Analysis can also be a pplied need to be determined and implemented based on i n reviewing part specifications and past fai l u re and the u n i q u e needs of the agency operating the system . mai ntenance req u i re ments h istory, responsiveness Cu rrent operational pol icies c a n b e enha nced in terms Operational pol icies of vend ors and man ufacturers in meeti ng s u p p ly of both speed a nd breadth by the creation of policies requirements, and the total i n-house processing time that previous technologies simply did not a l l ow. New from the techn icia n's request for a part to its issue. operationa l policies and a few policy enha ncements that occur as a d i rect result of technology implementation 6.10.3.3 Work Management Ana lysis. Ana lysis are described below. is typica lly conducted thro u g h the CMMS to ensure that a l l labor, parts, and eq u ip ment recorded for 6.1 0.3.6.1 Asset Tracking. the agency have been accounted for properly on a often support real-time asset management through regularly sched uled basis. Work order activity analysis barcode scanning. By scanning parts and tools as they Dig ital radio vendors can is conducted to determine the accuracy of technician travel through the organization, users can maintain a reporting and job completion. Agencies monitor their documented "chain of custody" of assets; losses can be estimates against the actual time taken to complete the greatly reduced while confirming that the correct numbers work and revise future estimates if necessary. of parts are in stock, both at the parts depot and on each service truck. In addition, at each scan the GPS location The mean time to repair (MTTR) index can often be data are recorded, so managers know exactly where and created by the CMMS, including for different types of when each component was physical ly deployed. repair (e.g., by type or l evel of expertise req u i red), to identify where staff resou rces need to be supplemented. 6.1 0.3.6.2 Electrica l Safety Equipment. Ground fault detectors and interrupters can, a l most i n rea l time, 6.1 0.3.4 Asset Management. The actual l evel of service report dangerous system anomalies. Some adaptive can be determined by the col lected data and su bsequent systems offer g ro u nd fault detection. analysis. This wil l a l l ow better-i nformed decisions as to which programs to fu nd and at what l evel. This effort is 6.1 0.3.7 Energy Metering and Monitoring. As d iscussed a ided by the ava i la bility of asset management systems previously, the utility provid ing power should agree that track operationa l para meters in near rea l-ti me. I n with energy savings operations in order for the owner to addition, these systems c a n generate management benefit from the savings. It is therefore imperative this reports that q uickly document d iscrepancies between be negotiated prior to deployment. service goals and actual levels of service. 6.1 0.3.7.1 Ta riffs. Utility ta riffs are the publ ished The p l a n n i ng process should ensure that there is coll ection of rules, rate sched u l es, and terms and fu nding for conti nuing operations and mai ntenance cond itions for use of service. This a l l ows for the ana lysis of the system . It is a lso i m portant to consider the of cost savings to be had from switching from one light shorter replacement cycle of some components such as source to another, red ucing burn hou rs, achievi ng equal computers and other telecommun ications equ ipment. light output, and adopting adaptive l ig hting. 6.10.3.5 Electrical System Maintenance. Ju risdictions 6.1 0.3.7.2 Flat Rate Billing. The g reat majority of street may choose to outsource mai ntenance of their street a n d hig hway l ighting is unmetered due to their fixed l ighting system to contractors. Compensation may be energy usage when operated by a photoelectrical g iven based on the average u ptime of a l l lig hts in control, as wel l as the costs associated with providing their contract. This is referred to as performance based conventional meteri ng. maintenance and is used by some j u risdictions for road maintenance and for large private-pu blic partnership The total monthly charg e per light source is equal contracts. to the sum of the facility charge (util ity or customer 6-50 Lighting System Components owned) and the energy charge. Monthly facil ity charges To realize cost savings associated with b u rn schedule incl ude the costs of own i ng, operating, and maintaining cha nges, appropriate utility tariffs may be ava ilable the various l u minaire types and sizes. Month ly energy that allow billing streetlights based on actual, rather charges are based on the energy (kilowatt-hour, kWh) than assu m ed, energy use. This w i l l be especially usage of each l u m inaire. important for adaptive l i g hting scenarios, where the fixture wattage is not a fixed item. It will take a l l parties Month ly energy charges per l u m i na i re a re calculated invo l ved-sta n d a rds using: design professionals, regulators, util ities, and streetlight development organizati ons, system owners-to i mplement these tariffs. [(System wattage) (Total burn hours per year)] I [(1 2 months/year) (1 ,000 W/kW) (streetlight energy rate, $/ kWh)]. 6.1 0.4 Integration and Com missioning. System integration is defined as the process of bringing together the component subsystems to fu nction as one system . 6.1 0.3.7.3 Metered Service. This type of service is T h e system integrator brings together discrete systems provided to m ultiple l ighting systems to which the utilizing a variety of techniq ues such as com puter util ity del ivers cu rrent at a secondary voltage, and networking, enterprise application i ntegration, busi ness to series street lighting systems for which the utility process management, and manual prog ra m ming. fu rnishes constant-current reg u lating transformers. The total bund led service charges are calcu lated using the Commissioning can be defined as the process of ensuring total customer charg e and total energy rate. that all subsystems and components of a streetlight system are designed, i nsta l l ed, tested, operated, and 6.1 0.3.7.4 Meter Accu racy. Uti l ities m a i nta i n strict maintai ned according to the operational user needs requirements for revenue-grade metering to comply of the owner or fi nal client (refer to ANSI/JES LP-8-20, with ANSI metering req u i rements. Some of these Lighting Practice: The Commissioning Process Applied to standards may not a pply to the metering chipset Lighting and Control Systems22). for streetlights and control systems. Similarly, there will need to be some standardization in terms of the For l a rge projects, this process usua l ly com prises frequency and accura cy of power measure ments plann ing, execution, and control of many inspection recorded by network control systems. and test activities on "commissionable objects," such as management stations, data logg ers, streetl i g ht One key point of interest, and h i g h ly touted feature of contro l le rs, circu its, com m u nications i nfrastructure, network controls, is the ability to monitor streetlig ht subsystems, and systems. A project that is wel l planned energy usage. This is an i m p rovement from the from the time of conception g reatly m i n i m izes the g overnment and util ity perspective because flat-rate time and cost of integration and commissioning. It is (non-metered) l oads a re difficult to detect when not important that all stakeholders active i n the i ntegration operating properly. Use of an incorrect bal last factor, and commissioning process com mu n i cate, as many l a m p fai l u res, or daytime-burning l ig hts is often not interdependent project activities have the ability to detected in a flat-rate scenario. slow the start-up activities. The collection and sharing of the energy data from these 6.1 0.4.1 I nteroperability. Interoperability is defined as systems a l l ows the transfer of data collected by the the abil ity of two or more systems or com ponents to streetlight network for monitoring and billing pu rposes. exchange i nformation and use the information that The ANSI Standard for Electronic Data Interchange is has been exchanged (IEEE Standard 24765-201 7, ISO/ a l ready being used for direct access. In addition, the /EC/IEEE Approved Draft International Standard - Systems Smart Grid Energy Services I nterface (ESI) defined by the and Software Engineering - Vocabulary23). This ability of U.S. Department of Commerce and the National Institute diverse systems and their components to work together of Standards and Technology (NIST) could be used. is vital ly i mportant to the performance of the street 6-51 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities l ighting system at every level . It enables i ntegration, 6.1 0.4.3 Compliance vs. Conformance. The definition effective cooperation, and two-way com m u n ication of conformance: a mong the many interconnected elements of the street • Meets a specified standard l ig hting network. Effective interoperabil ity is built on • To claim "conformance" to a sta ndard, the a u nifying framework of interfaces, protocols, and the vendor sha l l at a m i n i m u m satisfy the ma ndatory other consensus standards. These standards fac i litate requirements without violating a ny rules u sefu l i nteractions so that, for exam p l e, "smart" • streetl i g ht systems tel l users how much energy they the ma ndatory req u i rements are still conformant are using and at what cost, providing them with more control over their energy and maintenance resou rces. For example, just because the management station and a field device support the same feature, there is no guarantee that the two wil l be interoperable or interchangeable. Vendors that provide additional featu res beyond • Vendors that replace conforma nt features with proprietary featu res are not conformant The definition of compliance: • Meets a specification (e.g., for a specific project) They could support the same feature but speak different of the OSI Model (see Annex B, Section B.1 1) should be 6.1 0 .4.4 I ntegration with U.S. DOE "Smart G rid" Compliant Systems. Under the U.S. Energy followed. To achieve this goal, designers need to examine Independence and Secu rity Act (EISA) of 2007, the the a rchitecture and data flow levels, and clearly identify Nationa l languages. To achieve interoperability, all seven layers which they are implementing and how. I nstitute of Sta ndards and Tec h n o l ogy (NIST) has the "pri m a ry responsibil ity to coordinate development of a framework that includes protocols I nteroperabil ity scenarios: • a n d model sta ndards for i nformation management If both the management station and the field device to achieve interopera b i l ity of smart g rid devices and su pport a feature (consisti ng of a n u n a m biguous systems . . ." data object), interoperability is provided. • If the management station su pports the feature but the field device does not, the management station can still use other features, and the management station can sti l l interoperate that feature with other devices. • If the terminal device su pports the feature but the management station does not, the feature could be used by a nother (or a futu re) management station. 6.1 0.4.2 Interchangeability. For intercha ngea bility of components or systems, three scenarios exist: • If both systems (and their devices) support a feature that consists of an u na mb i g u ous data object, equi pment is intercha ngeable for the feature. • • The "smart g rid" w i l l be key to national efforts to fu rther energy independence and curb greenhouse gas em issions, and NIST is carryi ng out its responsibilities with a sense of u rgency. With ind ustry, govern ment, and consumer stakeholders, N IST is expediting identification and development of standards critical to achieving a rel iable and robust smart g rid. I ntegration of the street lighting system can be by a simple on/off signa l to the util ity. A significantly more su bstantial smart g rid i nterface is defi ned by N IST as an Energy Services I nterface (ESI), which provides a forecast of bid irectional energy usage and its related cost. 6.1 0.4.5 I ntegration with Intelligent Transportation If new equ ipment supports a feature but the old one Systems. does not, the new equipment is interchangeable transportation systems req u i res compliance with U.S. (meets or exceeds). DOT National Tra nsportation Commu nications for ITS If the old equi pment su pports a feature but the Protocol, particu larly NTCIP 1 2 1 3,21 and other related new equipment does not, the feature w i l l not standards. NTCIP and its dependence on the systems be su pported. In this scenario, the user should engineering process (SEP) a l lows for the development reexa mine whether the feature is actua l ly req uired. of a n u n a m biguous project specification. 6-52 In the U.S., i ntegration with intel l i g ent Lighting System Components In addition, NTCIP com pliance i ncl udes unambiguous defi nition of com m u n ication i nterface objects. These objects can then be deployed to achieve interopera bility and i nterchangeability with other devices, systems, a nd applications resident on the national hig hway network. The U n ited States Federal H i g hway Ad m i n istration (FHWA) and Federal Tra nsportation Agency (FTA) provides fu n d i n g for 13 standa rdized i ntel l ig ent transportation systems applications, including street lighting applications. In order to be eligible for this funding, a project should comply with the city, cou nty or state regional ITS arch itecture plan as approved by FHWA. All regional a rchitectures are req u i red to comply with the particular ITS sta ndards for that application. For street l i g hting applications, the relevant standard is NTCIP 1 2 1 3, Object Definitions for Electrical and Lighting Management Systems (ELMS).21 Additional information on NTCIP can be found in Annex B, Sections B.3 and B.4. 6.1 0.4.6 Integ ration with Building Automation Roadways ca n often exten d onto Systems. geographies managed by private third parties. These include shopping malls, office complexes and gated com m u n ities. Frequently in these insta nces, the facility operator desires to monitor and control the l i g hting and to i ntegrate these fu nctionalities with the facil ity's building automation systems (BAS). A variety of software, hardware and com m u n i cations standards are used in the BAS domain. These include BACNet, LonWorks® technology, and Zig Bee technology. Each standard is described briefly in Annex B (see also ANSI/JES LP-6-20, Lighting Practice: Lighting Control Systems - Properties, Selection, and Specification19). 6-53 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities R E F E R E N C E S FOR CHAPTER 6 1. Transportation Association of Canada. Geometric Design Guide for Canadian Roads. Ottawa: TAC; 1 999. 2. American Association of State Highway and Tra nsportation Officials. 2002 Roadside Design G u ide, 3rd ed. Washington, DC: AASHTO; 2002. 3. Federa l H i g hway Ad ministration. Eva l uation of the I m pact of Spectral Power Distribution on Driver Performa nce. Washington, DC: U.S. Federal Hig hway Adm i nistration; 201 5. (FHWA-H RT-1 5-047). 4. I l l u m i nating Engineering Society. ANSI/I ES LP-4-20 Lighting Practice: Electric Light Sou rces - Properties, Selection, and Specification. New York: I ES; 2020. 5. I l l u m i nating Eng ineering Society. ANSI/I ES LM-79-1 9, Approved Method: Optical and Photometric Measu rements of Solid-State Lighting Prod ucts. New York: I ES; 201 9. 6. CSA G roup. Photometric Performance of Roadway and Street Lighting Lum i na i res. Ottawa: CSA G roup; 201 3. (CAN/CSA C653-1 3). 7. CSA G roup. Performance of H i g h mast Lumi naires for Roadway Lig hti ng. Ottawa: CSA G ro u p; 201 3. (CAN/CSA C81 1 ). 8. National Electrical Manufacturers Association. Standards for Roadway and Area Lighting Equipment. Arlington, Virg.: N EMA. (ANSI C 1 36 Series). Onl ine: http://www.nema.org/Tech nical/Pages/ANSl-C1 36-Series-Standards-for­ Roadway-and-Area-Lighting-Eq u i p ment.aspx. (Accessed 2021 J u n 25). 9. National Electrical Manufacturers Association. ANSI C 1 36.3 1 -201 0, American National Standard for Roadway and Area Lighting Equ ipment - Luminaire Vibration. Arlington, Virg.: N EMA; 201 0. 1 0. National Electrical Manufacturers Association. ANSI C 1 36.25-2013, American National Standard for Roadway and Area Lighting Equ ipment - I n g ress Projection for Lu minaire Enclosures. Arli ngton, Virg.: N EMA; 201 3. 1 1 . Manual de l l u m i naci6n Vial: Carreteras, Boulevares, Entronques, Viaductos, Passos a Desnivel y Tu neles. Secretarfa de Comu niaciones y Transportes; 201 5. Onl ine: www.sct.gob.mx/fileadmi n/DireccionesGrales/DGST/ Manua l es/Man u a l_il u m i nacion/Manual_de_ l l u m inacion_Via l_201 5.pdf. (Accessed 2021 J u n 25). 1 2. National Fire Protection Association. N F PA 70, National Electrical Code. Washington, DC: NFPA; 201 7. 1 3 . Norma Oficial Mexicana. l nsta laciones Electricas, Util izaci6n; 201 2. (NOM-001 -SE DE-20 1 2). O n l i ne: http://dof.gob. mx/nota_deta l le.php?codigo=5280607&fecha=29/1 1 /201 2. (Accessed 2021 J u n 25). 14. CSA G ro u p. Canadian E lectrical Code Book, 23rd ed. Ottawa: CSA G roup; 201 6. 15. American Association of State H i g hway and Tra nsportation Officials (AASHTO). LRFD Specifications for Structural Supports for Hig hway Sig ns, Lum ina ires, and Traffic Signals. Washington, DC: AASHTO; 201 5, rev 2020. 1 6. CSA G roup. Canadian Hig hway Bridge Design Code. Ottawa: CSA G ro u p; 2000. (CAN/CSA-S6-00). 1 7. Europea n Centre for Sta ndardization (CEN.) Passive Safety of Su pport Structures for Road Equipment; 2003. (EN1 2767). 1 8. American Association of State and Hig hway Tra nsportation Officials. GL-7, Roadway Lighting Design G u ide, 7th ed. Washington, DC: AASHTO; 201 8. 6-54 Lighting System Components A D D I T I O N A L R E FE R E N C E S FOR CHAPTER 6 1 9. I l l u m i nating Engineering Society. ANSl/IES LP-6-20, Lighting Practice: Lighting Control Systems - Properties, Selection, and Specification. New York: I ES; 2020. 20. Federa l H i g hway Ad ministration. FHWA H RT-1 4-050, G u ideli nes for the I mplementation of Reduced Lighting on Roadways. Washington, DC: FHWA; Jun 2014. 21 . Federa l H i g hway Ad ministration. FHWA H RT-1 4-05 1 , Desi g n Criteria for Adaptive Roadway Lig hti ng. Washington, DC: FHWA; Jul 2014. 22. I l l u m i nating Engineering Society. ANSI/I ES LP-8-20, Lighting Practice: The Comm issioning Process Appl ied to Lighting and Control Systems. New York: I ES; 2020. 23. Institute of Electrical and Electronics Engineers. IEEE Computer Society. ISO/I EC/IEEE Approved Draft International Standard - Systems and Software Engineering - Vocabula ry. New York: I EEE; 201 7. (ISO/IEC/I EEE 24765-201 7). 6-55 Sta n d a rds and Codes Cha pter 7 CO N T E N TS 7.1 7.2 7.3 Local, Regional, and National Codes . . . . . . . . 7-1 Origins of Standards . . . . . . . . . . . . . . . . . . . . . . . 7-1 North American Standards Organizations . . . 7-2 7.3 . 1 Mexican Organizations . . . . . . . . . . . . . . 7-4 M u ltinational Organizations . . . . . . . . . 7-4 7.3.4. 1 Canadian Organizations . . . . . . . . . . . . . 7-2 7.3 . 1 . 1 (cUL) . . . . . . . . . . . . . . . . . . . . . . . . . 7-4 7.3.4.2 U.S. Organizations . . . . . . . . . . . . . . . . . . . 7-3 7.3.2. 1 Ame rican National National Electrical Man ufacturers Association (N EMA) . . . . . . . . . . 7-4 7.3.2.3 7.3.4.3 International Organ ization for Standard ization (ISO) . . . . . 7-5 7.3.4.4 International E l ectrotech n i ca l Commis sion (IEC) . . . . . . . . . . . . 7-5 American Society for Testing and Materials International (ASTM) . .7-4 7.3 .2.4 Institute of Electrical and Electronics Engi neers (IEEE) . . 7-5 Standards I n stitute (A NSI) . . . . 7-3 7.3.2.2 U n derwriters' Laboratories Inc. ( U L) and U L of Canada Inc. CSA G ro u p (formerly Canadian Standards Association) . . . . . . . 7-2 7.3.2 7.3.3 7.3.4 U.S. Nati onal Fire Protecti o n Association ( N F PA) . . . . . . . . . . . 7-4 References for Chapter 7 . . . . . . . . . . . . . . . . . . . . . . . .7-6 Chapte r 7 Sta n d a rds and Codes T his cha pter includes information rega rding electrical, testing, and quality control standards and codes commonly used thro u g hout the roadway lighting ind ustry in North America. Lighting designers, and those responsible for reviewing roadway l i g hting desig ns, should have a working knowledge and u ndersta nding of these standards and codes. This cha pter d oes not l ist specific l i g hti ng design 7.2 Orig ins of Standards standards. Various publications from the organizations Depicted in Figure 7-1, t h e sta ndards contin u u m can l isted i n this chapter are referenced in this document. be thought of as stretching from a single or two­ Whi l e this Recommended Practice is i ntended to be party proprietary specification to a fu l l international a standalone guide to roadway l ighting design, it is standard, across the dimension of development time not intended to be a com prehensive treatment of mea s u red i n months to years. Further categorization a l l s u bjects presented. Lighting designers should can be applied rega rding the de facto or de jure legal acquire the va rious reference docu ments prod uced status. Specifications and req u i rements a re defi ned by by the organizations presented below to gain further single or multiple persons, a l l iances or organizations. Often proprietary in natu re, they are q u i ckly developed knowledge and understa nding. to s u pport interconnection and i ntegration of various It is im portant to note that reference materia l s produced by the va rious organizations a re reg u larly updated. Lighting designers should make it a regular practice to review the websites of the organizations l isted below to determine whether their i nformation has been u pdated. devices and systems, usually over a period of months. Allia nces, trade g rou ps, and consortia are groups of entities (and individuals) that recognize the value of a particular technology, and form a formal "interest group" to promote aspects such as the codification of design and marketing of that technology. The differences between an a l l iance and a formal standards g roup lie within both 7.1 Local, Regional, and National Codes Road authorities may differ in their req u i rements for inspection and code com p l iance. In addition, tra nsportation agencies may have their the rules and the work prod ucts. Since any number and bal ance of interested parties can form an allia nce, the rules under which they operate are very broad. own standards-e.g., the AASHTO Roadway Lighting Design - Em Standards G uide- which may differ i n their recom mendations from those presented i n this Recom mended Practice. It is the responsibil ity of the project desig ner to determ ine "' ..... "' JIS � =- � .... ::::::� = .� -= =-"' - the applicable sta ndards and codes that apply to the g iven area, and to fu lly understand and i ncorporate a ny req u i rements from applicable N orth American standards and code organizations. "' .c c: 0 � Interpretation of standards and codes can be a n a rea of contention for the lighting designer. In general, the authority with j u risdiction for enforcing the code or TWo-party di!/acta Alliance User'sGroup National deJure International standard typical ly has the responsibil ity for making Figure 7-1 . The standards continuum. (©Smart Grid interpretations. I nteroperability Pa nel 2014) 7-1 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities development standard i ncludes i nteroperability tests or guidelines, organizations (SDOs) operate under similar rules and a technology could only be stated to be in com pliance In contrast to a l liances, sta ndards governance principles worldwide. In general terms, the with that standard. For confirmation of i nteroperability members ofthe committees doing the actual development of the va rious system components, a comprehensive work are limited by antitrust rules or laws from engaging test plan should be developed (see Chapter 6, Section in anticompetitive behavior such as market division and 6.1 0.4.1 for additional i nformation). pricing discussions. In addition, intellectual property is treated as a potential source for standards language and Depending on the project-specific user needs that have requires disclosure by the holder. A clear distinction from been defined for a l i g hting control system, proprietary an alliance or users group is that strict control is maintained or sta n d a rd ized com m u nications solutions may be of the candidate voter pool for balloting, to ensure a selected. measure of fairness and balance. As an example, the American National Standards Institute (ANSI) has three categories: producer, user, and general interest, and for 7.3 North American Standards Organizations balloting purposes no single category can exceed one half 7.3.1 Canadian Organizations. of eligible voters (for non-safety related standards). may 7.3.1 .1 CSA G roup (formerly Canadian Sta ndards actu a l ly begin as de facto "standa rds"; i.e., enough Association). CSA Group is a non-profit, membership­ Forma l sta n d a rds (a nd many specifications) com m o n a l ity among enough prod ucers to call the based product, a pproach, or protocol "standard ." Beyond this, government, and consu mers in Canada and the global SDOs actually author de jure sta ndards-those that are ma rketplace.1 association serving b u s i ness, i n d u stry, codified in a ma nner s i m i l a r to laws. Given the careful attention to balloting bala nce, open ru les, and open As a solutions oriented organization, the CSA G roup participation, sta ndards may be adopted in place of works in Canada and a round the world to develop laws in certai n jurisdictions. standards that address real needs, such as enhancing public safety and hea lth, advancing the q ua l ity of Table 7 1 summarizes the standards conti n u u m with life, assisting in preservation of the environment, and respect to the elements described above. fac i l itating trade. Standards meet the goal of creating a common basic The application of the CSA G ro u p with respect to u nderstanding of a technology. Unless the scope of a roadway l i g hting is covered in Chapter 5 - - The Table 7-1 . De Facto and de Jure Standards de facto dejure Level Defined By Recognized Example Timeframe Proprietary One or two vendors or users Market domina nce, File fo rmats, Months ma rket acceptance A Pis Consortium, Group of vendors and/ Members of the allia nce, ASH RAE, EIA, Allia nce, Trade or users representing a n consortium, or trade group Zig Bee, TALQ Group ind ustry or ma rket National National standards body Within one country ANSI, CSA, or group of countries U L, NTCIP, Months or Yea rs Years AAS HTO, ITE I nternational International standards body Worldwide I EC, ISO, ITU, DALI Source: IES RLC member Jim Frazer. 7-2 Years Standards and Codes Planning and Design Process and Chapter 6 System equipment having ratings of 600 V and less Components. Part I of the Canadian Electrical Code intended to be i nsta l led in com mercia l or industrial (CEC), entitled Electrical Installation Code, covers design non hazardous locations i n accordance with the and installation of electrical systems. Part I I of the rules of the CEC, Part I. This standard appl ies to - CEC, Standards for the Construction, Testing and Making poles used for the support of l ighting equipment of Electrical Equipment, covers the req u i rements for such as l u m inaires, electric signs, and traffic signals. electrica l manufacturers. The poles may a lso serve as supports for aerial All e lectrical equipment in Canada will typical ly be equipment and, i n the case of concrete or metal conductors used to su pply power to the lighting required to conform to the CEC Part II and sha l l bea r poles, provide wire ways for conductors entering a label from a test facil ity accredited by the Standards the poles. This sta ndard applies to the el ectrical Association of Canada, verifyi ng that the product meets features of poles as wel l as to the mechanica l or exceeds CSA G roup sta ndards. Each city or province strength aspects and abi lity t o support their design may have its own electrical a mendments to the CEC Part loads. This sta ndard does not a pply to the erection I, which wil l typica lly be issued by the city or provincial of poles or the i nstal lation of accessories on site. e lectrica l inspection agency. • GSA G22.2 No. 250, Luminaires. This standard applies to l u m inaires for use i n nonhaza rdous locations that CSA Group codes and standards that are frequently of 600 V nom ina l or less between conductors, in used in roadway l ighting include: • a re i ntended for i nsta l l ation on branch circu its CAN/CSA C6, Canadian Highway Bridge Design Code. accordance with the CEC, Part I . This code applies to the design, evaluation, and structural rehabilitation design of fixed and movable 7.3.2 U.S. Organizations. highway bridges in Canada. There is no limit on span • length, but the provisions do not necessarily cover 7.3.2.1 American National Standards Institute (ANSI). The all aspects of design for every type of long-span American National Standards Institute (ANSl)2 is a private, bridge. Provisions are a lso included for the design non-profit organization that oversees the development of pedestrian bridges, retaining walls, barriers, and of voluntary consensus standards for products, services, highway accessory supports of a structural nature, processes, systems, and personnel in the U.S. ANSI also such as l ight poles and sign support structures. coordinates U.S. standards with international standards so CSA C653, Optical Efficiency of Roadway Luminaires. that American products can be used worldwide.3 This code section esta bl ishes minimum performance sta ndards for cobra-head and high­ mast style roadway l u m i naires • CAN/CSA C81 1 -98, Performance of Highmast Luminaires for Roadway Lighting. This standard covers the design of l u m inaire optical systems for high-mast l ighti ng. • • CSA C22.2 No. ANSI accredits standards that are developed by other standards development organizations (SDOs), including the I ES. This helps to ensure consistency i n characteristics and performa nce for products, and consistency in terms and defi nitions in sta ndards documents.3 As many l i g hting products used throughout North O-M91, General Requirements. America a re produced in the U nited States, ANSI This sta ndard covers defi nitions, construction standards are commonly referenced. Where a n ANSI req u i re ments, marking, and tests of a genera l specification is referenced for a given product or product nature that a r e applicable t o a l l, or several, o f t h e com ponent, a copy of the specification can be obtai ned individ ual standards o f Part I I o f t h i s Code. from ANSI by referencing the ANSI specification n u m ber. GSA G22.2 No. 206, Lighting Poles. This standard applies to freesta nding poles of ferrous meta l, ANSI specifications for roadway l i g hting com ponents a l u m i n u m, are m ost commonly used for l a m ps and l u m i na i re concrete, or wood, and to their accessories, for use i n the su pport of l ighting components. 7-3 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 7.3.2.2 National Electrical Man ufacturers Association fu rthering [its] mission. N FPA membership tota ls more (NEMA). N EMA, created in 1 926 by the merger of the than 60,000 i ndivid uals around the world. Its mission E lectric Power C l u b and the Associated Manufacturers is to help save l ives and reduce loss with information, of E lectrical knowledge, and passion.6 Suppl ies, provides a for u m for the standardization of electrical e q u i pment, enabling consu mers to select from a ra nge of safe, effective, a nd The N F PA is the sponsoring organ ization for the compatible electrical prod ucts.4 National Electrical Code (N EC), the pri mary electrical code for i nsta l lation of electrica l equipment in the The organization has made nu merous contri butions U n i ted States. The N EC is a g uidel ine for electricians, to the e l ectrical ind ustry by shaping p u blic policy electrical contractors, engi neers, and inspectors. development. It a lso operates as a central confidential agency for gathering, compi l i ng and analyzing market statistics and economics data. The association promotes safety in the manufacture and 7.3.3 Mexican Organizations. There are several codes that deal with Roadway Lighting in Mexico: • use of electrica l products. It provides information to the fi le/1 8 1 651/NOM_013_ENER_2013.pdf) media and the p u bl ic and represents industry interests in new and developing technolog ies. • Specifical ly for the application of LED l u minaires in exteriors (incl uding roadway): NOM-031-ENER. (https://www.gob.mx/cms/u pl oads/attachment/ N EMA sta ndards are commonly used throughout North file/1 8 1 671/NOM_031_ENER_2012.pdf) America. In the l i g hting i n d u stry, N EMA sta ndards are typica l ly used for l u m inaires, electrical boxes, and For energy efficiency: NOM-01 3-ENER. (https://www.gob.mx/cms/u pl oads/attachment/ • The National Program for Roadway Lighting of the CON UEE (Co m m ission for the Efficient Use electrica l panels. of Electric Energy): https://www.gob.mx/cms/ 7.3.2.3 American Society for Testing and Materials uploads/attachment/fi le/9 1 781 /Presentacion_ I nternational (ASTM). ASTM is composed of a large ProyectoNaciona l .pdf nu m ber of technical sta ndards-writing comm ittees, with over 1 2,000 ASTM standards operating g l obally. Together these comm ittees have publ ished thousands of sta ndard specifications, tests, practices, g uides, and definitions for materials, prod ucts, systems, and services.5 Among ASTM sta ndards a re those dea l i ng with meta ls, flammability, chemical products, l u b ricants, fossi l fuels, textiles, paints, plastics, ru bber, pipes, forensic sciences, • The Handbook (or Code) from the Federal Secretary of Transportation (SCT): www.sct.gob. mx/fileadmi n/DireccionesGrales/DGST/Manuales/ Manual_i l u m inacion/Manual de l l u minacion Vial_201 5.pdf There is also a general cha pter in the NOM-001 -ENER, which is the eq u ivalent to the U.S. National Electric Code, but it does not get i nto specifics. electronics, energy, and medical devices. 7.3.4 Multinational Organizations. ASTM sta ndards a re com m o n l y referenced for the testing of l ight poles as well as the concrete and soils 7.3.4.1 Underwriters' Laboratories I nc. (UL) and UL of used for foundations for pole structures. Canada I nc. (cUL). U nderwriters' Laboratories (UL) is an independent, non-profit product-safety testing and 7.3.2.4 U.S. National Fire Protection Association certification organization. It was founded in the U nited (NFPA). The N F PA delivers information and knowledge States in 1 894 (as the U nderwriters' Electrical B u reau).7 throug h more than 300 consensus codes and standards, Electrical eq u i pment manufactured and used in the U.S. research, training, education, outreach, and advocacy, is typica l ly req uired to be U L l isted and, as such, to bear and by partnering with others who share an interest i n a UL label. 7-4 Standards and Codes U nderwriters Laboratories of Canada (cUL)8 is also a n independent, non-profit product-safety testing and certification org a n ization, a lso fou nded i n 1 894. I n Canada, the cUL label ind icates that prod ucts have been tested in accordance with Canadian sta ndards. 7.3.4.2 I nstitute of Electrical and Electronics Engineers (IEEE). An international standards organization with more than 420,000 members in over 1 60 countries, IEEE "is the trusted 'voice' for engi neering, com puting, and technology information around the g lobe." It is known for its publications, conferences, technology standards, and professional and education activities.9 7.3.4.3 I nternational Organization for Standardization (ISO). The I nternational Organization for Standardization (ISO) is the world's largest developer of standards, with a membership of 1 63 national standards bodies.1 0 North American su ppliers of a wide range of prod ucts who wish to sel l i nternatio n a l ly may be requ i red to obta in and ma intain ISO certification. In N orth America, ISO certification wou l d typica l ly apply to man ufacturing processes defi ning a level of Qua l ity Control and Qual ity I m provement with the man ufactu rer's org a n ization. Owners of roadway lighting systems may require that the products specified be manufactu red u nder specific ISO certifications to ensure that prod uction processes are developed and fol lowed. 7.3.4.3 I nternational Electrotechnical Commission (I EC). The I EC, founded in 1 906, is a Europe-based organization that prepares and publishes i nternational sta ndards for all e lectrical, electronic, and related matters, such as the assessment of conformity to standards. The I EC provides a platform to companies, ind ustries and governments for meeting, discussing and developing the i nternational standards they req uire. All I EC International Standards a re fu lly consensus based and represent the needs of key stakeholders of every nation participating in IEC work. Every member cou ntry, no matter how large or small, has one vote and a say in what goes i nto a n IEC I nternational Standard.11 7-5 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities R E F E R E N C E S FOR CHAPTER 7 1. CSA G roup (formerly Canadian Standards Association) website (codes and sta ndards): http://www.csagrou p.org/ codes-standards/. (Accessed 2021 Feb 24). 2. American National Standards Institute website: www.a nsi.org. (Accessed 2021 Feb 24). 3. https://en.wikiped ia.org/wiki/American_National_Standards_l nstitute. (Accessed 2021 Feb 24). 4. National Electrical Manufacturers Association website: www.nema.org/. (Accessed 2021 Feb 24). 5. American Society for Testing and Materials International website: www.iso.org/home.ht m l . (Accessed 2021 Feb 24). 6. National Fire Protection Association website: http://www.nfpa.org/overview. (Accessed 2021 Feb 24). 7. Underwriters' Laboratories website: http://www.u l .com/. (Accessed 2021 Feb 24). 8. Canada Underwriters' Laboratories website: http://www.ul.com/. (Accessed 2021 F e b 24). 9. Institute of Electrical and Electronics Engineers website: www.ieee.org/a bout/index.html. (Accessed 2021 Feb 24). 1 0. International Organ ization for Standardization website: www.iso.org/home.html. (Accessed 2021 Feb 24). 1 1 . International Electrotechnical Comm ission website: http://www.iec.ch/. (Accessed 2021 Feb 24). 7-6 Com p uter Appl ications Cha pter 8 CO N T E N TS 8.1 8.2 Overview 8-1 Limitations of Computer Calculations . . . . . . . 8-1 8.3 8.4 Basic Luminance Ca lculations . . . . . . . . . . . . . . 8-1 Complex Roadway Calcu lations . . . . . . . . . . . .8-3 8.5 Typical llluminance Application . . . . . . . . . . . .8-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.6 Calculated Digital Renderi ngs . . . . . . . . . . . . . 8-4 8.6.1 The Rendering Process . . . . . . . . . . . . . . 8-4 8.6.2 Uses for Renderings . . . . . . . . . . . . . . . . . 8-5 8.6.3 Limitations of Renderings . . . . . . . . . . 8-5 . Chapter 8 Com p uter Appl ications T his chapter conta ins an overview of the computer progra m s currently ava ilable for designing roadway lighting. It also contains examples of the types of output genera l l y expected from the programs. Comparisons of computer prog ra ms a re not in the scope of this docu ment. The type of application (e.g., street, intersection, tunnel) can provide important information, such as roadway will dictate whether illuminance or luminance calculations alignment or stationing locations, curb l ines, and are appropriate. The IES has adopted luminance as the property lines. This information helps to provide the primary metric for straight roadway and tunnel lighting interpreter of the calculation with the location and calculations. The orientation of the calculation area on the site. llluminance method remains the calculation method for other applications, such as parking lots, intersections, and walkways and bikeways. Computer lighting calculation programs are suitable for determining 8.2 Limitations of Computer Calcu lations compliance with luminance or illuminance criteria. Com puters a re the prime calcu lation tool for roadway l ig hting. Computer programs' a bi l ity to represent actual cond itions is l i m ited; i.e., the user of a computer prog ra m 8.1 Overview needs to realize that the degree of precision possible There a re fou r basic elements used for computer with a computer calcu lation may be beyond what can roadway calcu lations: be demonstrated i n the field. There a re many variables • • Luminaires. Luminaire intensity distributions are working to ensure differences between the calculated contained in photometric files. These files may be in environ ment and the actual conditions (BRDFs; which various formats: IES (*.ies), CIBSE (*.cib,*.tml,*.cls, *.cc), or represent road surface reflection characteristics, a re a EULUMDAT (*.ldt, *.exl). The files contain the luminous prime example, even on stra i g ht roads). The true value intensity distributions. Luminaires are placed and for roadway computer calculations is in the com parison oriented on a site plan to model the actual conditions. of a lternative lig hting proposals. Val ues measu red i n the Area for the calculation. Luminous fl ux to an a rea is determined in order to calcu late the l u mina nce fiel d w i l l vary depending on how closely the modeled cond itions represent the actua l conditions. or illuminance. The calcu lation area may be defined using a specified shape, or popu lated with discrete ca lculation points representing smaller a reas. The density of the calculation poi nts depends on the metric and is specified in the appropriate standard. In this Recommended Practice, point spacing is found i n Chapter 3 - Calculations. With regard to roadway applications, for l u minance calcu lations the road su rface type is specified as one of four roadway pavement categories. Each su rface type has specific bidirectional reflectance properties. • Other surfaces and objects. Surfaces and objects can block and/or reflect light and can affect the calculated results by either reflecting light or obstructing it. • Background. Background images or drawings do not influence the calculated resu lts. The background 8.3 Basic Luminance Calculations Roa dway l u m ina nce calcu lations, described in Chapter 3, a re for straight roads because of the assumed position and d i rection of view of the observer (driver). The calculation g rid config u ration is for one l u minaire cycle and assumes a consistent n u m ber of la nes, l u m i naire mounting heig hts, and pole setbacks. Figure 8-1 shows a typica l l u m i na nce calcu lation for one l u minaire cycle. · Bidirectional reflectance distribution function (BRDF): The ratio of the d ifferential luminance of a ray reflected in a given direction to the differential luminous flux density incident from a given direction that produces it. This distribution function is the basic parameter for describing (geometrically) the reflecting properties of an opaque surface element (negligible internal scattering). Ref. ANS/I/ES LS-7- 21, Lighting Science: Nomenclature and Definitions for Illuminating Engineering; on line: https://www.ies.org/standards/definitions/). 8-1 ANSl/IES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Lumi nance Figure 8-1 . Example of a luminance calculation for a roadway. (Graphic courtesy of Ray Yeager) 8-2 Computer Applications 8.4 Complex Roadway Calculations and various pole heights. It is important to note that the Actual roadway calculations are typical ly more complex. lum inance for the curve is approximated by using straight Roads are often curved and have varying numbers of lanes. ana lysis sections between poles on the curved road. These Poles are often unevenly spaced and may have different are used to approximate the luminance on the curve. heights. The number of fixtures per pole often varies. In short, the basic luminance calculation is not appropriate to adequately design and analyze an actual instal lation. 8.5 Typical l l l u minance Application When analysis of a lighting layout with complexities is l l l u m i na nce required, a computer program that permits accounting for crosswal ks, and parking l ots. Figures 8-3 and 8-4 show a p p l ications include i ntersections, variations is needed. Figure 8-2 illustrates an analysis of a exa mples of i l l u m i nance calculations for a roundabout roadway with a gentle curve, different numbers of lanes, and a parking lot, respectively. Figure 8-2. An example of a more complex roadway system. (Graphic cou rtesy of Ray Yeager) LS- 38808 2 1 0 SMe lser R o u n ol o b o u _J L o c o "t i 1 ( 4 0 . 7 5 £1 Lo}3�r of v (- ' , - o p p r o o c h i n g ol r i v e r 2 1. 179) Figure 8-3. Example o f an illuminance calculation for a roundabout. (Graphic courtesy of Ray Yeager) 8-3 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Figure 8-4. Example of an illuminance calculation for a parking lot. (Graphic courtesy of Ray Yeager) objects included. The creation of the model a lso 8.6 Calcu lated Digital Renderings Lighting software is ava i lable with capa b i l ities that req u i res definition of the va rious surfaces, and in extend beyond calcu lating to meet lighting criteria, the case of l u m inaires and other l ight sou rces, the such as calcu lated three-dimensional models of the assig n ment of photometric data . Care m ust be results of a l ighting design. These models can be used taken in the creation of the model to ensure that su rfaces are correctly layered and complete. This to accu rately visualize and present a proposed design. ensures that "light l eaks" and other anomalies do g ra p h i c a l not occ u r when calcu lations and renderings are representations based on t h e data a n d calcu lations undertaken. If objects a re not properly joined, for C a l c u l ated d ig ital re n d e r i n g s a re used i n the desig n. Because the software can help to exam p l e, l ig ht may "leak" i nto the rendered scene commun icate aspects of a design i n a visual manner, the from a n object, source or su rface not norma l ly in results may be more understandable to nontechn ical view in the real world. It is also i mportant to assign individuals. This is i mportant in a world where citizen su rface reflectance val ues as accu rately as possible, g ro u ps, el ected as this wil l affect the calculated results. officials, and other n o n - l i g hting professionals have concerns rega rd ing aesthetics, obtrusive lig ht, and energy use. • Radiosity calculations. O n ce the model is completed, radiosity calcu lations a re performed. I n this step, t h e total l i g hting energy g enerated b y a l l Although a complete review of dig ital renderings is l ig ht sources is calcu lated for every su rface i n the beyond the scope of this document, the fol lowing model. The process takes into account reflection sum mary is provided because the use of renderings is of l i g ht energy from su rfaces. The calculation l i kely to become more common i n the future. process conti nues until all em itted and reflected 8.6.1 The Rendering Process. calcu lation is a rendered environment that may be l ight is accounted for. The result of the radiosity • 8-4 Creating the model. The first step is to create navigated about to view the results from different a th ree-d i mensiona l model in a 30 a n imation, perspectives. I ndividual i mages may be captured modeling, and rendering prog ra m with all pertinent for sharing with others. Computer Applications • Ray tracing. Depen ding on the software, ray in design, and to explain issues to those with l ittle or no tracing may be performed instead of or fol lowing knowledge of lighting desi g n . For example, by adding a radiosity view "ceiling" to a scene, desig ners can observe antici pated dependent. Therefore, prior to performing the ray­ c a l c u lations. Ray tracing is sky glow effects. Another use m ig ht be to identify at a trace calculation, the operator first selects a point g lance areas that m ig ht be over- or u nder- i l l u m inated, of view (POV) from which to create the rendering. including those without a calculation g rid assigned. The selection of the view is s i m i l a r to setting Other issues, such as the visibility of pedestrians, sig ns, up a camera to take a picture. The view is then or other objects, a re i nstantly obvious from a calculated calcu lated, and each pixel in the scene is rendered. dig ital rendering. Each view defi ned m u st be calcu lated separately in ray traci ng, although multiple views ca n be 8.6.3 Limitations of Renderings. Some aspects of "stitched" together to form animated scenes. Ray design, such as veiling l u m i nance, cannot be shown in tracing is computer-processor dependent; detai led calcu lated dig ita I renderings due to the lim itations of the scenes may take several hours to render, depending process. In addition, while correlated color temperature mainly on the complexity of the model, the n u m ber may be shown for light sou rces, and a l most any color of light sou rces, com puter speed, and the desired can be assig ned to the va rious su rfaces i n the model, resol ution of the fi nal output. A fin ished model an accu rate comparison of color rendering effects from is shown i n Figure 8-5. The calcu lated, rendered light sou rces with d ifferent spectral content cannot model may be presented in various formats, be d isplayed on the computer screen because of the including those for printed or projected media. l i mitations of RGB computer mon itors. Other effects 8.6.2 Uses for Renderings. Digital renderings are useful that d o not mimic rea l ity and m ig ht confuse those to exam i ne l i g hting issues that are difficu lt to visual ize viewing the renderi ng. such as the depiction of sky g low req u i re techniq ues Figure 8-5. Example of a three-dimensional rendering for a street, sidewalks, and intersection, with vehicles, pedestrians, and trees present. (Calcu lated digital rendering cou rtesy of WSP) 8-5 M a i ntena nce a nd Operations Cha pter 9 CO N T E N TS 9.1 Safety 9. 1 . 1 9.2 9.3 9.4 9.5 9.6 9.7 9-1 9.7.2 I nformation Gatheri ng . . . . . . . . . . . . . 9-1 4 Funda menta l Principles . . . . . . . . . . . . . 9-1 9.7.3 Troubleshooting LED Luminaires . . . 9-1 4 9.7.4 Troubleshooting HPS Luminaires . . . 9-1 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9. 1 .2 Procedures Before Beg i n n i ng Work . . 9-1 9. 1 .3 Electrica l . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2 9.1 .4 Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2 Maintenance Management System Guidelines . . . . . . . . . . . . . . . . . . . . . . . .9-1 6 9. 1 .5 Traffic Control . . . . . . . . . . . . . . . . . . . . . . . 9-2 9.8. 1 9.1 .6 Environmental Protection and Health and Safety Hazards . . . . . . . . . . . 9-2 9.8.2 Req u i rements . . . . . . . . . . . . . . . . . . . . . . 9-1 7 9. 1 .7 Contact Voltage . . . . . . . . . . . . . . . . . . . . . 9-2 9.8.3 Operations and Asset Management . 9.8 Inspections, Patrols, and Public Reporting . . . . . . . . . . . . . . . 9-1 6 Luminaires and Accessories . . . . . . . . . . . . . . . 9-4 via Networked Systems . . . . . . . . . . . . . 9-1 8 9.9 Light Source Failure 9-1 9 9.2.1 Light Sou rce Life . . . . . . . . . . . . . . . . . . . 9-4 9.2.2 Light Sou rce Lumen Depreciation . . . 9-4 9.9. 1 Light Emitting Diode (LED) Fai l u re . . 9-1 9 9.9.2 H ig h I ntensity Discharge . 9.2.3 Lumen Dirt Depreciation . . . . . . . . . . . . 9-4 9.2.4 Leveling and Align ment . . . . . . . . . . . . . 9-5 9.2.5 Controls . . . . . . . . . . . . . . . . . . . . . . . . . . 9-5 9.2.6 Line Voltage . . . . . . . . . . . . . . . . . . . . . . . . 9-5 9.2.7 Obstruction of Light and 9.9.4 Photocontrols by Foliage . . . . . . . . . . . . 9-6 9.9.5 . Lam p Fai l u re . . . . . . . . . . . . . . . . . . . . . . . 9-1 9 9.9.3 . Pa int or Coating . . . . . . . . . . . . . . . . . . . . . 9-8 9.3.2 Vibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-9 Low Pressure Sod i u m (LPS) Lam p Fai l u re . . . . . . . . . . . . . . . . . . . . . . . 9-20 Poles and Accessories . . . . . . . . . . . . . . . . . . . . . 9-8 9.3.1 . . . . • . . . . . . . . . . . . . . . . . . I nca ndescent La m p Fai l u re . . . . . . . . . 9-20 Basic Relamping Practices and Choices . . . . . . . . . . . . . . . . . . . . . . . . 9-20 9.1 0 9.1 1 Relamping With LED Retrofit lamps . . . . . . . 9-21 Disposa l of Components . . . . . . . . . . . . . . . . . 9-21 Maintenance of Conventional 9.1 2 New Light Sources a nd Components . . . . . . 9-22 Lighting Systems . . . . . . . . . . . . . . . . . . . . . . . . . 9-9 9.1 3 Economics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-22 9.4. 1 Preventive Maintena nce . . . . . . . . . . . . . 9-9 9. 1 3. 1 9.4.2 Light Loss Factors . . . . . . . . . . . . . . . . . . 9-22 Corrective Maintenance . . . . . . . . . . . . 9-1 0 9.1 3.2 Record Keeping . . . . . . . . . . . . . . . . . . . . 9-22 Mai ntenance of Hig h-Mast Lighting Systems . . . . . . . . . . . . . . . . . . . . . . . . .9-1 0 9.1 3.3 Group Versus Spot Relamping . . . . . 9-22 9.1 3.4 Maintenance Budgets . . . . . . . . . . . . . 9-23 9.5.1 Preventive Maintena nce . . . . . . . . . . . . 9-1 0 9.1 3.5 Energy Costs . . . . . . . . . . . . . . . . . . . . . . . 9-23 9.5.2 Corrective Maintenance . . . . . . . . . . . . 9-1 1 9.14 Maintenance of Tunnel Lighting Systems . . 9-1 1 9.1 5 9.6. 1 Preventive Maintena nce . . . . . . . . . . . . 9-1 1 9.6.2 Corrective Maintenance . . . . . . . . . . . . 9-1 3 Troubleshooting, Repair, and Replacement. . 9-14 9.7.1 Procedu res for N ight Patrol Service . . . 9-1 4 . . Methods of Contracting . . . . . . . . . . . . . . . . . . 9-23 Equipment Testing . . . . . . . . . . . . . . . . . . . . . . 9-24 Add itional Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-25 References for Chapter 9 9-25 . • . . . • . . . . . . . . . . . . . . . . . Chapte r 9 M a i ntena nce a n d O perations T he primary pu rpose of roadway l i g hting is to provide a safe nighttime environment for vehicular and pedestrian traffic. For a l ig hting system to operate at maxi mum effectiveness, the lighting system mai ntenance sho u l d be considered and included d u ring the system design process. Once a system has been desig ned and insta l led, proper mai ntenance then becomes essential to the rel iability and continued high performance of the roadway lighting system. Like any lighting system, a roadway l i g hting system is 9.1 .1 Fundamental Principles. Preventing accidents subject to performance degradations. Exposure to the during a maintenance activity is vitally im portant. Each u nfriendly outdoor environment makes ti mely system person carryi ng out mai ntenance work should take maintenance of paramount im portance. If a roadway personal responsibil ity for his or her own safety as well l ighting system is not properly maintained, safety may as the safety of others. be compromised, and deferred mai ntenance w i l l usua l l y mean i ncreased costs. Mai ntenance work sites should be ca refu lly checked to The changing maintenance cond itions due to work staging make sure that the traffic controls are cha nged to reflect cost-benefit relation s h i p of proper system maintenance should be determined by the i nd ividual owner based on the needs for, and comm itment to, system reliability. The pu rpose of this g uide is to provide the designer and owner with an understa n d i n g of maintenance problems and procedures so that sound decisions can be made on mai ntenance practices that are appropriate for a roadway lighting system . (Note: and progress, or if a n i mmediate improvement to the traffic control is needed . 9.1 .2 Procedures Before Beginning Work. type of maintenance work on the roadway: • • that may be affected by the maintenance activities. • Provide advice to the public of the works planned or in progress, as appropriate, through the local media. 9.1 Safety • Ensure that adequate signs, barricades, and ma rkers are taken to the mai ntenance work site to provide roadway systems, it is essential to ensure that basic appropriate protection. safety rules are observed. The safety of the mai ntenance workers and their equ ipment is of extreme im porta nce, Notify the pol ice, fire department, and appropriate road authority, if req uired, and a ny other agencies Intensity Discharge Lamp Failure.) In carrying out any maintena nce operation on the Obta i n the necessary approvals and/or permits from the road a uthority. Material on the maintenance issues specific to legacy H I D systems can be found in Section 9.9.2 High The following steps should be taken before beginning any • Ensure that the warning devices can be properly placed to protect the mai ntenance work site, and and care should be exercised in ensuring the safety of the traveling public while proceeding through a that trees, shru bs, or other signs do not obstruct roadway l ig hting mai ntenance site. them. • properly sepa rated. Al l work performed d u ring a maintenance operation shal l comply with all of the federal, state, provincial, and • Fol l ow safe work practices d u ring i n c le ment weather. local laws and by-laws perta i n i ng to the work, as well as by the applicable electrica l safety code and the latest Ensure that vehicle and pedestrian movements a re • If night protection is req u i red, ensure that the issue of U L, CSA, or equ iva lent sta ndards pertinent to appropriate devices a re available and that they are the work. in g ood condition. 9-1 ANSl/IES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 9.1 .3 Electrical. No worker, other tha n q ua l ified operated where the operator's view of the i ntended personnel, sho u l d connect, maintain, or mod ify electrical path of travel of a ny part of it or its load is obstructed equipment or installations. (Refer to regional health and or where it is in a location in which a person may be safety codes for "q ualified person nel" definitions.) Every endangered by a ny part of it or its load, u nless the reasonable precaution, including the use of personal operator is assisted by a signaler. protective equ ipment (PPE), should be taken to prevent a hazard to a worker from an energ ized electrical An operator of a vehicle, machi ne, equipment, crane (or conductor or piece of equi pment. similar hoisting device), shovel, or backhoe (or similar excavating machine) who is req u i red to be assisted by Electrica l equipment, con d u ctors, and i n s u lating a signa ler should operate it as d i rected by the signaler. materials should be suitable for their intended use and should be installed, maintai ned, modified, and The signa ler should be a qualified worker and should operated so as to not pose a hazard to a worker. not perform other work while acting as a signaler. Where appropriate, the power supply to e lectrica l The signaler should com m u n i cate with the operator by i nsta l lations, equipment, or cond u ctors should be means of a teleco m m u n i cations system or, where visual disconnected, locked out of service, and tagged before signals a re clearly visible to the operator, by means of any work is done. Electrical equi pment not con nected prearranged visual signals. to the l u m i n a i re (e.g., pole-mou nted ca meras, l u m i n a i res) 9.1 .5 Traffic Control. It is recognized that, even with should be rendered safe for people to work within close good signing and advance warning devices, the set com m u n ications a ntennas, a d d itional proximity of. up or removal of traffic control (e.g., lane closures) on highways i nevitably i nvolves an element of risk due 9.1 .4 Equipment. to factors such as d river inattentiveness or excessive veh icle speeds. There a re risks for the traffic control 9.1 .4.1 General. All vehicles, machi nery, tools, and equ ipment sho u l d be maintai ned i n a condition such workers, risks for the operators of buffer vehicles (if a p p licable), and risks for the motorists. that they d o not endanger mai ntenance workers or the public. No vehicle, machi ne, tool, or piece of equipment should be used if it is defective, hazardous, u nder repa ir, 9.1 .6 Environmental Protection and Health and or being serviced. Safety Hazards. No worker should operate a vehicle un less that worker 9.1 .6.1 Environmental Protection. is qualified to operate the vehicle and has a license to mai ntenance work, and in the hand l i ng of materials In carrying out operate that vehicle on the highway. A worker who is either used d u ring the maintenance activity or d isposed not qualified or licensed may operate a vehicle provided of after the mai ntenance activity is completed, the the worker is being i nstructed in the operation of the workers should com p ly with all a pplicable reg u lations. vehicle and is accompa nied by a person who is q u a lified a n d l icensed to operate the vehicle. 9.1 .6.2 Health and Safety Hazards. Mod ification of equi pment should not occur without activity the workers should meet all of the health and consu lting the manufactu rer, as this may compromise safety regulations applicable to this type of work. In addition to environmental protection issues, d u ring a maintenance safety. 9.1 .7 Contact Voltage. 9.1 .4.2 Designated Signaler. In the context of roadway No vehicle, machi ne, l i g hting, contact voltage occurs when normally non­ equ ipment, crane (or similar hoisting device), shovel, cu rrent carrying elements of the roadway l i g hting or backhoe (or similar excavating machi ne) should be system (e.g., l u m i n a i re, bracket, pole, hand well, 9-2 Maintenance and Operations mai ntenance hole) become energ ized because of faults with a ground shield and connected to a portable in internal or underg round wiri ng. It is i m portant to driven g round. This removes the user from the recognize that this electrical hazard can occur, and to circuit and shields the device from the effects of have maintenance proced u res and practices in place external sou rces of electric fields, such as overhead that reduce contact voltage risk. distribution l ines. • Contact voltage has many causes, such as deterioration Voltmeters. Voltmeters may be used to detect contact voltage and should be used to verify and i n the dielectric strength of the wire and component measu re the amount of contact voltage once it is insu lation due to age or lack of an equipment-grounding detected. I n order to take a n accu rate measu rement conductor. Other possible causes of contact voltage of contact voltage with a voltmeter, the following a re im proper design, poor i nsta l lation tech n i q ues, are req u i red (a and b) or recommended (c): insufficient maintenance, or damage due to accidents, a. A rel iable ground reference point sha l l be vandalism, or rodents. esta blished b. The test probes sha l l make solid physical contact 9.1 .7.1 Detection of Contact Voltage. Various methods with each surface to be checked and equ ipment may be used to detect contact voltage: • Asset-management system detection. Asset c. A shunt resistor, or a digital voltmeter utilizing a management systems can be used to detect system "low i m peda nce" setting, should be used when faults, including the presence of contact voltage taking the measu rement or leakage current. Alerts are automatical ly sent • from the field to a central management system, 9.1 .7.2 I ncorporating Contact Voltage Detection into prompting dispatching of field repair crews. These Roadway Lighting Maintenance. The development enhanced asset management capabilities provide of a m a i ntena nce sta ndard or practice for contact the means for i mmediate detection of fau lts, thus voltage detection (CVD) should first address a ny legal enabling faster response and repair. a n d regulatory req u i rements regarding contact voltage Mobile electric field detection. This a pproach detection. In some ju risdictions CVD testi ng is specified detects chang es in the a m bient electric fiel d by law or regu lation. In these ju risdictions, CVD testing caused by a n object energized by a n AC cu rrent. is typica lly a routine mai ntenance activity carried out This approach is most effective when the electric independent of other mai ntenance activities. field detector is mou nted on a vehicle. Mobile • electric field detection equipment is ava ilable and Where the owner has d iscretion regard ing CVD testi ng, can be used to quickly su rvey a large a mo u nt of the test i n g cou l d be performed concu rrent with roadway i nfrastructure. This equ ipment is relatively other routine mai ntenance activities, or it could be accu rate and expensive. This method req u i res a performed as part of non-routine maintenance work. In trained technician who can identify variations from the latter case, a standard practice could be considered, background field l evels. sti p u lating that when maintenance personnel a re cal led Handheld detectors. H a ndheld "pen" testers to a site to perform non-routine maintenance work, can be used to detect contact voltage. The user they a re to complete their repairs and then perform holds the device in one hand (preferably a bare CVD testi ng before leaving the site. ha nd) and touches the tip of the sensor to the su rface of the object to be tested. The device wi l l The owner may wish to perform a risk a nalysis to identify indicate a potential for contact voltage if it detects the relative risk associated with different insta l lations in a voltage difference between the sensor tip and order to better determine the degree of CVD testing the user's body that exceeds a pre-set threshold. req u i red. Some of the risk factors to consider are: The device operates on the premise that the user's body provides a virtual (capacitatively coupled) connection to g round. The device can a lso be used • Level of pedestrian a nd/or pet traffic • Accessi ble underg round plant versus i naccessible overhead plant 9-3 ANSl/IES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Amount of conductive plant, such as meta l poles, as when the l u men output reaches 70%, known as L10 d u cts, and hand wel l covers (or a ny specified percentage), of initial output. LED • Age a nd/or condition of the l i g hting system manufacturers usually provide LED l u men mai ntenance • Deterioration or lack of eq u i pment g round • Level of vehicular traffic and infrastructure col l ision • information (see Section 3.1 .6.1.1), but this is not the history • LEDs' rated life. Statistical i nformation on fai l u re rates (e.g., Bso, 810) should be provided for LEDs, in order to obta i n rated life (see a lso Section 3.1 .6.1 .3 Lamp U n-perm itted attachments, both mechanical and Burnout Factor). electrical (e.g., banners, cameras) • Other risk factors ( e.g., rodents, vandalism ) The reader is referred to Section 9.9 for information on the ways that the various l ight sou rces a re l i kely to fail. 9.2.2 Light Source Lumen Depreciation. 9.2 Luminaires and Accessories During Lumi naires wil l provide long-term service if properly a l i g ht sou rce's l ifeti me, its l u men output g radually m a i nta i n e d . the d i m inishes. This g radual red uction i n l ig ht output with rep lacement of broken or fa iled components and burning time is called lamp lumen depreciation (LLD) or accessories. The fol l owing items should be checked on simply lumen depreciation. (See Section 3.1 .6.1.1 for a regular inspection cycle: more information on LLD.) Proper m a i ntenance incl udes • Lumi naire: for proper operation • LED outage: for individ ual or m ultiple LEDs in the array that a re not operating • Va nda l and wildl ife shields, ha rdware, and gaskets: for breakage or corrosion 9.2.3 Lumen Dirt Depreciation. In addition to lamp l u men depreciation over time, d i rt accum ulates on both the i nside and outside of the refractor, on the i nside of the luminaire reflector, and on the lamp. This dirt accumulation is responsi ble for an additional reduction • Luminaire interior: for moisture i n g ress or debris i n l u m i naire light output and is known as luminaire dirt • Luminaire housing: cooling fins for acc u m u lating depreciation (LDD). (For g u ida nce on the calcu lation of bird d roppi ngs, foliage, or other debris, which l u m i naire d i rt depreciation refer to Section 3.1 .6.1 .2). could affect the therm a l management of the LEDs inside the l u minaire; h igher than specified thermal 9.2.3.1 Cleaning Schedu les. Cleaning accessible optica l cond itions can affect the life and lumen output of parts is very i m portant to cou nteract LDD. Factors the LEDs affecti ng the cleaning sched ule are the environment i n • Luminaire filter: as a pplicable for dirt col l ection which t h e l uminaire i s instal led-incl uding the climate, • Lens: for cracks, scratches, or a brasion damage that might be reducing optical c la rity • Electrica l wiring: at the pole base and at a l l connections, for da maged wire insu lation, loose connections, or corrosion; ifthe l u m inaire is opened, the wiring inside the l u m inaire should be checked • Photocontrol : for d i rt accu m u lation, the concentration of suspended particles in the air, and the proximity of fol iage (see Section 9.2.7)-and the l u m i naire desig n. Luminaires that a re insta l led under or near trees could accu mulate tree sap on the lenses, which will affect light tra nsmission. Removing tree sap from lenses made of plastic may req u i re special cleaning solvents that w i l l not damage the p lastic. proper orientation, and proper operation For g ro u p re- l a m ped systems (see Section 9.13.3), the clea ning cycle should be a n even m u ltiple or sub­ 9.2.1 Light Source Life. The life rating for solid state mu ltiple of the lamp replacement time interval so that sources with l ig ht emitting diodes (LEDs) is determi ned these two operations can be combined. Genera l ly, a d ifferently from that of other sources. LEDs rarely four-year cleaning cycle is the maxi m u m timeframe completely extinguish ("burn out"), as d ischarge and recom mended in relatively untai nted environ ments. filament sou rces do. Their rated l ife can be defined H owever, 9-4 in ind ustrial envi ronments, where the Maintenance and Operations l u minaires a re exposed to smoke a nd/or dust, it will be the operating status of l u m i naires in a lighting system necessary to establish a m uch shorter cleaning cycle from a remote location using a computer via the internet interva l . (see Sections 6.1 0.2 and 6.10.3). 9.2.3.2 Cleaning Methods. Depending on t h e material Photocontrols should be checked for proper orientation. to be cleaned, there are a num ber of different techniques This usually means aiming the window north u nless this ava ilable. Plastic, g lass, and sil icone lenses are used a l lows the control to "see" other light sou rces at night. in roadway l u m i naires. The manufacturer sho u l d be This may involve a site visit after dark. consu lted about the appropriate cleaning methods for these components. Photocontrol selection for LED l u m i naires is particularly important due to the potential of high inrush current. The optical assembly sho u l d be checked for i rreversible Although degradation. Over time, exposure to u ltraviolet radiation photocontrol very briefly, it is often high enough to cause from the LED and the sun will cause lenses made from excessive stress on the relay contacts (or semiconductor polycarbonate and acryl ic to d iscol or. This d iscoloration switch) in standard duty photocontrols. Heavy-d uty will reduce the light transmission to the point where (sometimes cal led long-life) photocontrols are designed they may no longer deliver the designed l ig ht level. this cu rrent only passes thro u g h the to withstand high inrush currents and may be a cost effective choice for projects with LED luminaires. Users a n d owners should be aware that roadway l u m i na i res, i n c l u d i n g those with LED l i g ht sou rces, Photocontrol life is dependent on severa l factors, will req u i re period ic clea ning to mainta i n l ight output i n c l u d i n g tem perat u re, qua ntity a n d mag n itude of l evels and l i g ht d istri butions within the m i n i m u m l i ne surges, q u a l ity and design of the control, and performance levels prescri bed i n t h i s d oc u ment. atmospheric conditions. Life may vary from 2 to 20 L u m i na ire man ufacturers should be contacted for yea rs. With a properly specified and manufactured recommended clea n i ng procedu res and frequencies photocontrol, replacement may not be needed d u ring to achieve this. Users and owners should eva l u ate the life of the l u m i na i re. the effectiveness and econom ics of these procedures d u ring their eq u i pment selection process. It i s im portant to replace fa iled photocontrols with devices having the same voltage rating and features. 9.2.4 Leveling and Alignment. Luminaires should be An actual test of voltage at the l u minaire receptacle is properly oriented and alig ned to perform as intended. req u i red if the installer is not sure. Installation and maintenance personnel should check the l u m i naires for proper positioning. One important 9.2.6 Line Voltage. Line voltage variations may affect consideration (where a pplicable) is that l u minaire optics the proper operation of l u m inaires. Proper power source should be positioned para l lel to the centerline of the a n d c i rcuit design can m i n i mize voltage reg u lation roadway. Some l u m i naires incorporate built-in level problems. Line voltage variations will damage drivers indicators; nevertheless, l u m i naires should be checked to a n d shorten l u m inaire l ife. It is i m portant to check be sure they are level. (See a lso Section 1 0.4.1.3, which voltage with the load on at the point of utilization. discusses possible exceptions to this general rule.) LED d river i nstability or damage can result if the l i ne 9.2.5 Controls. Lighting controls typica lly consist of a n voltage fa lls outside the accepta ble ra nge of operation. individual photocontrol on each l u m i na i re or a single Even a momentary dip or spike in voltage, due to photocontrol tied into a l ig hting contactor contro l l i ng routine switching by the uti lity, for example, can cause a g roup of lights. damage to the surge arrester, d river, or both. Lig hting may also be controlled via adaptive lighting Electronic d rivers for LED sou rces use power supplies control systems, which can control, monitor and record that sense the incoming voltage and su pply the correct 9-5 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities output current to the LEDs. The input voltage can to Section 3.1 .6.2.2 Voltage to Luminaire Factor for "float" over a broad ra nge of voltages (consult specific additional i nformation.) equ ipment man ufacturer for i nformation). The tolerable voltage excursion ra nge is typica l l y much g reater than the 5% d rop a l l owed for years with high i ntensity 9.2.7 Obstruction of Light and Photocontrols by Foliage. The presence of low overhanging foliage may d ischarge la mps. However, it is i m porta nt to note seriously obstruct the light delivered to the pavement as that the lower the i nput voltage, the higher the input well as impede traffic movement (see Figure 9-1). Tree cu rrent. The desig ner should eval uate the electrical trimming becomes essentia l to keep up with growth. Field i nfrastructure to determ i ne whether l a rge voltage personnel should work closely with forestry organizations excursions a re l i kely, and then consult the manufacturer and property owners to maintain illumination requirements of the prospective l uminaires to determine whether while minimizing tree appearance issues and horticultural they are suitable for the circu mstances in the field. (Refer damage (see Figure 9-2). Luminaire Figure 9-1 . Example of light obstruction caused by low tree foliage. (© I l l u m i nating Eng i neering Society) Minimum Pruning Line Figure 9-2. This recommended pruning level maintains illumination and minimizes tree damage. (© I l l u m i nating Engineeri ng Society) 9-6 Mai ntenance and Operations It is i mportant to note that even with high-mounted l u m i n a i re pole spacing, with correspond i n g ly h i g h l u m i naires, it is not necessary to prune a l l trees to the candlepower a t a n g l e s n e a r the horizontal. height of the l u m i naire, but it is imperative to prune those branches that fal l below the useful bea m. This It is a lso important to note that foliage interference may is a line from the l u minaire to the midpoint between lengthen luminaire operating time u n n ecessarily and adjacent l u m i naires (see Figures 9-2, 9-3, and 9-4). increase energy use if the foliage blocks envi ronmental Foliage midway between l u m i naires and below lamp l i g ht from reaching the l u m ina ire's photocell; the level helps to screen the view of distant sou rces; the photoce l l wi l l react as if the sun has set and turn the reduction in glare improves visibil ity and comfort for l u m i naire on. motorists and pedestrians a l i ke. This gain is particula rly i mportant on local traffic and residential roadways, Fig u re 9-4 i l l ustrates top and front views of the where l i m i ted fu nds usua l ly req u i re relatively long relationship of tree shapes and l u m i naire overhang requ i rements. These are i ntended to serve as a guide for dete rmining proper overhang distances of l u m i naires of different mounting heights and for different types of trees. Foliage i nterference affects more tha n just the i l l u m inance on the roadway pavement. The i mportance of adequate l i g hting for the sidewa l ks should not be overlooked (see Chapter 3, Figure 3-5). There can High Mount ------j -i.;;;;.;o.s-;-s;. ------ � From H>lugt Street Side Figure 9-3. Pruning guide for trees located near streetlights. For any mounting height (MH), the pruning height (PH) at distance (D) from the luminaire pole may be calculated from: PH = (4MH - D)/4. I nstructions: 1 . Stand o n observation l i n e and look toward luminaire. 2 . Remove a l l tree branches that fall below the line o f sight. (© I l l u m i nating Engineering Society) Figures 9-4. Luminaire overhang distances. 9-7 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities be instances on residential and other loca l -traffic The life expectancy of an u npainted galva nized i ron streets where good sidewa l k i l l u m ination is even more or steel pole is determi ned by the thickness of the zinc important than l i g hting of the street itself. Generally, layer coati ng. In most i nstances, the coating is corroded this can be atta ined either by a lteri ng the l u m inaire at a rate of approximately 0.1 to 0.2 mils per year, with positions or by pru n i ng, or a combination of both a m i l being 1 /1 ,000 of an i nch. This means that with a methods. typical coating of 3 m ils, the coating can be expected to last 1 5 to 30 years. 9.3 Poles and Accessories In addition to galvanizing, or as an a lternative to Poles w i l l req u i re va rying leve l s of m a i ntenance, galvanizing, poles may be painted or powder coated. A depending on their materia l . Pole base plates should be painted finish will require ongoing refinishing to both exposed and free of d irt or other foreign materials that mai ntain appearance and maintain the structural integrity may cause corrosion. Bolted connections should a lso of the pole. The finish is typically applied to the outside be inspected for corrosion and checked for tig htness, of the pole only, leaving the inside unprotected. Powder especia lly on structu res such as bridges. coating cannot be reapplied to a pole in situ. Paint applied to a galvanized pole will require careful surface preparation Al u mi n u m, fiberglass, galvanized steel, concrete, and to get the paint to stick to the zinc. However, it will tend to wood poles d o not req u i re preventive mai ntenance make the pole's finish last much longer if properly applied other than cleaning (the exception being wood) to and, with periodic refinishing to the paint, can result in an maintain appearance. Metal poles may be subject to indefinite life for the steel pole. fatigue fa i l u re and should be inspected for cracks a round the hand hole, or at the base weld. The length of time before paint refinishing is needed will depend on the color, the quality of the pai nt Reg u l a r i nspection of base mou nted poles should be product, and its application. All fi nishes will fade over conducted at specified intervals. time, regardless of the coating technology or prod uct Breakaway bases may need to be inspected more prolonged exposure to u ltraviolet radiation. Darker used. The fading of the finish w i l l be accelerated by freq uently than other pole bases, for the reasons colors typica lly fade more than lig hter colors, and d iscussed in Section 9.5.1 Preventive Maintenance. reds can fade faster than blues. Prior to refinishing poles, paint suppliers and pole man ufacturers should 9.3.1 Paint or Coating. Poles and other components be consu lted to review coating products ava ilable and made of steel or cast iron may be galvanized to protect to secure the proper preparation procedures i n order to them from corrosion. In most cases, ga lva n izing is achieve the best resu lts. applied to the pole or other component by way of During the hot­ If the finish is peeling from the pole (see Figure 9-5), dip process, the molten zinc chemica lly combines with the problem may be poor adhesion of the finish to the the steel or iron su rface to form a coating that is very pole. If possible, it is recommended that a small test the hot-dip zinc ga lvanizing process. resistant to mechanical damage. In addition, due to the area be prepped and pai nted and a l lowed to sit for electromechanical difference between the steel or iron one week to see whether the pai nt properly adheres. and the zinc, the zinc coating is consumed by oxidation If it is proved that paint adhesion is the problem, then in preference to the steel or iron, further increasing the existing fin ish should be removed from the pole, the resistance to corrosion. Typical ly, the pole or other and a new fi nish appl ied u nder controlled conditions. component is hot-di p galva nized by the supplier. It Field refi nishing should be done i n d ry conditions, may be possible to make m inor repairs to galvanized taking g reat care to protect motor vehicles and others surfaces, using a cold-galvanizing paint that can be using the roadway from paint dripping. Paint suppl iers applied by aerosol spray, or more preferably brushed on. should be consulted for proper procedures and curing Re-galvanizing of the entire pole cannot be done in situ. tem perature for field refinishing. 9-8 Maintenance and Operations Vibration dampening devices may be factory- or site­ instal led. Several types are available, including an impact dampener, Stockbridge damper, Greenfield dampener, and plastic tubes instal led inside the pole. (For more information on these types of dampeners, refer to ANSI C1 36.31 .) It is i m portant to note that using a dampening device does mitigate the stress effects of the vibration, but it is not a guara nteed solution for such an occurrence. 9.4 Maintenance of Conventional Lighting Figure 9-5. An example of a pole with a poor paint finish. Systems Conventional l ig hting systems typical ly consist of poles For a l u m i n u m poles, when the fi nish is applied, the ad hesion of the fin ish should be tested by a qual ified testing agency in accordance with ASTM International standards for paint adhesion. If paint ad hesion is sti l l problematic after removal and reapplication o f pai nt, then the a l u m i n u m pole manufactu rer should be contacted to help determine the cause of the problem. Powder-coatfinishes a re sometimesa ppl ied to a l u m in u m poles. T h e su rface preparation and application process are critical to the long-term success of the fin ish. 9.3.2 Vibration. Vibration is a special consideration (many bridges tend to bou nce due to veh icu lar traffic) that can affect the life and performance of the l u minaires. Luminaires in areas of high vi bration should be equi pped with safety cables i n case the mounting 1 8.3 meters (60 ft) or less in heig ht, with each pole having one or two l u minaires mou nted on it. Repa ir or rep lacement of the l u m inaires typical ly requ i res the use of a bucket truck. Conventional l ig ht pole assembl ies may be base mou nted or d i rect buried. Base-mou nted pole assembl ies consist of a pole, a rm or bracket for mounting the l u m i naire, a n d footing. Base mounted light poles located near the edge of the traveled portion of the roadway may be mou nted on brea kaway devices. Direct-burial light pole assembl ies consist of a pole and a n arm or bracket for m o u nting the luminaire. The bu ried portion of the pole may be supplemented with some form of encasement (e.g., concrete). Certain types of d i rect-burial poles can be designed to break away at ground l i ne. bolts vibrate loose. The l u m inaires and light sources should also be designed and tested to withsta nd the anticipated vibrations. 9.4.1 Preventive Maintenance. Each conventional l i g ht pole, including l u m i naire and arm or bracket, should be inspected after the first month of insta l lation Light poles can vi brate in d ifferent m odes and at and a proper maintenance schedule developed for the d ifferent freq u encies. It is very d ifficu lt or a l most application. At a m i nimum, i nspection should be done impossi ble to predict when poles will be affected by on a scheduled basis and any time the l u minaire is vibration, but a ny pole could be susceptible. If sufficient serviced and/or cleaned. If the pole load is changed (e.g., i n magnitude and applied over time, vibration can cause removing an H I D l u m i n a i re and i nsta l l i n g a new LED stress cracks in the pole. When a single pole exhibits l u m inaire), the inspection schedule should be fol l owed poor dampening characteristics, a vibration dampener as though this were a new insta l lation. At a m i n i m u m, may be req u i red. The vibration dampener is used to pole system inspection should include these steps: mini mize the effects of wind-induced Aeolian vibration. When this type of vibration is identified (it is site specific • • Check that the pole is plumb. Depending on pole type, look for signs of structural and unforeseeable), a dampening system is used to weakness such as cracks in the pole, discolored m itigate the stress effects. welds, decay, spa l l i ng, or fi ber "blooming." 9-9 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities • Check for deterioration and section loss in the pole mou nted on a ring. The ring assembly can typica l ly be shaft. lowered, thus a l l owing workers to service the hig h-mast Check for corrosion from dissimilar metals, if l u m i na i res without using a bucket truck. applicable. • Check for loose l u m inaire components, including mounting bolts and screws. • Check for loose l u m i naire arm attachment bolts or mounting bracket. • Check for l oose pole hardware, i n c l u d i n g n uts securing the pole base anchor bolts The raising and l owering system consists of support cables, winch assem bly, attachment hardware, and a portable or internal motor assem bly. The raising and lowering system facilitates l u minaire mai ntenance, but the ra ising and lowering system itself should a lso be maintained. • Check the i ntegrity of the breakaway device. 9.5.1 • Look for g rade changes a round the pole, including mai ntenance work on the raising and lowering system Preventive Maintena nce. Preventive soil eroded away from or deposited agai nst the should not be conducted when there a re high wind breakaway devices or pole base. A brea kaway speeds, or when there are severe weather cond itions. device may not perform as intended if its relative • elevation above the g round is too high or too It i s i mporta nt to perform preventive maintenance low. Therefore, breakaway bases may need to be on h i g h-mast lighting systems at reg u l a r i nterva ls. inspected on a more frequent basis. The l u m inaire ring assembly should be l owered and Touch the pole for vibration detection, and l isten inspected as part of this mai ntenance work. Fai l u re to for hu m m i n g noise from the pole. do so may increase the risk of eq uipment fai l u res and safety problems. If cracks a re detected i n a metal pole, a structural engi neer should be consulted for i m med iate evaluation. It is i mportant to inspect the bases of hig h-mast poles Signs of metal fatig ue wou ld normally appear as fi ne for signs of cracking or other problems. Binoc u l a rs may cracks just above the weld line, in the corners, or around be used to perform a cursory visua l inspection of the the hand hole. This is normal ly a sign of other fatigue outside of the upper portions of the pole. The pole factors. Even a small crack w i l l g row and can cause pole inspection may be sched u l ed in conj u n ction with other damage or fai l u re. preventive mai ntenance work. 9.4.2 Corrective Maintenance. Priorities for corrective There are two general types of high-mast raising and mai ntenance of l u minaires should take account the lowering systems: top latching and bottom-latching percentage of lights o ut and the relative i m pact on or n on-latching. The type of system will influence the the overa l l effectiveness of the l ighting system. For mai ntenance procedu res. example, partial lighting at i ntersections, freeway off ra mps, and other decision points is typica lly achieved Top-latching system: I n a top-latched system, the using conventional l i g hting. At these l ocations, the l u m i na i re ring latches to the head frame assem bly at fa i l u re of one l u m inaire may have a proportionally the top of the pole. Once the ring is latched, the weight g reater i mpact, and thus a hig her priority for repa ir, of the ring is borne by the latching pins and not the than the loss of a single l u m i naire on a section of support cables. continuously l i g hted roadway. Bottom-latching system: I n a non-latched or bottom­ latched system, the weight of the l u m i na i re ring 9.5 Maintenance of H ig h-Mast Lighting assembly is on the cables at all times. Systems H i gh-mast lighting systems typica l ly consist of poles Exa mples of possible problems with a l l hig h-mast of 20 meters (66 ft) or g reater height, with l u m i naires raising and lowering systems: 9-1 0 Maintenance and Operations Twisting of the su pport cables cha l le n g i n g • Power cable twisted a round the support cables mai ntenance program should be established to extend • Deterioration or damage to the su pport cables the useful l ife of the tunnel lighting system and maintain • Deterioration or damage where the support cables • connect to the l u minaire ring assembly • Winch cable too loose, or twisted on the winch drum • Deteri oration, dama ge, or l oose n i ng of the connection of the l u m i na i re to the su pport a rm a nd/ or the support arm to the l u m i naire ring assembly • Deterioration or damage to the winch assem bly a nd/or winch cable • accessibil ity options. A wel l -defi ned desig ned lighting levels. 9.6.1 Preventive Maintenance. I n order to m i n i m ize lane closures for repa i r and maintenance of l u minaires, a wel l-developed cleaning, mai ntenance and replacement sched u l e should be implemented. A good mai ntenance plan for tunnel l u m i naires will ensure that designed l ighting levels a re maintained which a l low d rivers to maintain speed and safely navigate in the tunnel. Fai lure of the motor or other electrical device Clea ning tunnel wal ls req u i res the use of chemical Exa m pl es of possible problems with top- latch ing systems: • solvents, pressu rized su per-heated water, and mechanica l cleaning devices that may have a deleterious Latching pins brea king (e.g., because the l u m inaire effect on the tunnel lighting system . Some types of ring was not level when it was latched) l u m i na i res may be prone to premature fai l u re due to • Fai lure of one or more pins to latch their inabi l ity to mainta i n water tig htness and dust • Fai lure of one or more pins to unlatch tightness-features req u i red in the tunnel environment. In selecting the eq u ipment, designers should consider Exa mples of possible problems with non-latching and its a bility to withstand washing when a high-pressu re bottom-latching systems: spray and mechanical brushes a re appl ied. This can be • Pend u l u m motion acco m pl ished by using various N EMA specifications or • Possible damage to the cables if the l u minaire ring was not ful ly engaged at the top of the pole 9.5.2 Corrective Maintenance. the I EC IP ratings1•2 (see Annex I). Materials and finishes used i n the m a n u facture of Beca use they can affect worker safety or motorist safety, problems with the ra ising and lowering system should be add ressed without delay. lu m i naires a re of specific i mportance and should be carefu lly considered when selecti ng equipment for tunnel appl ications. Dissim i l a r materials need to be positively isolated from each other. As an example, alu m i n u m and carbon or stain less steel com ponents Some high-mast lighting systems utilize a small n u m ber of high wattage lamps per pole (e.g., three 750-watt l a m ps per pole). In these systems, the fai l u re of one lamp exposed to moisture and chemicals may a llow ga lva nic reactions, which w i l l cause early deterioration of the equi pment. The same considerations a lso apply to the will result i n a proportiona l ly g reater l oss of l ig hting on materials used to l ocate and secure the l i g hting system the roadway, compared to the loss of a single lamp in to the tunnel. It is essential that chemicals in concrete be a conventional l ig hting system. Therefore, the timely isolated from some meta ls, such as a l u m i n u m and other replacement of a single fai led lamp i n a hig h-mast materials subject to corrosion. l ighting system may be more i m portant than it is with a Mai ntenance in tunnels is difficult u nder regu la r traffic conventional lighting system . cond itions or partial lane closures, as it can cause severe traffic backups and may increase the potential 9.6 Maintenance o f Tu nnel Lighting Systems for accidents. Repa i r of the l ighting system and its Tu nnel l i g hting systems have u n i q ue m a i ntenance com ponents needs to be accompl ished with m i n i m a l req u i rements time spent in t h e tunnel. due to a harsh environ ment a nd 9-1 1 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 9.6.1 .1 Mai ntena nce Factors for Tu nnels. The l u m i naire and a loss in l ig ht output on the roadway. l i g ht l evels obtai ned when the system is i nitial ized LDD m ust be considered in calcu lating the maintained will decrease due to a n u m ber of related items. The l u m i nance val ues specified for the service l ife of the recommended l u minance levels i n this Recommended lighting system . Practice represent the lowest i n-service values that should be a l l owed d u ring the operating l ife of the To a large extent, t h e val u e o f t h e LDD is dependent, i n system . It is therefore of the utmost importance inverse proportion, on the owner's investment i n qual ity that the initial l u m inance figures be higher in order of material and man ufacture of l u minaires, and on a to compensate for lamp lumen d epreciation (LLD), commitment to regular cleaning of plastic or g lassware, l umina ire d i rt depreciation (LDD), equipm ent factor lenses, lamps, and reflectors. H owever, if the l u m inaires (EF) and tunnel su rface (wal l and cei l i ng) reflectance are sufficiently sealed against the ingress of d i rt, then depreciation. These factors, which change with time cleaning of the l u m inaire lens should be enough to after i nsta l lation, may be com b i ned into a single mai ntai n the l ight output. One system cu rrently i n m u ltiplying factor for i nclusion i n calculations. This total use determines t h e I n g ress Protection (IP) rating for mai ntenance factor (TMF) is composed of the above­ l u m i naire enclosures. The I nternational Electrotechnical mentioned factors and those listed in Table 9-1 , each of Com m ission sta ndard I EC 605983 provides the test which is controlled and eva luated separately. Table 9-1 lists typical val ues used to a rrive at a TMF. A few factors are beyond the control of the l ighting system owner or operator and depend on actions of others, such as the system voltage reg u lation. It is, however, the task of the system designer to determine and apply a realistic TMF to a l l design calculations as fol l ows: methodologies to determine the degree of protection aga inst ingress of d u st, solid objects, and moisture in accordance with the classification of the l u m inaire and the I P n u m ber marked on the l u m i naire. For l u m inaires in tu nnels, the m i n i m u m class for dirt and moisture protection should conform to the I P65 rating or higher (see Annex I). The i nterva l s between cleaning may vary g reatly in order to maintain the req uired performances. Table 9-1 . Typical Values for Maintenance Factors for Tunnels Conversely, if the i ntervals of clea ning a re fixed, the use of a l u m i naire that stays cleaner in service may permit Maintenance Considerations Range of Typical Values the designer to use a lower wattage to achieve the same l ig hting results. Luminaire Lumen Mai ntenance 0.50 to 0.95 Luminaire Dirt Depreciation (LDD) 0.1 0 to 0.95 Decisions about LDD va l ue, its relation to the nu mber Eq uipment Factors (EF) 0.9 to 1 .0 and wattage of fixtu res req u i red to meet maintained Ambient Te mperature 0.20 to 0.99 service levels, and the com m itment of resources to Voltage 0.87 to 1 .1 3 regular maintenance should be considered in a life cycle Tu nnel Su rface Reflectance 0.20 to 0.90 cost analysis (see Section 5.5 Calculating Costs). Typical Total Light Loss Factor (LLF) 0.30 to 0.65 9.6.1 .3 Light Level Verification. Light level verification should be part of a tunnel lighting maintena nce plan to The various l ig ht loss factors a re d iscussed in detai l in check lighting system performance. Annex A provides Chapter 3, Section 3.1 .6. Of particu lar importance to the procedure to verify tunnel l ig ht levels within the tunnels, however, is l u minaire dirt depreciation (LDD). tunnel. 9.6.1 .2 Luminaire Dirt Depreciation (LDD). The LDD 9.6.1 .4 Structu ral Support I nspection. relates to the depreciation of l u minaire l u men output supports for tunnel l u m inaires should b e inspected on Structura l due to dirt deposits on lenses, refractors, lam ps, and a regular basis. The U.S. and Canadian governments reflectors. This a ccumulation of dirt resu lts i n a change provide g u idel ines on how often inspections should be in the photometric d istri bution emanating from the performed. 9-12 Mai ntenance and Operations 9.6.1 .5 Mai ntenance of Control Devices. It is i mportant fixture may not be possible. H i g h pressure wash i n g that the photocontrols for areas inside and outside methods t o c l e a n the tunnel su rfaces m a y i n c l u de the t u n n e l a re checked and clea ned periodically. the washing of t u n n e l l u m i na i res as wel l. In this Luminance and i l l u m inance meters should be checked case, l u m i n a i res should be tested to withsta nd this for proper aim ing, as they may shift over time. (Refer type of clea n ing before being specified. Additional to the man ufacturer's recom mendations for proper i nformation on l u m i na i re clea n i n g may be found in mai ntenance procedu res.) Sections 9.2.3.1 and 9.2.3.2. 9.6.2 Corrective Maintenance. The main purpose 9.6.2.2 Sched uling Repair Work. Good l i g hting and of cleaning the walls (and cei lings) of a tunnel is to visib i l ity play a n i m portant role in the prevention of ensure a high wa l l l u m inance as wel l as good pavement accidents in tunnels and the potential secondary effect l u m i na n ce. Tu nnel s u rfaces wi l l collect d i rt, soot, of explosion, fire, or the generation of noxious fumes. g rime, moistu re, and chemica l (e.g., salt) deposits from Repair and maintenance of l u m i naires in tunnels usually vehicle exhaust, vehicle spray, and atmospheric and req u i res lane closures, which should be m i nimized by subterra nean sou rces. This will result in depreciation of the selection of good equ ipment and a wel l-developed the original su rface reflectance uti l ized in the lighting cleaning and maintenance sched u le. Mounting location desig n . This should be taken i nto consideration in and l u m inaire construction d i rectly affect the a mount of calcu lations utilizing su rface reflectance. time that is req u i red for lane c l osures. • Luminaire replacement: Luminaire replacement is H i g h su rface refl ectance is i m portant because the necessary when l u m i naires are no longer operable su rfaces contribute to the interreflected l i g ht and or become damaged, or for LED luminaires that because i l lu m i nated su rfaces can provide a sign ificant have lost a sign ificant percentage of their l u men contri bution to vis u a l g u i d a nce for the motorist. output, typica l l y 30%. Discrete LEDs or LED arrays in As part of the design, the lighting designer should tunnel l u m i n a i res a re not typica l ly field replaced, so emphasize the cleaning cycle that was used i n the complete l u m inaire replacement may be the most design calcu lations to develop the LLF. practical a pproach for maintenance. • 9.6.2.1 Tunnel Washing. Tu nnel i nteriors benefit from Electronic component replacement: Replaci ng i noperable electronic components i n a t u n n e l routine washing to maintain designed l ig ht levels. This l i g hting system process enta i ls spraying tunnel walls and l u m i naires expense of a new tunnel l u m i naire. The i ndividual is a n attempt t o avoid the with high-pressu re water and detergent, then scrubbing replacement of d rivers, surge arresters, or other with rotati ng brushes, and finally rinsing with high­ l u m i na i re com ponents is com p l i cated pressu re water-which may have a detrimental effect vast n u m ber of l u m inaire makes, m odels, and by the on the tunnel l ighting system. Lum i na i res should be component parts. In order for the tunnel l i g hting designed to maintain water and d u st-tig htness in order system to be maintained properly, information on to withstand this proced u re. exact l u m i na i re catalog n u m bers and part nu mbers should be c l osely monitored, carefu lly recorded, and It is i m porta nt to reg u larly clea n the l u m in a i re reflector continuously updated as fieldwork is completed. and lenses due to the atmospheric p o l l utants. The This system of l u m i naire maintenance assumes that accu m u lation of d i rt, soot, and chemicals results i n l u m i na i re manufacturers will continue to support a l oss i n l i g ht output and change in t h e photometric and provide replacement parts for products in the d istribution. Period ic clea n i n g both i ntern a l l y a nd field and that these same manufacturers promote extern a l l y will va ry depending on a m bient cond itions field repairs. and l u m i na i re construction. Most l u m i na i res a re sea l ed • Driver replacement: When selecting a luminaire for to I n g ress Protection ( I P) 65 or h i g her. If so, the a tunnel, consideration should be made to the rated l u m in a i re and lens should be cleaned on the outside life of the driver within the luminaire. If the rated only. Re-esta blishing the I P rati ng after opening the life of the luminaire driver is less than the expected 9-13 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities l ife of the luminaire, maintenance will need to be • performed over the life of the luminaire, or premature replacement of the luminaire may be required. Location: Street address, pole n u m ber, or relative location (e.g., near the pizza parl or). • Type of ma lfunction H I D luminaire relamping: Information about a chosen 9.7.3 Trou bleshooting H I D tunnel l u m i naire and the mortal ity of its va rious troubleshooti ng section is intended to help the qual ified LED Lu m i naires. This electronic components should be researched from the service person quickly diagnose a n LED l u m inaire issue. manufacturer's tables and graphs. From these facts, a Commonly encou ntered problems with LED l u m i naires practical g roup relamping sched u le can be esta blished. incl ude: Record keeping of the performa nce of luminaires and their com ponents is recommended. I nformation on • Luminaire is operating d uring daytime • Luminaire is not burning g roup relamping and spot relamping of H I D l u m i naires • may be found in Section 9.13.3. LEDs a re flickering or strobing, or only a portion of the LEDs a re burning • su rrou nding l u m i naires 9.7 Trou bleshooting, Repair, and Replacement Performing corrective work is the most expensive part of Luminaire is noticeab ly d i m mer or brighter than • Other damage a roadway l ighting maintenance prog ram. It is im portant that accu rate l ocation and fault type information be The approach to solving the first problem is l i kely a secured before dispatching service personnel. photocontrol issue and should be handled sim ilarly to the method used for photocontrols on H PS l u m i naires Because there are many factors that can affect roadway lighting, this section outlines a basic field maintenance procedure, which may be adjusted to fit individual systems. (see Section 9.7.4), including: • • Instal l a shorting cap Determine whether proper voltage is present at the fixture When replacing l i g hting system com ponents, care should be taken not to compromise original photometric, electrical, or structural performance. Replacement components should meet the original design i ntent as wel l as comply with cu rrent codes and standards. 9.7.1 Procedures for Night Patrol Service. • Check the cu rrent draw of the l u m inaire to verify that it is reasonable for the measu red voltage. Note: Diag nostic e q u ipment that plugs i nto the p h otocontrol When night patrol operations are used, it is u p to each service provider to determine the extent of repa irs to be u ndertaken at night. Often, the night patrol is used to identify non-fu nctioning l u minaires, which are then logged for day shifts to repai r. Alternatively, a night shift may be used to repair l u m i naires as they a re found. receptacl e is ava i l a b l e to assist i n troubleshooti ng l u m inaires. The approach for solving the other problems incl udes these steps: 1 . Ensure that power is available at the l u m i naire. 2. If power is ava ilable and the LED w i l l not start: Determine whether proper voltage is present. 3. Open the pole hand hole (if applicable), and check 9.7.2 Information Gathering. Knowing the location for damage to the surge arrester, fuse holder, fuses, of a fai l ed or damaged l u minaire and the nature of and splices, and replace as needed. (Important: the malfu nction will greatly reduce the work time and Some of these steps will req uire the circuit to repair cost. Exact l ocation i nformation will m i n i m ize be de-energized with the proper l ock-out/tag-out needless site investigations and repeat complaints procedu res in place.) about u n resolved problems. Uti l izing a mapping or 4. If the field technician is a uthorized to open the routing system w i l l efficiently m i n i m ize travel between l u m i na i re and i n itiate fiel d repairs, follow the repair sites. The minimum information needed is: l u m i na i re 9-14 m a n ufa c t u rer's recom m e n d a t i o n s Maintenance and Operations for mai ntena nce. This may i n c l u d e l u m i n a i re replacement or d river replacement. The approach to handling each of these problems incl udes these considerations and the steps that fol low: 5. If the d river can be replaced: Visua lly i nspect the • LED driver, surge arrester, photocontrol receptacle, Lamp on conti nuously (day-bu rner): 0 Make sure photocontrol is not shadowed by and internal wiring. A common fa i l u re for LED foliage. l u m i na i res is the LED driver, surge arrester, or both. If this is not the case, then . . . Replace the surge arrester or LED driver with a 0 known good mod u l e that is compatible with the ANSI type and voltage rating. Leave it u ncovered. LED l u m i naire per the l u m i na i re manufacturer's If the lamp continues to burn, then . . . reco m mendations. It is im porta nt to provide a ° compatible driver that meets the original l u m inaire Electrical characteristics such as d rive cu rrent, voltage, and d i mming protocol • Check for a loose or broken neutral from l u m inaire su pply to photocontrol socket. performa nce specifications, including: • Replace photocontrol with a new one of correct • Lamp cycles on and off: 0 Replace lamp with new lamp of correct ANSI type Thermal characteristics, including m i n i m u m and and wattage rating. maxi m u m ambient tem peratures If the lamp continues to cycle, then . . . Operating frequency, power factor, a n d total 0 Ensure that photocontrol is not aimed at another harmonic distortion l u m i naire or other bright l ig ht sou rce. • Mounting, size, form factor, and wiring method If the photocontrol is aimed properly, then . . . • Over-temperatu re protection that turns light ° Check for loose connections, including "seati ng" source off u ntil normal operating temperature is the lamp in the socket. achieved If the lamp continues to cycle, then . . . • The reg u latory l isting (e.g., U L, CSA, cUL) • Loose connections and proper wiring ° Check for l i ne voltage fluctuations: • 6. If the preced ing actions fa i l to solve the problem, High a m bient l i g ht l evels or a photocontrol aimed at a high-level l ig ht source can cause replace the l u minaire, being mindful of the original lamp cycling. In some cases, if the l u m i naire design intent, including l u men output, correlated is aimed at a high-reflectance su rface such color temperature (CCT), and optical distribution. as a l i g ht-colored wal l, the photocontrol can 7. Refer to the original l u m i naire warranty for l u m inaire trigger and cause the lamp to cycle. To avoid replacement if appl icable. this problem, it is recom mended that a n ig ht inspection be made and that the photocontrol 9.7.4 Trou bleshooting H PS Luminaires. This be aimed away from other light sources a nd/or trou bleshooting guide is i ntended to help the service l ig ht colored su rfaces. In severe cases, a shield person qu ickly d iagnose a high pressure sodium (H PS) may need to be insta lled on the photocontrol. l u m i na i re and ensure that the problem is fixed on the first attempt. • H i g h-vibration i n stal lations, such as those found on bridges or ta l l poles, can cause a lamp to cycle. The best solution for this type There are four com monly encou ntered problems with H PS lighting systems: of cycling is to identify the vibration source and then apply a vibration dampener to the • Lamp on continuously • Lamp cycles on and off proble m . It should be corrected as soon as • Lamp will not start possible to avoid lamp, l u m i naire, and even • Lamp bu rns d i m ly pole damage. pole. Cycl ing is the first symptom of a vibration 9-15 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities • La m p wil l not start: 0 lamp insta l l ed in a lower-wattage l u m i naire (e.g., Replace lamp with known good lamp of the a 1 50-watt lamp installed i n a 1 00-watt l u minaire) proper ANSI type and wattage rating. will cause a d i m lamp cond ition. 0 If lamp does not start, then . . . 0 0 Ensure that power i s ava ilable at the l u m inaire's Other possibi l ities: • A leaking seal between the base and the g lass terminal block. envelope may cause a l a m p to burn d i mly; If power is available and the lamp will not start, then . . . replace the lamp. Visually i n spect the b a l l a st, ca pacitor, • La m ps that burn d i m l y may i ndicate h i g h ­ resistance fau lts t o g round on underground photocontrol receptacle, and i nternal wiring for systems, especia l ly on the neutra l conductor. If bu rned windings or wiring and l oose wires. this is the case, the fa u lt should be found and If the ballast, capacitor, receptacle, and wiring repaired, or the cable replaced. appear undamaged, then . . . 0 Insta l l and cover a known good photocontrol or i nsta l l a shorting cap. Check that line voltage is 9.8 Maintenance Management System present on the red l ead from the photocontrol Guidelines receptacle. A m a i ntena nce management system provides the If the lamp will not start, then . . . 0 Insta l l a similar-wattage mercury lamp (for 200- information and control needed for efficient operation and maintenance of a roadway lighting system. The watt throug h 400-watt l u m i naires, a 2SO-volt need for any or all of the functions or records l isted in fi lament lamp may be used). If this test lamp this section wil l depend on the maintenance system's starts, it is a good indication that the bal last and size and type. Presented in this section is an example of associated wiring are fu nctioning properly but o n e utility's roadway l i g hting department structure and the ig niter is fa u lty; replace the igniter with one its o perating procedures. known to be good and reinsta l l the H PS lamp. 0 If the preced ing actions fa il to solve the problem, replace the l u minaire. • Lamp bu rns d i m ly: ° Check for low supply line voltage; this wi l l nearly a lways be caused by a high resistance connection on either the line or the neutral coming i nto the l u m i naire. If the line voltage is proper and the lamp is still dim, then . . . 0 0 9-1 6 9.8.1 I nspections, Patrols, and Public Reporting. It is recom mended that routine patrols be undertaken by the agency that owns the lighting system to ensure that all l ig hting and electrical systems are operati ng. Patrols should be undertaken in a structured manner to ensure that a l l l u m i naires a re inspected on a reg u l a r basis. Patrols should typica lly be undertaken d u ring hours of da rkness to confirm that the lighting is operationa l . Occasional daytime patrols might identify inoperable o r damaged photocel ls. Ensure that the l u mi n a i re voltage rating and the line voltage match. This can be done by To ensure that the work by the maintenance contractor reading the voltage rating of the l u m i naire on the or a gency crews is being undertaken in a satisfactory man ufacturer's label inside the l u m inaire. manner, routine inspections should also be undertaken. If the luminaire is properly rated for the supply voltage, then . . . Inspections and patrols should be documented and maintai ned for future reference. Ensure that the correct wattag e lamp i s instal led. Again, this information can be obta ined from the Public reports of damaged or ma lfunctioning equ ipment man ufacturer's label found inside the l u m i naire. can a lso be i nva lua ble to owners for identifyi ng The ANSI lamp type and wattage rating a re mai ntenance needs. It is recom mended that owners sta mped on the lamp envelope. A higher-wattage develop a program for routing publ ic reports, including Maintenance and Operations those provided by pol ice agencies a n d roadway Identification of poles and luminaires by nu mber contractors. Owners may advertise telephone nu mbers a nd/or add ress, plus the geog raphical location (G IS for ca l l i ng in such reports, both to the public and other coordinates) l ocal agencies. • Luminaire size and type; lamp wattage, type, and socket position, if applicable (if possible, include 9.8.2 Requirements. manufactu rer's cata log n u m ber) • 9.8.2.1 Fu nction Requirements. Personnel should be considered along with materials, equ ipment, and other photocontrol, as a pplicable factors that may affect m a i ntena nce management. • Certain functions that should be included a re: Manufactu rer's name for each lamp (ANSI code and wattage), l u minaire, bal last model and type, and Type of construction (overhead or u nderground wiri ng) • Program direction • Operations supervision • Record keeping diameter, and mast arm (or bracket) length • I nventory control Original i nstallation date and the replacement dates • Service a nd/or troubleshooting of a ny component parts • heig ht, manufactu rer, cata log n u m ber, bolt circle • Additional i nformation may be fou n d i n Annex J, Section J.1 . 9.8.2.2 Record Keeping Requirements. Records make it and forecast budgets. Computerized asset ma nagement systems are available that can accomplish the required tasks. Col lection of the fol lowing data is recom mended, with a l l records computerized for easy access: • Lig hting system inventory (initiate and keep current) • Pole or l u m i na i re n u m bering or identification (properly locate all l u m inaires) • Map sets (locations shown for a l l l u mina ires) • Operation file (sched ule all maintenance) Record of ma lfu ncti o n i n g • G roup a nd/or spot relamping dates • Photometric data if appl icable (single-l u m inaire iso­ i l l u m inance plots or candela val ues) l u m i n a i res for incoming and outgoing materials, equi pment warranty status, a n d a ny defective materials • include or provide for: • A l ist of approved manufactu rers • Material specifications • Method for receiving new material (note forces system necessary for mainta i n i ng roadway l i g hting system operation. A system for handling these items should Method for defective material retu rns (made under warranty) Record of operational fieldwork completed by field Tracking 9.8.2.3 Material Requirements. Proper materials are • components replaced when making repairs) • Maintenance records with outage i nformation, dates, and reasons possible to schedule work efficiently, identify problems, • Type of poles (wood, a l u minum, steel), mounting Records documenting the proper d isposal of • Incoming material inspections • Lighting system waste d isposal 9.8.2.4 Equipment Requirements. All service vehicles should be eq u ipped with sufficient tools, traffic safety devices, and cleaning equ ipment. Each veh icle should carry materials, ladders, l ift platforms, a n d bu ckets a ppropriate for the l u m inaire mounting heig hts. l ighting system waste 9.8.2.5 Operations. Annex J provides a n exam ple Certain details a re needed with in the records to control of a deta iled m a i ntenance plan. Such a plan can a n d monitor the l i g hting system. This i nformation always be mod ified to serve individ u a l needs a nd/or should include: organizational structures. 9-17 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 9.8.3 Operations and Asset Management via Networked Systems. Computerized systems for manag­ An example of a working l u m i na i re monitori ng and control system is shown i n Figure 9-6. ing lighting assets should be considered. Systems (includ­ ing retrofit devices) are available that monitor critical A networked asset management system can have functions of the luminaire, and even detect outages. The significant im pacts on the operation of lighting systems, information can be accessible from a personal computer including: in the operations office of a streetlight plant. Systems available feature complete mapping tools, whereby infor­ • Preventive mai ntenance a nalysis • Inventory a nalysis • Work management ana lysis • Asset management mation on problem streetlights is sent across the internet and represented on a geographical information system (GIS)-accurate map. Software can then plot the most effec­ 0 Electrical system maintenance maintenance action to take place at each luminaire. This 0 Asset tracking type of system is more fully discussed in Annex B. 0 Electrical safety eq u ipment tive route for maintenance crews, providing the specific Com mun ication to Control/Monitor Facility at Termi nus of Wi reless Network Streetlighting Wi reless Network Wireless Communication Between Luminaires � / ,,.,. Each Luminaire Identified by GPS Coordinate ... ... Control Functions Allow Real Time Switchi ng, and Dimming of Individual Luminaires Control/ Monitoring Facility Maintenance Crews Dispatched as Needed on Optim ized Route Asset Management Report Detailinq Mai ntenance Needs Figure 9-6. Luminaire monitoring, control, and asset management system. (Map g raphic courtesy of Streetlight I nte llige nce) 9-18 Monitoring Fu nction Allows Real Time Monitoring of Each Luminaire's Performance Mai ntenance and Operations • end of l ife. If cycling l a m ps a re not replaced promptly, Power metering and monitoring 0 Tariffs ° Flat rate billing 0 Metered service 0 Meter accuracy ignitor a nd/or ballast fai l u re can res u lt. (Non-cycling H PS systems are available.) Thus, it is i mportant to replace H I D lamps before the end of rated life so that the designed-for i ll u m i nation levels are mai ntained and the n u m ber of outages is red uced. These topics are covered in detail in Chapter 6, Section Factors that affect the life of all commercial H I D lamps 6.1 0.3 Adaptive Lighting Operations. incl ude: • I nstallation (i .e., mechan ical m o u nting of the eq uipment) 9.9 Light Source Failure • Vibration control • Luminaire design and operating characteristics • Lamp operating wattag e • L a m p a mbient temperatures • Bal last characteristics tends to be rooted in g radual degradation rather than • Line voltage catastrophic change. The performa nce of LEDs can be • B u rning hours per start 9.9.1 Light Emitting Diode (LED) Failure. LED l i g hting is incredibly robust and rel iable; however, LEDs have two pri mary classes of fai lure: g radual and "catastrophic," i.e., sudden and complete). With rare exceptions, LED fai l u re reduced and even fail due to therma l degradation, the quality of materials, structural defects, pole vibrations. 9.9.2.1 Metal H alide (MH) Lamp Failure. With meta l The qual ity of the material in a n LED has a direct i m pact used to control current flow through a la mp. Light is on its performance and l ifetime. The larger the n u m ber produced when a n electric cu rrent flows through a of defects in the material, the greater the likelihood mixture of gases and vaporized metals. halide sou rces, a cu rrent-li miting device (ballast) is that electron-hole recombi nation w i l l g ive rise to non­ radiative decay. Normal end of l ife is due to deterioration of the electrodes. This may cause the arc tube ends to blacken Structural defects i ntroduce a different kind of l oss by and the l ig ht output to fa l l off dramatically. Eventual ly, creating paths for leakage current, opening the way for such an i m paired lamp w i l l no longer start. reverse-bias cu rrent flow. If there is a m ismatch between the ballast and the In tests of u ltraviolet LEDs, electrical stress degraded l a m p, damage to the arc tube will result and the lamp performa nce more than thermal stress. Open circuits will fai l . Gases or metals lost from the arc tube through can be a problem, particula rly for LEDs wired in series m i g ration to the outer b u l b, or air leaking i nto the outer with other components. If one device goes open circuit, b u l b, will also cause lamp fai lure. it can take the whole string with it. In some cases, near the end of life, the a rc tube of Add itional i nformation is provided in Section 6.3.1 . a metal halide lamp may ruptu re, causing the outer envelope to fracture. (See also N EMA Standard LSD 9.9.2 High Intensity Discharge Lamp Failure. For 25-2008, Best Practices for Metal Halide Lighting Systems.4) high intensity d ischarge ( H I D) lamps (high pressure sod i u m, H PS; low pressure sod i u m, LPS; metal hal ide, 9.9. 2.2 High Pressure Sodium (H PS) Lamp Failure. M H), it is i m portant to u nderstand not only rated l ife Although (refer to Section 6.3.2) but a lso the manner i n which are similar in appearance to meta l halide arc tubes, such lamps perform over their l ives. For example, H PS the primary fai lure mode of H PS lamps is different. l a m ps can be expected to cycle on and off as a signal of H i g h pressure sod i u m l a m ps should be used with high pressure s o d i u m (H PS) a rc tu bes 9-1 9 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities the a ppropriate H PS bal last designed for the rated of a l u m i naire by 50 percent or more. Replacing lamps l a m p wattage and voltage. Gases, including vaporized before the end of their rated lamp life and cleaning metals, can leak from the a rc tu be, or air can leak into the l u m i na i res both sever to red uce l i g ht output the outer envelope, resulting in fai l u re. Normally, as an depreciation. The "best time schedu le" is when the H PS lamp ages, the voltage req u i red to keep the lamp total cost of insta l lation, energy use, and relamping is operating increases to a point where the ba l last voltage at its m i n i m u m . For many i nstal lations, a gro u p rela mp can no longer sustai n the cu rrent flow, causing the lamp conducted at two thirds to three-fourths of the rated to exti nguish. Once the lamp has cooled sufficiently, it lamp l ife provides the m ix of m i n i m u m acceptable l ig ht will reignite, causing a n on-and-off cycling condition. levels and l i m ited outages, yielding the lowest cost. This cycling is typical for a n H PS lamp near the end of (See Section 9.13.3 for a deta iled economic analysis of its life. Eventual ly, the lamp will no longer start. Lam ps spot relamping versus g roup relam ping). Regardless of should be replaced prom ptly to avoid damaging other which sched u le is chosen, a l l spent l ig hting components com ponents. sho u ld be recycled or d isposed of in accordance with environmenta l reg u lations. 9.9.3 Low Pressure Sodium (LPS) Lamp Failure. The most common cause of fai lure for low pressure sod i u m The opti m u m relamping period can be determined (LPS) lamps is deterioration o f t h e electrodes in t h e a rc from the man ufactu rer's lamp su rviva l and l u men tu be. These lamps do not exhibit the on-and-off cycle m a i ntena nce cu rves. Alternatively, m a i nten a n ce typical of old H PS lamps, b ut they eventu a l l y reach a personnel can monitor i l l u m ination levels and relam p point where they w i l l not start. a t o r near the m i n i m u m accepta ble value. I n either case, l u m i naire cleaning should be schedu led to coincide 9.9.4 I ncandescent Lamp Failure. The cause of with the relamping to m i n i m ize labor costs. inca ndescent lamp fai lure is a broken filament. This may be due to shock, vi bration, excessive voltage As light levels appl ied to designs a re based on end (higher than the lamp design voltage), or normal end­ of l a m p life, when developing a relamping policy it is of-life burnout. Air leaking into a bulb cracked by rough critical to consider the l ig ht loss factor appl ied to the handling or water damage can a lso cause such fai l u re. lighting desig n . For example, if the l i g ht loss factor is 9.9.5 Basic Relamping Practices and Choices. Due than if the light loss factor is low (0.5 to 0.8). Some light to the cost of labor, replacement of the light sou rce, sou rces, such as probe start meta l hal ide, may req u i re typical ly cal led re/amping, is a particu larly expensive rela mping every year, whereas other l i g ht sources part of l ig hting system maintenance. There are two may req u i re rela mping every 4 years. Maintena nce relamping practices: spot re/amping and group re/amping. of l i g ht levels is the primary factor in determ ining h i g h (above 0.8) then one may relamp less frequently g roup relamping policy for LED l i g hting systems. The Spot rel a m ping is the proced u re of replacing a lamp j u risd iction mainta i n i ng the l ighting system should when it has failed. The response ti mes to replace a fai led define rel a m ping policy and advise those u ndertaking or cycling lamp should be estab l ished. Some owners design to apply the proper factor to ensure l ig ht levels patrol a l ig hting system on a sched u led basis, replacing can be maintained thro u g h the end of lamp life. lamps as necessa ry. Many cities and utilities depend on pol ice reports and citizen ca l l -ins to locate outages. It is i mportant to recognize that some lamp fai lures Street l ighting monitoring systems (see Sections 6.1 0.2 will occur before the average rated l ife of the lamps is through 6.1 0.4 on adaptive lighting systems) will a lert reached. Traffic safety concerns a l one dictate that fai led asset owners of light outages as wel l . l a m ps should be replaced as the outages occur. G roup rel a m p i ng is t h e procedure where a l l l a m ps The spot relamping or g roup relamping decision is a a re periodically replaced on a "best time schedule." matter of user choice, based on design and economic Over time, LDD and LLD can reduce the l ig ht output considerations. A g roup relam ped i nstal lation has more 9-20 Maintenance and Operations evenly aged la mps, while a spot relamped system wil l considered: namely, pedestrian pathways where the have lamps o f a l l ages, including some with severely l u m i na i res are not intended to i l l u minate roadways. The reduced l ig ht output. Modified spot relamping, where designer should be carefu l to choose the appropriate l a m ps a re replaced if they reach a "target l ife" based LED lamp that is compatible with the l u minaire housing on lumen mai ntenance considerations, can l i m it l u men in the pedestrian-scale l u minaire and provides sufficient depreciation to a n acceptable level. i l l u m ination accord i ng to the design criteria. A mockup may be helpfu l prior to fu ll deployment to help predict It may cost less (on a per-lamp basis) to g roup relamp i l l u m ina nce performa nce. The fol lowi ng a pproach and clean than to spot relamp and clea n . This is offset by on-site approach should be considered: the fact that proportionately more lamps are replaced 1 . Ensure that power is off to the l u m i na i re a n d and cleaned in a grou p-relam ped system than in a spot t h e mockup is performed b y q u a l ified service rela mped system. But regardless of program choice, personnel. wel l - p l a n ned sched u l es a re needed for p u rchasing 2. Remove the existing HID lamp and replace with the l a m ps and then a l locating personnel and eq u i pment i n proposed LED lamp. Consider repeating for several t h e most economical man ner. luminaires in a row. LED mod u les and other components may or may not be replaceable, as determined by the manufacturer's recommendations. Light source replacement may entail removing the fixture and re-soldering "modules." LEDs are becoming less expensive and more efficacious every year. When the appropriate time comes to "rela m p" LED fixtures, it may be beneficial to weigh the cost of a new l u m i naire against the cost of the LED module and the labor req u i red to i nsta l l it. 3. Verify that the weight of the LED lamp does not put u ndue stress on the HID socket. 4. Perform Except in the case of a lamp fa ilure, the repair of a failed • Replace the entire l u m inaire on site. • Bring the failed l u m i naire to an off-roadway facility i l l u m i n a n ce survey, record i n g measurements with c a l i b rated a i l l u m inance meter. One a pproach is to tempora ri ly bl ock light output from adjacent l u m inaires and measure the i l l u m i na nce created by only one proposed LED lamp. Measu re the i l l u m inance at reg ular intervals. 5. Use roadway lumi naire typically involves one of the fol lowing: an i l l u m i na nce this i i l u m i na nce i nformation to pred ict i l l u minance across the site. 6. Repeat the approach with various LED l a m ps if needed. for exa mi nation and repair or d isposal. 9.1 1 Disposal of Components At a g iven l ocation, the labor, equ ipment, and traffic H i g h i ntensity d ischarge ( H I D; high pressure sod i u m control costs to replace one l um i naire wou ld typica lly a n d meta l halide) lamps and l o w pressu re sodium lamps be similar for H I D and LED l u m i naires. may be classed as hazardous waste and, as such, shall not be simply discarded as refuse. 9.1 0 Relamping With LED Retrofit lamps Hazardous waste lamps a re added to the federal l ist While some LED l a m p manufacturers prod uce LED of u niversal wastes reg u lated u nder the U.S. Resource l a m ps that a re compati ble with H I D sockets, this Conservation and Recovery Act (RCRA). Regu lati ng appl ication is problematic for lig hting i ntended to these lamps as a u niversal waste u nder 40 CFR Part 273 i l l u mi nate the roadway. It is diffi c u lt to predict how provides for better management of them and facilitates the LED lamp and l u mi n a i re reflector w i l l optica l ly complia nce with RCRA hazardous waste req u i rements. perform. The size, weight and shape of lamp should Under Subtitle C of the RCRA, hazardous waste should be eval uated for that particular i nsta l lation and bal last be properly identified, stored, transported, treated, compati bility (if appl icable). However, there are some a n d d isposed of. In addition, a n u m ber of states have outdoor appl ications where this method may be ban ned the d isposal of mercu ry-conta ining lamps. 9-21 ANSl/IES RP-8-21, Recommended Practice: Lighting Roadway and Parking Facilities When H I D and LPS lamps a re taken out of service, the 9.1 3 Economics manufacturer's data may be used to help determine One way to select the best roadway l i g hting system whether they are a hazardous waste. Local and state for a specific appl ication is to compare the cost of regu latory bodies should be consulted. Lamps with various systems on a l ife cyc l e basis. The l ife cyc l e hazardous materials may be d isposed at waste depots c o s t a n a lysis i n c l udes consideration of costs s u c h approved to d ispose of such mate ria l . Additional as ca pita l costs, cost o f money, projected e n e rgy information on the disposal of hazardous-waste lamps costs, a n d m a i ntenance costs. This section w i l l address can be found onli ne.5 only m a i ntena nce costs. (See Section S.5 Calculating Costs for complete descriptions of capital, operati ng, The a rc tube of a low pressure sodium lamp contains a and life cycle costs.) somewhat g reater a mount of sodium than that of a high pressure sod i u m lamp. Because sodium w i l l generate The heat when exposed to water, it is recommended that the mai ntenance is keeping operational costs low while sodium i n the arc tube be neutralized before d isposing preserving the original l i g hting design concepts. pri m a ry be nefit of proper l i g hting system of the lamps. One method is to careful ly break up used lamps i n quantities of 20 or less, placing them in 9.1 3.1 Light Loss Factors. a clean, d ry container in a n open area. Once the outer c a l c u lations i ncorporate l ig ht l oss factors. Those t h a t la mps and arc tu bes are broken, a hose is used to run a re recovera b l e water into the container u ntil the g lass and other lamp factors (see Section 3 .1 .6.1 ) a n d become very The l i g h t i n g d e s i g n a re someti mes c a l l ed maintenance parts are completely covered. The water is a l lowed to i m p orta nt over the l ife of a l i g h t i n g i nsta llati o n . If stand for a few m i nutes; some bubbling may occur as t h ey a re not contro l l ed, t h e ori g i n a l design concept a result of the interaction between the sodi u m and the and the i n it i a l i nvestm ent m ay be lost or seriously water. After a short period of exposure to water, the deg raded. C a refu l m o n itoring, coupled with pro m pt sodium will be completely neutralized. Disposal of low rem e d i a l action whenever component fai l u res occ u r, pressure sodium la mps or lamp parts should be done in can res u l t in s i g n ifica nt savi ngs in tota l operating accordance with applicable local, state, provincial, and cost. federal reg u lations. 9.1 3.2 Record Keeping. Records on the life history Many light emitti ng d iodes (LEDs) are Restriction of of each l um i n aire in the system are i mportant to Hazardous Substances (RoHS) compliant6; however, the maintenance program. These data help identify there may be other components in the LED l u m inaire problems before they arise, enabling the system to that should be treated as hazardous waste. (Consult the perform at or near its design goal while operating costs manufacturer's material-safety data sheets (MSDS) and are kept to a m i n i m u m . local environmenta l authorities.) 9.1 3.3 Group Versus Spot Relamping. Table 9-2 shows a sample mai ntenance cost comparison, using nominal 9.1 2 New Light Sources and Components costs, for both group-relamped and spot rela mped Emerging technologies i nclude "smart" l ig hting control systems. The driving factors in this comparison are the systems. relative labor costs for g roup relamping versus spot For any new tech nological advance, it is i mportant becau se only one lamp is replaced per spot location, rela mping. Travel time i ncreases for spot relamping to ensure that the product i s certified safe by a s i g n ificantly i ncreasing qualified organization such as U L, LLC, or Canada's CSA Table 9-2, this expense more than compensates for labor costs. Accord i n g to G roup before i nsta l lation in the public domain, and the increase in material (lamp) costs associated with performa nce modeled to ensure lighting criteria are g ro u p relamping, and makes g roup relamping the less met for the roadway. expensive a lternative. 9-22 Maintenance and Operations Table 9-2. Economic Analysis Comparing Group Relamped and Spot Relamped Lighting Systems (Total Annual Maintenance Costs, U.S. Dollars) Line # Item Description 1 Total number of l u m i naires in system 2 Ave rage l a m p costs Group Spot Relamp Relamp 50,000 50,000 $10 $10 3 N u m be r of l u m i naires cleaned and g roup re lampe d per year 1 2,500 -0- 4 Cost of la bor, truck, and components for spot rela mping $100 $ 1 00 5 Cost of la bor, truck, and components for g roup rel a mping $1 1 -0- 6 Annual spot relamping or clean i ng rate: weighted average failure 0.060 0.145 7 Estim ated n u mber of spot replacements per year (#1 x #6) 3,000 7,250 8 Annual cost of spot replacements [(#2 + #4) x #7] $330,000 $797,500 9 Annual cost of g roup replacements and cleaning [(#2 + #5) x #3] $262,500 -0- Total Cost (#8 + #9 ) $592,500 $797,500 rate. (Data taken from lamp man ufacturers' mortality cu rves.) Table notes: • This ta ble is only an illustration of the d ifferences i n cost between spot rela m ped and g roup relamped systems, and the factors i n this ta ble are examples. Actual values should be determined by the user for each specific lighting system, and should be modified to serve individual situations and service provider needs. • Even with a g roup relampi ng program, there will always be some spot fai l u res that need to be dealt with as they occur. • This exa m p le is based on a four-year re lamping cycle and on lamp failures only. Lamp failure data do not include cost recovery of prematurely fa iled lamps. Actual costs and the relative merit of spot relamping 9.1 4 Methods of Contracting versus g roup relamping will depend on the physical Mai ntenance may be u nderta ken by the owner's extent of the lighting system and on the fraction of early in-house maintenance staff or via a third party agreement fa ilures that occur d uring the chosen g roup relamping (contract) with a contractor. The more traditiona l period . method is either directed on an "as and when needed" basis; alternatively, it may be u ndertaken on a reg ular 9.1 3.4 Maintenance Budgets. M a i ntenance cost sched u l e based on specifications. With a specifications­ analysis should be underta ken to develop a total annual based a pproach, the owner or its agent identifies the mai ntenance budget for a roadway l ighting system. The means and methods to accomplish the mai ntenance as largest costs are those incu rred for the replacement of wel l as the interval between maintenance activities. This l u m i naires. Maintenance practices should be consistent is called method-based maintenance. with, or improve upon, the original system desi g n . A new a pproach is performance-based maintenance. 9.13.5 Energy Costs. In general, for H I D lamps the This approach (a lso referred to as outcome-based energy consumption of a system is the same with new maintenance) d iffers s i g n ificantly from m ethod­ lamps and clean lum inaires as it is with old lamps and based maintenance i n that q u a ntifiable performance dirty luminaires. For a g roup relamped system, the longer outcomes are specified, rather than work in puts. The the period between relamping a nd cleaning, the lower important factor is that the specified outcome is met, the overall average l u men output of the luminaires. not the amount of work or services provided. The effectiveness of the maintenance activity is monitored Timely repa ir of lamps that stay on continuously ("day by comparing defined objective performance measu res bu rners") is important in order to keep light output and to actual conditions. The benefit to this approach is that lamp life within the original planned allowances. it can fix costs. In order to undertake a performance- 9-23 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities based contract, the condition of the assets w i l l need to be clearly identified as part of the contract. An example of performance-based mai ntenance is where the outcome is to have 90 percent of the street l i g hting in a n a rea operating at all times. The asset condition itself may be specified as a n outcome, to ensure that the l i g hting assets do not degrade to the point where safety is compromised. The terms and conditions do not define how the mai ntenance is done, just the expected outcome. The measure would define a m ethod of checking to verify that the outcome is being met. 9.1 5 Equipment Testing The testing of roadway lighting eq u i pment is very im portant. Tests should occur before the owner ag rees to pu rchase and insta l l a ny new com ponents in a l ig hting system . After initial (or q ua l ification) tests, each order d e livered should be spot-checked to confirm that the equ ipment meets specifications. The actual atta ined l ight level may be greatly affected by a ny change in equ ipment q u a lity. Most often overlooked is the testing of l i g hting eq uipment removed from the field. I n fact, such testing will pay for itself and may even offset m uch of the onsite labor cost for mai ntenance. It w i l l also return equi pment to service, provide mortal ity i nformation, and esta blish records that g ive a n in-depth look at conditions system-wide. Even when equ ipment is found u nusable or subject to premature fai l u re, testing w i l l help determine t h e reasons. T h e extent o f t h e testing will vary depending on the l ig hting system objectives. Test records w i l l be a mong the most important tools affecting future i nstal lations, mai ntenance procedures, budget planning, and other matters associated with the l i g hting system. It is also important that lighting designers know a bout m a i ntena nce problems. This information will assist them with future projects. 9-24 Maintenance and Operations A D D I T I O N A L R E AD I N G Note: This section is not part o fANSI/JES RP-8-27. It is included for informational purposes only. National Electrica l Manufactu rer's Association. Standa rds for Roadway and Area Lighting Equi pment. Arli ngton, Virg.: N EMA. (ANSI C 1 36 Series). Clark F. Accurate maintenance factors. I l l u m i nating Engi neering. Mar 1 963;58(3):1 24. Federa l H i g hway Ad ministration. Hig hway and Rail Tra nsit Tu nnel Mai ntenance and Reha bilitation Manual. Washington, DC: FHWA; Mar 2003. International Commission on I l l um i nation. CIE 33A/B-1 977, Depreciation of I nsta l lations and their Maintenance (in Road Lig hting). Vienna: CIE; 1 977. Lutkevich P, Mclean D. International Mu nicipal Signal Association Roadway Lighting Level II Certification Course; 2007. Mclean D, Lutkevich P, Lewin I. Guide for the Design of Roadway Lig hti ng. Ottawa: Tra nsportation Association of Canada; 2006. Federal H i g hway Ad ministration. Roadway Lighting Handbook. Washington, DC: FHWA; Dec 1 978. (FHWA Package 78-1 5). Van Dusen HA Jr. Mai ntenance and adjustment factors in street l i g hting desi g n calcu lations. J I l i u m Engr Soc. Oct 1 971 :62. Van Dusen HA Jr. Street l i g hting l u m i na i re dirt depreciation. I l l u m inating Engineering. Feb 1 97 1 ; 66(2):122. R E F E R E N C E S FOR CHAPTER 9 1. National Electrica l Manufactu rers Association. N EMA 250, Enclosures for Electrical Equ ipment (1 000 Volts Maxi m u m). Rosslyn, VA: N EMA; 2008. 2. International Electrotechnical Commission. I EC 60529, Degrees of Protection Provided by Enclosures (IP Code). Geneva: IEC; 2009. 3. International Electrotechnical Comm ission. IE( 60598-1 :2020, Lum i n a i res - Part 1 : General req u i rements and tests. Geneva: I EC; 2020. 4. National Electrica l Manufactu rers Association. N EMA LSD 25-2008, Best Practices for Meta l H a l ide Lighting Systems. Rosslyn, Virg.: N EMA; 2008. 5. LampRecycle.org. O n l i ne: http://lamprecycle.org. (Accessed 2021 J u l 30). 6. RoHS Guide. Online: http://www.rohsguide.com/. (Accessed 2021 Jul 30). 9-25 Part 2 - Design H ig hways a n d I nterchanges Chapte r 1 0 CO N T E N TS 1 0.1 Roadway Lighting - General 1 0. 1 . 1 1 0. 1 .2 1 0-1 1 0.4.2 Hig hway I nterchanges . . 1 0- 1 1 0.4.3 Hig h-Mast Lighting . . . . . . . . . . . . . . . . . . 1 0- 1 . . . . . . . . . . . . . . The Pu rpose of Roadway Lighting 1 0.5 Hig hway Lighting Versus Street Lighting . . . 1 0.2 Classifications a nd Definitions . . . . . . . . . . . 10-2 1 0.3 1 0.2.1 Hig hway Defi nitions 1 0.2.2 Pavement Classification . . . . . . . . . . . . 1 0-2 1 0.6 1 0-3 1 0.3.1 Visual Task . . . . . . . 1 0.3.2 Glare, Light Trespass, . . . . . . . . . . . . . . . . . . 1 0.5.1 General . . . . . . 1 0.5.2 Lighting Criteria . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-8 . . . 1 0- 1 0 Recommended Calcu lation Methods . . 1 0.6.2 . . . . . . . . . . . . . . . . . . . . . . . . 1 0- 1 2 Recommended Luminance Calcu lation Method for Hig hways . . 1 0- 1 3 . . . . . . . . . . . . . . . . 1 0.3.3 The Effects of Headlig hts 1 0.3.4 Spectral Considerations 1 0-3 . . . . . . . . . . . 1 0-3 . . . . . . . . . . . . 1 0-3 Design Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-4 1 0.4.1 . . . 1 0-6 Design Ca lculations . . . . . . . . . . . . . . . . . . . . . 1 0-1 2 1 0.6. 1 1 0-3 . . . 1 0-5 Lighting Recom mendations . . . . . . . . . . . . . . 1 0-8 Design Considerations . . . . . . . . . . . . . . . . . . . 10-3 and Sky Glow Issues 1 0.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cu rves and Steep G rades . . . . . . . . . . . 1 0-4 1 0.7 Design Example - Freeway . • . . . . . . . . . . . . 1 0-1 3 Additional Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0-1 5 References for Chapter 1 0 . . . . . . . . . . . . . . . . . . . . . 1 0-1 5 Chapte r 1 0 H ig hways a n d I nterchanges T he primary purpose of this chapter is to serve as the basis for the design of fixed lighting for hig hways and interchanges. This chapter deals entirely with l ig hting design and does not g ive advice on construction. Its purpose is to provide recommendations for the design of new continuous or partial l i g hting systems for highways and interchanges. It is not i ntended for application to existing l ig hting systems u ntil such systems a re com pletely redesigned. It has been prepared to advance the art, science, and practice of hig hway l ig hting in North America. I n those c i rcu mstances where there is a ny doubt as principal pu rpose of roadway (street and hig hway) to whether the provision of new or u pdated roadway l ig hting is to a l low accu rate and comforta ble visibil ity l i g ht i n g would provide a benefit at a partic u l a r at night of possible hazards i n sufficient time to a l low l ocation, a decision s h o u l d b e m a d e based o n a a ppropriate action. For the d river of a motor vehicle, study of local con ditions. In the U n ited States, the AASHTO Lighting Design Guide provides g u ida nce for warranting.1 In Canada, the TAC Guide for the Design of Roadway Lighting includes g u idance for warranting.2 O n ce a decision has been made to provide l i g hting, this Recommended Practice may be referred to for this wi l l mean time to stop or to ma neuver a round an obstacle. Properly designed l ighting has been shown to sign ifica ntly reduce the proportion of accidents (col l isions) that occ u r at nig ht, especia lly on u rban freeways and streets. g u ida nce in desig ning an appropriate roadway l i g hting 1 0.1 .2 Highway Lighting Versus Street Lighting. Two system. d ifferent types of roadway l i g hting systems a re defined This chapter contains lighting design considerations in this Recommended Practice: hig hway l ighting and and criteria specific to l i g hting for hig hways a n d street lighting. interchanges. I ncluded i n t h i s chapter a r e coverage of highway classifications and pavement classifications. Streets are covered separately in Chapter 11 because of the potential presence of pedestrians and bicyclists. Beca use of the special considerations in herent in their d esign, i ntersections, including Highway lighting (see, for example, Figure 1 0-1) refers to l i g hting that is provided for freeways, expressways, l i m ited access roadways, and roads on which pedestrians, cyclists, and parked vehicles a re genera l ly not present. rou n d a bouts, a re The primary purposes of highway l ig hting are to help covered in Chapter 12, railway crossings in Chapter 1 3, the motorist remain on the hig hway and help with the underpasses and tunnels in Chapter 14, and tol l plazas detection of obstacles with in and beyond the range of in Chapter 1 5. the vehicle's headlights. In addition, several types of off-roadway a pplications Street lighting (see, for example, Figure 1 0-2) refers to and facil ities are covered in Chapter 1 6, parking facilities in Chapter 1 7, roadway sign l i g hting considerations in Chapter 1 8, and temporary and work zone lighting considerations i n Chapter 1 9. l ig hting that is provided for major (arterial), col lector, and local roads, where pedestrians and cyclists are genera l l y present d u ri n g h o u rs of d a rkness. The pri mary pu rposes of street l ig hting a re to help the motorist identify obstacles, provide adeq uate visibility of pedestrians and cyclists, and assist i n visual search 1 0.1 Roadway Lighting - General tasks, both on and adjacent to the street. Street l i g hting 1 0.1 .1 The Purpose of Roadway Lighting. The is covered i n Chapter 1 1 . 1 0-1 ANSl/IES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Figure 10-1 . Typical highway lighting installations. (Images courtesy of Kim Molloy, WSP; and Chris Leone, WSP) Figure 10-2. Typical street lighting installations. (Images courtesy of Paul Lutkevich, WSP) 1 0.2 Classifications and Defi nitions should best fit the descriptions contained with in this The terms used in this docu ment m ig ht be used and document and not those of other sou rces. defined differently by other docu ments, zoning bylaws, b u i l d i n g codes, and agencies. For l i g hting design 1 0.2.1 Highway Definitions. pu rposes, the classification for a n area or roadway Freeway: A divided highway with fu l l control of access. 1 0-2 Highways and I nterchanges Freeway A: Roadways with g reat visual complexity Recommended Practice a re for typical situations. If the and high traffic vol u mes. This type of freeway wi l l designer notes unusual situations when considering usua l ly be found i n major metropol itan areas in or these items, then reasonable eng ineering judg ment near the central core, and will operate at or near should be applied when applying the recommendations design capacity thro u g h some of the early morning in this docu ment. or evening hours of darkness. 1 0.3.2 Glare, Light Trespass, and Sky G low Issues. Freeway 8: All other d ivided roadways with fu l l Roadway l ighting systems a re under i ncreasing scrutiny control o f access. from various sectors of the public. While the public is not usually aware of specific design req u i rements Expressway: A d ivided h i g hway with partial control of of roadway l i g hting systems, observations of g l a re, access. light trespass, and sky g low are widely perceived and might be subject to criticism. Lighting designers should Isolated I nterchange: A g rade-separated roadway become fam i l ia r with these issues and be prepared to crossing with one or more ra mp connections between design a lighting system that meets the needs of the the crossing roadways, which is lig hted and is not part client or owner, while also considering the possible of a contin uous roadway lighting system . effects of the lighting system on the environ ment. The red uction of spill l i g hting should, however, be weighed Median: The portion o f a divided roadway physica l l y agai nst the need for proper surround l i g hting, as these separating the traveled ways for traffic in opposite two e lements need to be balanced and coordinated directions. with each other. 1 0.2.2 Pavement Classification. The calcu lation of These issues are discussed in deta i l in Chapter 4 either pavement l u m i nance or Small Ta rget Visibility Obtrusive Light. (STV) req u i res information about the directional su rface reflectance characteristics of the pavement. Studies 1 0.3.3 The Effects of Headlights. have shown that most common pavements can be the primary system intended to assist d rivers with g rouped into a l i m ited nu mber of standard road su rfaces see i n g objects on and along the road. The abil ity of H ead l i g hts a re having specific reflectance characteristics. These data hea d l ig hts to provide for detection of objects at higher have been experimental ly determi ned and presented vehicle speeds may not be adequate. It is known that in r-tables. (Refer to Section 3.1 .5 for a description of at higher speeds the stopping sight distance (SSD) the pavement classifications and Section 3.3.1 for the can exceed the visual detection dista nce provided r-ta bles.) by low-beam headlig hts.4'5'6 (See Chapter 3, Section 3.1 .8 for additional i nformation.) ( Refer to the AASHTO Roadside Safety Guide1 or the TAC Geometric Design 1 0.3 Design Considerations Guide for Canadian Roads2 for information on calculating stopping sight distances.) 1 0.3.1 Visual Task. An effort should be made to completely understand the visua l task in a g iven setting.3 1 0.3.4 Spectral Considerations. Research in the a rea of Too often, the designer thi nks o n ly i n terms of the visibility has recently found differences in the detection d riving task. When desig n i ng for areas of congestion or distances of objects and pedestrians under various CCT significant interest, a l lowance needs to be made for the light sources. While earlier research using achromatic myriad tasks that may be present. On a hig hway, these targets indicated no difference i n performance when could include detecting wildl ife approaching the road, comparing sou rce color,7 more-recent reports using spotting hazards or obstructions on the road, dealing the more rea l istic condition of colored targets ind icate with traffic tie-ups, reading signs, and other possible spectrum can play a role in affecti ng detection d istance. d riving tasks. The recom mendations included i n this The Northwest Energy Efficiency Alliance Report 1 0-3 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities E 1 4-286, Seattle LED Adaptive Lighting Study8 (refer to ana lysis. Poles should be l ocated so as to provide Section 7.3 in that d ocument) states, "The user field test adeq uate clearance behind the g u i dera il or any natura l demonstrated that the 41 00K test a reas, including the barrier, if s u c h exists. asymmetric test a reas, outperformed all other test a reas in terms of detection distance," and NCHRP Research 1 0.4.1 .2 Luminaire Orientation on Cu rves. Proper Report 940, Solid-State Roadway Lighting Design Guide,9 horizontal orientation of l u m inaire supports and poles which showed increases i n detection distances at both on c u rves is i mportant to ensure a balanced distribution researched test speeds (35 and 55 m i/h) and higher of the l ig ht flux on the pavement. This can be achieved surround ratios with 4000-K sou rces. The NCH RP report by ensuring that the l u m i naire is oriented at 90 degrees states u nder Effect of Light Type (Final Report, p. 83), to the tangent of the cu rve (see Figure 1 0-3). "There was, however, a practical difference for 4000 K, which had greater detection distances especially for 1 0.4.1 .3 Luminaire Orientation on Steep Grades. pedestrians, than a ny of the other l ig ht sources." When luminaires are located on steep g rades, it might The l u m i na nce l evels in Table 1 0-2 (see Section 1 0.5.2) were developed for roadway l ocations in the d i rect line be necessary to orient the l u minaire (a "ro l l " adjustment) so that the l i g ht pattern from the l u m inaire is centered of sight of the observer and assume photopic vision. Therefore, mesopic factors a re not applicable. 1 0.4 Design Issues Several major issues affect d river vision differently in rural compared to u rban areas, and on l i m ited access vs. u n control led access roads. These include differences in speed and levels of background l u m i nance. Because of the increase in vehicular traffic and the level of traffic control, a motorist's rate of travel is typica l ly s lower i n u rban a reas. T h e hig her levels o f background lighting found in urban areas can augment roadway l u m inance and i l l u m i na nce provided by lighting systems, but can a lso produce reduction i n visibility due to glare and distraction. Thus, off-road light sources can either improve or impair the vision of d rivers. 1 0.4.1 Curves and Steep Grades. The visual problem in d riving increases on cu rves and steep g rades. Sha rper­ radius cu rves and steeper grades can req u i re closer spacing of l u minaires in order to achieve the desired light levels and u niformities. The modern computer programs that are ava ilable a l l ow the designer to adjust and refine the pole spacing on curves and grades as required, to ensure that the lighting criteria are satisfied throug hout. 1 0.4.1 .1 Luminaire and Pole Location. The geometry of abrupt cu rves, such as those found on traffic interchanges and many roadway a reas, requires careful 1 0-4 Figure 10-3. Luminaire orientation on curves. Highways and I nterchanges a bout the axis of the l u m i naire. This is accomplished 1 0.4.2 by leve l l i ng the l u minaire to the g rade of the road. This i l l u m i nance that revea ls t h e features o f t h e entire ensures better uniformity of light distribution and keeps scen e will aid in d river detection of hazards. An g l a re to a m i n i m u m (see Figure 1 0-4). inadequately lit interchange can lead to confusion for :_urv�� poxw r: Typical Angle ofMaximum Candle Sag - � - � /I I nterchanges. S u rro u n d i n g the driver, by g iving mislead ing information due to a ra ndom placement of the l u m i naires. Severa l types of . . . m a re m i � :��� ......._ H i g hway Normal to Curve or Grade Line ....... interchanges are shown in Figure 1 0-5. When continuous lighting of the entire interchange area is not provided, it might be desirable to extend the limits of the conflict area to include site-specific areas of complexity, such as points of access and egress, curves, and steep hills. In these cases, partial lighting should Figure 10-4. Luminaire orientation on steep grades. extend beyond the conflict areas. The reasons for this are: Underpass/Overpa.ss A D Fully Directional Figure 1 0-5. Illumination of high-speed, high-traffic-density interchanges. Highway complexities: (A) underpass­ overpass: and (B) to (E) interchanges. Note: Arrows indicate traffic flow directions. 1 0-5 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities • The eyes of the d river, adapted to the level of the of freeways, parking lots, rest a reas, and tol l plazas, l i g hted a rea, need about one second to adjust to particu la rly where the poles can be safely mou nted the changes in the l ighting upon leaving the lig hted on concrete med ians or in g rass or dirt medians of area, to maintain vision d u ring the period of dark sufficient width outside of the clear zone. adaptation. Lighting transition, however, should be beyond the end of the conflict area. (Refer to 1 0.4.3.1 Benefits. Several benefits are derived from the Section 1 0.5.2.2 Partial Lighting for additional application of a hig h-mast lighting system: information.) • • • The l ig ht from such a system is designed to provide i l l u m ination of the roadway as well as the a reas Traffic merging i nto a highway from a n access road is often slow in accelerating to the speed on the im mediately beyond the roadway. This is in sharp highway. The lighting along this area for a distance contrast to a conventional l ig hting system, 20 meters beyond the access point extends visi b i l ity and (66 ft) or less in height, which in herently tends to facilitates the acceleration and merg i ng process. concentrate or d i rect a g reater portion of l u m i nous However, entrance ram p l ighting is not req u i red for fl ux mainly onto the traveled roadway. Since high­ the redesign of an existing interchange with partial mast lighting tends to i ll u m i nate the entire traveled interchange l ighting when nighttime crash data corridor within the road a l l owance, it is conceivable show it is not needed. (Refer to Section 1 0.5.2.2 that it therefore provides g reater visual comfort Partial Lighting for additional i nformation.) to the trave l i ng motorist by i mproving peripheral vision and by better i l l u m i nati ng roadside obstacles, Diverg i n g traffic lanes should be g iven careful fixed structu res, and other s i m i l a r objects that consideration because motorists a re most likely to can be just in the field of view of a driver. This is become confused in these areas. 1 0.4.3 High-Mast Lig hting. achieved by more-effective control of glare and by an im provement in the d river's orientation. H i g h -mast l i g hting provides a means of providing both partial and • col lisions may be as wel l . continuous hig hway i l l u m ination (see, for exa m p l e, Figure 1 0-6) with a m i n i m a l n u m ber of poles. Such Pole c lutter is reduced, and therefore car-pole • The location o f poles (typically in the m edian o r a g reater distance from traffic lanes) c a n mean systems consist of poles that ra nge i n excess of 20 meters (approximately 66 ft) in height and can consist that routine maintenance work can be carried out of clusters of 3 or more l u m i na i res that are usually without i nterference to traffic operations. located in a symmetrical fashion on su pporting brackets • Specialized vehicular l ift eq uipment is not required that are fastened onto a ring. This type of hig hway for mai ntenance work for hig h-mast l i g hti ng l ighting system can be ideal for providing i l l u mination systems equ ipped with Figure 1 0-6. Examples of high-mast roadway lighting. (Images courtesy o f P a u l Lutkevich, WSP) 1 0-6 l oweri ng devices, as Highways and I nterchanges compared to conventional l ighting systems, thus reducing maintenance and service costs. 1 0.4.3.2 Design Considerations. When designing a • Spill light beyond the right of way • Perceived brightness Spill light can be defined as unwa nted l ight that spills high-mast lighting system, it shou l d be determi ned beyond the right of way. This l ight is wasteful and can whether the use of such a system is economically cause a n noyance to residences adjacent to the hig hway justifiable, or whether a conventional l i g hting system property line. can ach ieve the establ ished roadway l ig hting criteria at lower cost and with g reater efficiency. One of the main components of discomfort glare is In u rban a reas with l i m ited hig hway right of way of the surface luminance of the l u minaire in a given and residences in close proxim ity to the hig hway, it d i rection, and it is a factor contributing to reti nal might be advantageous to consider a combi nation of i l l u m inance. Both of these criteria are quantifiable and the traditional conventional l i g hting and hig h-mast measurable. lu m i nous intensity. Luminous intensity is a function i l l u m i nation. The use of conventional l ig hting can serve to reduce, if not e l i m i nate, the vexing problem of l ight Hig h-mast lighting inherently tends to contribute to trespass and perceived brig htness that are characteristic light trespass because of the higher m o u nting height of a h i g h - mast lighting system . H i g h-mast l i g hting and m u ltiple clusters of l u m i naires employed in the is proba bly not suitable for these areas; if it is used, design process. With high-mast lighting, the poles are measures should be considered to abate light trespass up to 50 meters in height and there are up to twelve and to mitigate the source brig htness issue (bright l ight lu m i naires on each pole. G reater pole height means that sou rces on tal l poles set adjacent to a dark background). the pole towers a bove the right of way and in doing so 1 0.4.3.3 Ca lculations. Hig h-mast i l l u m i nation can be such a large n u m ber of high wattage la mps closely scatters its light over a large a rea. In addition, having designed to meet l u minance criteria for straight sections packed into one small a rea can create a potential glare of h ig hway and i l l u m inance criteria for curving roads sou rce. and for interchange ram ps, si nce the d river's direction of sight is conti nually changing. Light spi l l and perceived brightness can be controlled by using "light l i miting devices" such as: Opinions differ on whether l ight levels can be lowered • Shields • Shrouds • Va ria ble-optics l u mi n a i res with adj ustable l i g ht when high-mast-l ighting is used, compared with the use of conventional l i g hting. Typically, the su rround conditions are more evenly i l l u m inated with the high-mast patterns design, and seeing is easier. However, adequate research to justify the lower light levels has not been conducted. Regardless whether high-mast or conventional systems 1 0.4.3.5 Economics. are employed, the same lighting design criteria, such as available to system desig ners, it is i mportant to eva luate light levels and uniformity ratios, should be used. i l l u m i nation system i nsta l lations i n a sound a n d 1 0.4.3.4 Environmental I m pacts. are considered. With a ra nge of e q u i p ment consistent manner, where both safety and economics Light trespass may be defined as l i g ht incident outside the a rea to be l it, which because of qua ntitative, d i rectional, or spectral The economic considerations of high-mast l ig hting attributes in a given context gives rise to annoyance, systems are: d iscomfort, d i straction, or reduced abi l ity to see • essential information. Light trespass from a fixed high­ mast lighting system can be separated into two major components. These are: Fewer poles a re req u i red, as com pa red to conventional lighting systems. • Specialized l ift e q u i pment is not req u i red for mai ntenance work for hig h-mast systems as 1 0-7 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities • compared to conventio n a l systems if l owering system. Because the a mount of l i g ht seen by the d river systems a re i ncluded as part of the desig n. is the portion that reflects from the pavement toward H i g h-mast l ig ht poles can be insta l led further away the d river, and because different pavements exhibit from the traffic l anes, red u ci n g or e l i m inating varied reflectance characteristics, d ifferent i l l u m ina nce vehicle pole coll isions with poles. • Based on equal i II u mi na nee levels, h ig h-mast I ig hti ng systems consume more energy as com pa red to a conventional lighting system. The i nitia l equipment costs of hig h-mast lighting systems are g reater than those of conventional lighting systems. • H i g h-mast systems req u i re less g rade work along the traffic way a n d therefore can reduce the installation cost of new roadway l ighting systems. It is necessary to evaluate the econom ics of each levels are needed for each type of standard roadway su rface. l l l u m inance is easily calcu lated and measu red a n d is not observer or pavement dependent. The STV method of design is based on the visibil ity levels of a n array of small targets on the roadway, and considering the fol l owing factors: • The l u minance of the targets • The l u minance of the im mediate background • The adaptation level of the adjacent surroundings • Disa bility g lare alternative sound ly and consistently by including the fol lowing key factors: The STV value is a weighted average of the visibility Relevant costs level (VL) of these targets. This method • Time va lue of money u ndergoing eva l uation but m ig ht be a valuable tool • I nterest rates • is sti l l when comparing the expected results of two designs del ivering approximately the same l u m inance and • Discount rates • Life cycle costs • A tech nique for performing life cycle cost analysis Figure 1 0-7 shows two relatively similar l u m i na nce of hig hway l i g hting system a lternatives des igns, but the h igher STV va lue of the road on the left i l l u m inance performance. also seems to indicate better ta rget visibil ity of rows of targets on the roadway. 1 0.S Lighting Recom mendations For this Recommended Practice, l u m i nance is the selected 1 0.5.1 General. This document includes three different design method for straight highways and streets, horizontal methods for use in eva l u ating different aspects of and vertical illuminance comprise the selected method for continuous highway and street lighting design. These are pedestrian areas, and horizontal illuminance is used for l u minance, illuminance, and smal l target visibility (STV). intersections and interchanges. The luminance method of roadway lighting design Horizontal i l l u m i nance shall be used on cu rved sections determines how "bright" the road appears by determining of roads and streets, where l u m i na nce is not suitable the amount of light reflected from the pavement in the d u e to l i m itations of the r-ta bles. Cu rved roadway direction of the d river. It uses the reflective characteristics sections (less than 600-meter radius) or roads with steep summarized in the r-tables for the standard roadway a n d variable g rades (6% or g reater) shall be calculated su rface types and a specific observer position (see using the horizontal i l l u m inance method. Chapter 3, Section 3 2 .3 .1 2). It is measured with a . . l u minance meter by the method described in Annex A. For determ i n i n g what horizontal i l l u m i nance l evel should be used on c u rved roads, the fol l owing The illuminance method of roadway lighting design equ iva lencies may be used (it is i mportant to note that determines the a mount of light incident on the roadway these equ iva lencies a re not conversion factors and su rface or on vertical su rfaces from the roadway lighting only provide a roug h approximation to use in these 1 0-8 Hig hways a nd Interchanges Figure 1 0-7. Target visibility with similar luminance designs. (Images cou rtesy of James Havard) more complex geometric areas): 1 cd/m 2 for 1 0 lux on be evaluated with the necessary engi neering study. For R1 pavement; 1 cd/m2 for 15 l ux on R2 or R3 pavement; exa mple, if it is decided to reduce the recommended and 1 cd/m2 for 1 3.3 lux on R4 pavement. The same va l ues by half (sometimes erroneously referred to as u niform ity ratios shall apply for i l l u m i na nce as for "ha lf-code" lighti ng), it can not be assumed the benefit l u m i na nce. Vei ling l u minance is not a design criterion is a lso half. If the u niformity val ues or glare val ues are for cu rved roads. twice the recom mended va l ues, visibility m i g ht be severely hampered instead of sim ply being half of what Field val idation of a lighting system's performance may it would be. Reductions should only be considered in be done with l u minance or i l l u mi nance. (See Section the context of adaptive l i g hting, as described i n Section 5.6 - Field Verification for additional i nformation.) 5.2.8. I n street and hig hway l i g hting, vei l ing l u m i na nce, Other Lv, is the metric used to evaluate d isabi lity glare as recommendations include: experienced by the driver. Stray light within the eye, • produced by l ight sou rces i n the field of view, effectively • decreases the apparent contrast of objects agai nst their shall be a p p l yi n g l i g hted as these per their When a specifying authority selects a specific BUG rating (see Section 2.6.3) for a particular hig hway's background and can someti mes cause visual d iscomfort. l u m i n a i res, this shall not serve to com promise In Table 1 0-1 (see Section 1 0.5.2.1 ), the criterion for the design criteria as determined by the hig hway li miting glare is expressed as the vei l i n g l u minance Design Classification. H owever, where the g lare (G) ratio, which is the vei l i n g luminance maxi m u m divided part of the BUG rating and the vei ling l u minance by the average l u m ina nce of the road su rface. In this (Lv) calcu lations conflict, then com pliance with the way, l u m i naire "brightness" is considered in the context veiling l u m i nance ratio criterion shall take priority. of the "brightness" of the road su rface as seen by the • Envi ronmental L i g hting Zones sha l l have no influence in the selection of the proper Hig hway Classification. The lighting recom mendations given in this chapter are m i n i m u m val ues (or maxi m u m for u niformity and vei l i ng hig hways when classification, as determ i ned by the proper warrants. su perim poses a "veil" of l u m i nance on the retina. This d river. All consid e rat i o n s • Ambient contributions from l ig hting off the street l u m i nance ratios) arrived at thro u g h practical experience that are not due to the highway l i g hting system a nd ag reed upon by consensus of the IES Roadway shall not be considered in the lighting calcu lations. Lighting Committee. Variations and exceptions to the values a re not addressed in this docu ment a nd should • H i g hway lighting design shall be restricted as much as possible to the roadway a rea. 1 0-9 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities • Off-road l i g hting insta l l ations shall take i nto warranted (refer to AASHTO Roadway Lighting Design consideration a ny adjacent highways so as not to Guide1 or the TAC Guide for the Design of Roadway create a ny safety issues for d rivers. Lighting2 for warranting information). Partia l l i g hting consists of a l i g hting system that is put 1 0.5.2 Lighting Criteria. in place to provide i l l u m i nation at points of potential 1 0. 5 .2.1 Conti n u o u s Lighting. H i g hway l i g h t i n g conflict. It is not considered continuous, but some of the is provided for roads that a re n o t i ntended t o have rules that a pply to continuous lighting will a pply in the s i g n ificant (if a n y) pedestria n or cyc l i s t activity. design of partial lighting, such as pole placement and These roads a re genera l ly l i m i ted -access roadways, calcu lation proced u res. s u c h as freeways and exp ressways. The l u m i n a n ce m ethod is reco m m ended fo r d e s i g n of h i g hway In the case of isolated i nterchanges, the conflict area is l i g h t i n g . The reco m mended l i g ht i n g d e s i g n criteria the a rea from the bifurcation point to points on both for conti n u o u s l y lit h i g hways a re provided i n Ta ble the ramp and the thro u g h roadway. (See Figures 1 0-Sa 1 0-1 . and 1 0-Sb). The reader may notice that the l u m i nance criterion for expressways is higher than that for either of the freeway types, even though the expressway speed l im its tend to be lower. The reason is the additional complexity in herent in expressways, as manifested in an increase in points of conflict due to the presence of intersections and sometimes even d riveways. It is recommended that i ll u m i na nce calcu lations a lso be performed for the resultant design to provide val ues Partia l lighting should meet the l ighting criteria for the type of road where the i nterchange is located. Isol ated i nterchanges should meet the l i g hting recommendations for partial intercha nges. The val ues i n Table 1 0-2 a r e t h e recom mended average mai ntained i l l u m inance l evels, based on road classification. Table 1 0-2. llluminance Criteria for Partial Interchange Lighting that can be used for field val idation of the performance of the insta l led l i g hting system . Uniformity Road R1 R2, R3 R4 Classification Lux (fc) Lux (fc) Lux (fc) 6.0 (0.6) 9.0 (0.8) 8.0 (0.7) 3.0 4.0 (0.4) 6.0 (0.6) 5.0 (0.5) 3.0 6.0 (0.6) 9.0 (0.8) 8.0 (0.7) 3.0 Freeway, 1 0.5.2.2 Partial Lighting. Class A Freeway, General: Class B Partial i ntercha nge l i g hting is sometimes used on Expressway freeways and highways when continuous l i g hting is not Ratio favn/fmin Table 1 0-1 . Lighting Design Criteria for Highways Average Luminance Average Uniformity Maximum Maximum Veiling Ratio Uniformity Ratio Luminance Ratio (cd/m 2 ) Lav)L mln Lma/L mln Lv ma/L avn Freeway Class A 0.6 3.5 6.0 0.3 Freeway Class B 0.4 3.5 6.0 0.3 Expressway 1 .0 3.0 5.0 0.3 Road Classification Lavg Table notes: Lavg: Maintained average pavement l u m ina nce L m;n: M i n i m u m pavement l u m inance Lv, max: Maxi m u m ve iling l u m i nance 1 0-1 0 Highways and I nterchanges with Area of illuminance calculation.cakulation area includes ramp araa along outside lane. Point on ramp width whe"' full ramp ends. - - - ---.- -- � -· - _ .-..... '!.::-�=- =�--=�-�--::� �-�� ----= = l==-=:.--=--=--=---=--� -- - -.•,_ ---�----_ Optional light pole located up ramp. spaced same as between poles Pl and P2 Mey not be necessary due to ramp design speed or geometrics. - - - - -- -- ...-...- - - l.---location Light Pole P3 located da.vnstream, spaCl!d same as between poles Pl and P2 Light poie P2 located downstream, with dictated ll'f recommended value as well as Avg/Min ratio Light poie Pl placed at ramp taper point, which is point at which entrance ramp width begins to narrow Figure 1 0-Sa. An example of partial lighting for an entrance ramp. Optional light pole, depending Light pole Pl placed on ramp radius, speed, and other factors. Spacing same as a closer spacing may be needed on a tight-radius ramp. Light pole P2 located upstream, with at gore point, lighting between poles Pl and P2, but location dictated by recommended the physical obstruction. :: ::: • :; :�;:,;:�� 4 •P Pl 0 value as well as Avg/ " Min ratio. Spacing shall be the same as between d P2, depe din Pl an in accordance with g on ramp alignment and exit ramp visibility. -- HIGHWAY Optional li ght pole placed n Optional lig ht pole located upstream. Area of ii luminance calculation in green. road authority roadside safety practices. Figure 1 0-Sb. An example of partial lighting for an exit ramp. Exit ramps: or where safety concerns have been identified. These The extent of partial l i g hting at exit ra m ps will poles should be positioned so that both the rig ht vary depen ding on the site-specific g eometry and thro u g h lane and the exit ra mp are l i g hted. cha racteristics of each exit ramp. The l u minaires and light poles should be located as shown i n Figure 1 0-Sb. 1 0.5.2.3 Surround Ratio (SR). Research performed for NCHRP 940, Solid-State Roadway Ligh ting Design The gore area should be l i g hted as shown in Figure 1 0-Sb. Pole Pl should be located at the critical point within the gore area, just up-ramp from the physical obstruction. Another pole (P3 in the diagra m) should be provided along the m a i n l i ne to identify the contin uation of the right through lane. The P3 pole should be located "downstrea m " of the gore in accordance with the applicable road a uthority's roadside safety practices. Guide9 shows that a d river's object d etectio n d istance is i n creased when l i ghting is present in a reas adjacent to the roadway (referred to as the surround). This methodology is also used i n the I nternationa l C o m m ission on I l l u m i nation (CIE)'s recom m endations. CIE has recently renamed S R as edge illuminance ratio (EI R), a n d it c l osely re l ates to the surround ratio A pole (P2 in the diagra m) should be located at the method ology d iscu ssed in this section. Therefore, SR bifurcation point or as far upstream from pole Pl as s h o u l d be considered a design m etric. When travel possi ble while sti l l meeting the partial lighting criteria. is i n two d i recti ons, the s u rro u n d a rea i s on the right An optional pole (P4 i n the diagra m) may be added for s i d e of the road (see Figu res 3-6 through 3-8 in exit ra mps with a relatively high rad i u s of cu rvature Chapter 3). 1 0-1 1 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities The SR criterion should be 0.8, which is ratio of the of additional average i l l u m i nance of the surround a rea adjacent considered. roadside equ ipment should be to the travel way (3.6 m [12 ft] wide) to the average i l l u minance of the travel lane itself. For example, using the configuration shown in Figure 1 0-9, the average i l l u m inance of the area shown as the surround (S) divided by the average i l luminance of the adjacent lane (T) should be 0.8 or greater. 1 0.5.2.4 An Alternative Method for Determining Lighting Criteria. The methodolog ies used i n Section 1 0.5 and its subsections do not provide a means for determ ining a lternative lighting levels when using a n adaptive lighting system, i n c l u d i n g d i m m ing t o lower levels for times of low traffic volu mes or other cha nged conditions. An a lternative process for determination of appropriate roadway lighting design criteria, based on the a n a lysis of crashes and l i g hting performance, is defined i n Annex K Figure 10-9. Example diagram for applying surround ratio (SR). (Note: The width of the surround is always 3.6 m, even if the roadway shoulder is wider or narrower.) - Alternative Lighting Criteria Selection Methodology; a series of conditions are described and associated lighting design criteria developed to provide a n a pproach for light level selection, including adj ustab i l ity of the light level based on changing needs The appl ication of su rround ratio has led to i m p rove­ of the driving environment. ments in the detection distances of objects on and adjacent to the roadway. There a re situations, however, where the bala nce and need for these visibi l ity improve­ ments should be considered along with any potential negative impacts. Some of these situations incl ude: • • • 1 0.6 Design Calculations Refi nements i n computer roadway l i g hting design software have changed the way a lighting desi g n is Residential local roads where pedestrian vol u mes undertaken. Today's computer hardware and software are low and l ower speeds a l low objects to be with in a l low a desig ner to q uickly run m u ltiple calcu lations and the useful range of head lig hts for detection refi ne l i g hting layouts. Variables can now be cha nged R u ra l roundabouts where pedestrian and cyclist and a new calcu lation completed i n a matter of m i n utes vol u mes are low or seconds, a l lowing the desig ner to try num erous Identified environmenta l l y sensitive areas where com binations in a n efficient manner. the lighting of the a reas immediately adjacent to • • • the travel lane will have damaging im pact 1 0.6.1 Recommended Calculation Methods. Three Bridges or structures that do not have shoulder or methods a re typical ly available in computer software sidewa l k areas extending 3.6 meters or more from for those perform i n g roadway l ig hting calculations. the edge of the travel way They a re the l u minance, i l l u m i nance, and STV design Streets where sidewal k l ighting is provided, as methods, as defined i n Chapter 3 the sidewa l k lighting wil l likely produce the same design software will make calcu lations and provide visibility improvements results using a l l three methods. - Calculations. Most The designer should consider situations were meeting the su rround ratio req u i rements req uires For highway and intercha nge lighting, the recom mended additional roadside hazards (e.g., additional poles method of calcu lation is luminance. The designer sho u l d on very wide roadways). The bala nce between make desig n decisions and adjust variables t o meet the the safety benefits of SR and the safety hazards l u m i nance req u i rements for the hig hway. 1 0-1 2 Highways and I nterchanges l l lu m i na nce levels can also be determi ned for com paring Step 3: Select equipment calcu lated levels with field measurements. (For more For this roadway, the owner has requested that light information, refer to Section 5.6.2 trespass and glare be m i n i mized, so the BUG rating for - Field Verification.) the l u minaire selected will have a low G rating. Double­ 1 0.6.2 Ca lculation davit, median mou nted poles, 1 2.0 m in height will be Method for Highways. Lighting design for the hig hway Recom mended Lumina nce used. Barriers are being added to the roadway, so the should be u ndertaken using the recommended four­ clear zone is not a design issue. The l u m i naire selected step calcu lation approach shown below. will be d ictated by the owner in order to m i n i mize • Step 1: Establish l ighting design criteria. req u i red spare parts and will be a n LED flat-lens cobra­ • Step 2: Defi ne road geometrics (road and l a ne head style l u m i naire. widths). • Step 3: Define va ria ble e l ements and esta b l ish the layout (refer to Section 10.3 - Design Considerations). • Step 4: Through a "trial-and-adjustment" process u s i ng computer design software, meet or exceed t h e maintained average l u m inance a n d average-to-min i m u m a n d maxi m u m -to-mi n i m u m u n iformity ratios, as wel l as t h e veiling l u m inance recommendations listed in Section 1 0.5 -Lighting Recommendations. Calculation g rid placement and point spacing a re d iscussed in Chapter 3, Section 3.2.3. Step 4: Calculate Using computer design software, layouts are calcu lated in accordance with Section 5.4.4 - Perform Lighting Design. The com bination of pole heig ht, spacing, l u m i naire distribution, and lumen output that meets or exceeds the m i n i m u m recommended va l ues should be compared from an economic standpoint to determine the most cost-effective a lternative that meets the owner's needs. Step 5: Determine pole layout The pole layout for this freeway should beg i n at overpass structu res that w i l l l imit pole placement. An exa mple wou ld be at a n overpass structure where the first pole can be placed 1 2.0 m from the structure to 1 0.7 Design Example - Freeway The fol lowi n g step-by-step descriptions i l l ustrate the process that a l i g hting desig ner wou ld fol l ow to determine the l ighting layout for this freeway lighting exa mple. (Refer to Chapter 5 - The Planning and Design Process for more i nformation.) Figure 1 0-1 0 shows a sample lighti n g ca lculation output for this exam ple. reduce shadows. The pole spacing is then adjusted to suit the actual distance between i nterchanges and other obstacles. The calcu lations are then performed again to reflect this new pole spacing, making sure the criteria are stil l achieved. It is i mportant to note that close coordination needs to take place with the hig hway designer to achieve proper pole layout; smaller isolated obstructions l i ke culverts, signs, or reta i n i ng structu res will req u i re i ndividual adjustments of poles. Step 1 : Determine roadway features The roadway is a freeway. It consists of two la nes in each direction with a 3.0-meter median. Step 2: Select lighting criteria From Table 1 0-1, the recommended val ues are: • Average Luminance (cd/m2): 0.60 • Average-to-M i n i m u m U niformity Ratio: 3.5:1 • Maximum-to-M i n i m u m U niformity Ratio: 6.0:1 • Maxi m u m Vei l i ng Luminance Ratio: 0.3:1 1 0-1 3 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities LUMI NAIRE POLE (TYPICAL) � ROADWAY HORIZONTAL LUMINANCE OUTPUT RESULTS GRID HORIZONTAL LUMINANCE MAINTAINED AVERAGE UNIFORMITY UNIFORMITY LUMINAIRES RATIO RATIO SPACING (AVG./MIN.) (MAX./MIN.) 5.9 cd/m.sq LUMINAIRE POLE (TYPICAL) 7Bm � ROADWAY VEILING LUMINANCE OUTPUT RESULTS MAXIMUM VEI LING LUMINANCE RATIO (LV/LAVG .) Figure 10-10. Sample roadway calculation: freeway. 1 0-14 0.3 Highways and I nterchanges A D D I T I O N A L R E AD I N G Note: This section is not part o fANSI/JES RP-8-27. It is included for informational purposes only. In addition to those found in the References section, the fol lowing items may prove usefu l. American Association of State Hig hway and Tra nsportation Officials. AASHTO GL-6-2005, Roadway Lighting Design G uide, 6 th ed. Washington, DC: AASHTO; 2005. Federal Highway Ad ministration. FHWA-SA-1 1 -22, FHWA Lighting Hand book. Washi ngton, DC: FHWA; 201 2. I ll u m i nating Engi neeri ng Society. ANSI/I ES LP-4-20, Lighting Practice: Electric Light Sources - Properties, Selection, and Specification. New York: I ES; 2020. I nternational Commission on I l l u m ination (CIE). CIE 1 9 1 :201 0, Recom mended System for Mesopic Photometry Based on Visua l Performance. Vien na: CIE; 201 0. R E F E RE N C E S FOR CHAPTER 1 0 1. American Association of State and Hig hway Tra nsportation Officials. AASHTO Roadside Design Gu ide, 4th ed. Washington, DC: Federal H i g hway Ad ministration; 201 2. 2. Transportation Association o f Canada. Guide for the Design o f Roadway Lighting. Ottawa: TAC; 2006. (PTM­ LIGHTI NG06). 3. I nternational Commission on I l l u m i nation (CIE). CIE 1 00-1 992, Fundamenta ls of the Visual Task of Night Driving. Vienna: CIE; 1 992. 4. J M U Office of Public Safety. Detection and Safe Stopping Distances. H arrisonburg, Virg.: Ja mes Madison University; Oct 2009. 5. Roper VJ, Howard, E A . Seeing with motor car headlamps. Tra ns I ES. 1 938;33(5):417-38. 6. Johansson G, Rumar K. Visible distances and safe approach speeds for night d riving. Ergonomics. 1 968;1 1 (3):27582. 7. Northwest Energy Efficiency Alliance. Seattle LED Ada ptive Lighting Study. Portland, Ore.: N EEA; 201 4. (NEEA Report #El 4-286). 8. Northwest Energy Efficiency Alliance. Seattle LED Ada ptive Lighting Study. Portland, Ore.: N EEA; 201 4. (NEEA Report #El 4-286). 9. National Academies of Sciences, Engineeri ng, and Medicine. NCH RP 940, Solid-State Roadway Lighting Design G u ide, Vol . 1: Guidance. Washington, DC: National Cooperative H i g hway Research Program; 2020. DOI: 1 0.1 7226/25678. 1 0-15 Street Lig hting Cha pter 1 1 CO N T E N TS 1 1 .1 1 1 .2 Street Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -1 Wal kways and Bikeways in the 1 1 .3 Public Right of Way . . . . . . . . . . . . . . . . . . . . . . . 1 1 -1 Classifications a nd Definitions . . . . . . . . . . . . 1 1 -1 1 1 .4 1 1 .6 1 1 .5.3 Location Considerations . . . . . . . . . . . . 1 1 -6 1 1 .5.4 Safety and Security . . . . . . . . . . . . . . . . . 1 1 -6 Lighting Recom mendations . . . . . . . . . . . . . . . 1 1 -6 1 1 .6.1 1 1 .3 . 1 Street Classifications . . . . . . . . . . . . . . . 1 1 -2 1 1 .3.2 Pedestrian Activity C lassifications . . . 1 1 -2 1 1 .3.3 Pavement Classifications . . . . . . . . . . . 1 1 -2 1 1 .6.3 Lighting Criteria . . . . . . . . . . . . . . . . . . . . 1 1 -8 1 1 .3.4 Defi nitions . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -2 1 1 .6.4 An Alternative Method for 1 1 .6.2 Pedestrian Walkways and Bikeways Genera l Recom mendations . . . . . . . . . 1 1 -7 Design Considerations . . . . . . . . . . . . . . . . . . . . 1 1 -4 Determining Lighting Criteria . . . . . . 1 1 -9 1 1 .7 Design Ca lculations . . . . . . . . . . . . . . . . . . . . . . . 1 1 -9 1 1 .4.1 Appearance and Scale . . . . . . . . . . . . . . 1 1 -4 1 1 .4.2 Visual Task . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -4 1 1 .7.1 Recommended Calculation Methods . . 1 1 -9 1 1 .4.3 I ntegration with 1 1 .7.2 Recommended Luminance 1 1 .4.4 Vertical S u rface I l l u m ination . . . . . . . . 1 1 -5 Calcu lation Method for Streets . . . . . 1 1 -9 Non-lighting Elements . . . . . . . . . . . . . 1 1 -4 1 1 .4.5 1 1 .7.3 1 1 .4.6 1 1 .7.4 I m pact ofTrees on Lighting . . . . . . . . . 1 1 -5 1 1 .4.8 Spectral Considerations . . . . . . . . . . . . 1 1 -5 Design Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -5 1 1 .5.1 Curves and Steep G rades . . . . . . . . . . . 1 1 -5 1 1 .5.2 Trees Adjacent to Roadway . . . . . . . . . 1 1 -6 Recommended llluminance Calcu lation Method for Cul-de-Sacs . . 1 1 -9 I m pact of Head l i g hts . . . . . . . . . . . . . . . 1 1 -5 1 1 .4.7 Recommended l l l u mina nce Calcu lation Method for Walkways . . . 1 1 -9 Glare, Light Trespass, and Sky G low Issues . . . . . . . . . . . . . . . . 1 1 -5 1 1 .5 Streets - General Recommendations . . 1 1 -6 1 1 .8 Design Example - A Major (Arterial) Street . . 1 1 -9 Additional Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 -1 2 References for Chapter 1 1 . . . . . . . . . . . . . . . . . . . . . . 1 1 -1 3 Cha pter 1 1 Street Lig hting T he primary pu rpose of this cha pter is to serve as the basis for the design of continuous fixed l i g hting for streets, adjacent bi keways, and pedestrian ways with in the public right of way. This chapter deals entirely with l ighting design and does not g ive advice on construction. It is not intended for a pplication to existing l i g hting systems until such systems are completely redesigned. It has been prepared to advance the a rt, science, and practice of highway lighting in North America. The need for l i g hting of the street is typical ly defined 1 1 .2 Wal kways and Bikeways in the by the organization that has jurisdiction of the street. In Public Right of Way the U nited States, g uidance for warranting is provided This section d iscusses pedestrian wal kways and bike in the AASHTO Roadway Lighting Design Guide1 and paths within the public right of way. Activities such as i n the FHWA Handbook.2 In Canada, The TAC Guide for skati ng, skateboard ing, and rid ing of electric scooters the Design of Roadway Lighting includes g u ida nce for on bikeways and wal kways a re not covered in this warra nting.3 Once a decision has been made to provide document. l i g hting, this Recom mended Practice may be referred to for guidance in designing an a ppropriate roadway l ighting system . Included in this chapter a re coverage of street classifications, pavem ent classifications, and categories of potential pedestrian conflict. Where wa l kways and bike lanes are located adjacent to the street, spil lover l ig ht from the streetl ights may contribute to the i ll u m i nation of these areas. H owever, the lighting for the street may not produce the required l ig hting for pedestrians or cyclists, and additional l ig hting may be req u i red. 1 1 .1 Street Lighting Street lighting (see, for example, Figure 1 1 -1 ) refers to 1 1 .3 Classifications and Defi n itions l ig hting that is provided for major, collector, and local The terms used in this document m ig ht be used and roads, where pedestrians and cyclists a re genera l ly defined d ifferently by other documents, zoning bylaws, present during hours of darkness. The pu rpose of street b u i l d i n g codes, and agencies. For l i g hting design l ighting is defined in Chapter 1 0, Section 1 0.1 .1 . pu rposes, the classification for an area or street sho u l d Figure 1 1 -1 . Typical street lighting installations. (Left image courtesy o f Rick Kauffman; right image courtesy of Pa u l Lutkevich, Parsons Brinkerhoff) 1 1 -1 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities best fit the descriptions contai ned within this docu ment known, then "medium" activity should be assu med and not those of other sou rces. u n l ess land use and density meet the criteria for high or l ow. 1 1 .3.1 Street Classifications. The classification of • a street is typica lly defined by the j u risdiction that High pedestrian activity areas: More than 1 00 pedestrians d u ring the hig hest n i g htly average owns and operates the street system. The defi nitions one-hour provided here a re very general and intended to g ive a would i nclude downtown a reas with dense u rban general understanding. development (typically over 3,000 pedestrians per vo l u m e period. For exa m p l e, this square kilometer), areas a round major a renas. Major (arterial) street: That part of the roadway system that serves as the principal network for through­ • 1 1 and 99 pedestrians d u ring the highest nightly traffic flow. These routes connect areas of principal average one-hour vol ume period. traffic generation and im portant roadways entering and leavi ng the city. They a re sometimes subd ivided into Medium pedestrian activity areas: Between • Low pedestria n activity areas: 10 or fewer primary and secondary classifications; however, such ped estrians d u ring the hig hest n i g htly average d istinctions a re not necessary for the pu rpose street one-hour vol u m e period . In low activity a reas, l ighting. These routes primarily serve through-traffic it is recom mended that the j u risdiction defi ne and secondarily provide access to abutting property. whether sidewa l k l ighting is required, as l ighting will typically have lower value i n this application. Collector street: A road servicing traffic between major and local streets. These are streets used mainly for Pedestrian activity l evels d o not rema i n constant traffic movements within residentia l, commercial, and throughout the h o u rs of da rkness, and i n m ost i ndustrial areas. Collector streets may be used for truck insta nces, the n u m bers of pedestrians present i n each or bus movements and g ive direct service to abutting area w i l l be reduced in the late night and early morning properties. hours. Therefore, changes in pedestrian activities and Local street: Local streets are used primarily for direct access to residential, commercial, ind ustria l, or other abutting property. They make up a large percentage of the total street system but carry a small proportion of veh icular traffic. red u ctions in l i g hting levels can be considered. This can be accomplished by using adaptive l ig hting controls that allow lights to be d i m med. 1 1 .3.3 Pavement Classifications. The calcu lation of either pavement l u minance or Small Target Visibil ity 1 1 .3.2 Pedestrian Activity Classifications. Pedestrian areas a re genera l ly classified according to the level of pedestrian activity, sometimes cal led pedestrian volume, during hours of darkness. The logic for using pedestrian vol u me is based on the notion that the higher the vol u me of pedestrians on the sidewalk, the higher the probab i l ity that a pedestrian cou ld be on the street, and (STV) req u i res information a bout the directional surface reflectance characteristics of the pavement. Studies have shown that most common pavements can be g rou ped into a l i m ited n u m ber of standard road su rfaces having specific reflectance characteristics. (See Section 3.1 .5 for a description of the pavement classifications and Section 3.3.1 for the r-tables, which contain the data.) therefore, the g reater the need for h igher light levels. Other criteria in defi ning pedestrian activity a re the land 1 1 .3.4 Definitions. use and population density. Isolated traffic conflict area: Part of a road system where an i n c reased potential exists for collisions The choice of the pedestria n activity level is a n between vehicles, between vehicles and pedestrians engi neering judgement ca l l based on t h e estimated or cyclists, a nd/or between vehicles and fixed objects. n u m ber pedestrians typica l ly present in Exa mples include i ntersections, crosswal ks, and merge an a rea approximately 1 00 m long. If pedestrian vol ume is not 1 1 -2 areas. Hig hways a nd Interchanges Median: The portion of a divided roadway physically shared with other transportation modes withi n the road separating the traveled ways for traffic i n opposite rig ht of way.6 directions. Marked bike lane: A portion of a roadway that has been desig nated for preferential or exc l u sive use by bicycl ists by pavement markings and sometimes Pedestrian walkway or sidewalk: A public wa l k specifica l ly desig ned for pedestrian traffic within the road right of way; included are mu lti-use pathways (MU P). Figure 1 1 -3 (see Section 1 1 .4.3) shows their signs.4 typical l ocation. Cycle track: For the purposes of this docu ment, this area is physical ly separated from motor traffic and d istinct from the sidewa l k within road right of way.5 Bikeway: A generic term for any road, street, path, or way that i n some manner is specifically desig nated for Pole spacing definitions: The l i g hting industry has defined standard pole spaci ng layout desig nations. These standard pole-spacing layout designations are one-sided l i g hting, opposite lighting, staggered lighting, bicycle travel, regardless of whether such facil ities are a n d median lighting. Figure 1 1 -2 depicts typical pole desig nated for the exclusive use of bicycles or are to be spacing a rrangements. POLE I I I I I 0 £S s f I t S GEREO Figure 1 1 -2. Standard types of pole spacing. 1 1 -3 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities d riving task. When designing for areas of congestion or 1 1 .4 Design Considerations sig nificant interest, a l l owance needs to be made for the The aesthetics of myriad tasks that may be present. On a street, these could roadway l i g hting is most heavily influenced by l u m i naire include seeing pedestrians, d ropping off passengers, mounting height and layout. Lighting desig ners are viewing elements within the streetscape, dealing with 1 1 .4.1 Appearance and Scale. enco u raged to i nitiate their designs with the typical traffic congestion, reading signs, and other d riving tasks pole spacing arrangements and make adjustments as related to u rban areas. The recommendations i ncluded in this recommend practice a re for typical situations. If necessa ry. the designer notes unusual situations when considering For urban conditions, roadside development should be these items, reasonable eng ineering judgment should considered when selecti ng mounting heights in order be a ppl ied when applying the recommendations in this to m itigate light trespass onto adjacent properties and document. to m i n imize or e l i m i nate poles that a re out of scale with 1 1 .4.3 Integration with Non-lighting Elements. I n adjacent structures. u rban a reas, particularly in med i u m -to-high pedestrian 1 1 .4.2 Visual Task. An effort should be made to usage a reas, many elements m ig ht have to be i ntegrated completely understand the visual task in a g iven setting.7 a n d coordinated with the l i g hting system. Some of Too often, the designer thi nks only i n terms of the these elements a re noted in Figure 1 1 -3. The locations I I I I Sidewalk Auto/Bicycle Lane Med ian Auto/Bicycle Lane Sidewalk Public Right-of-Way Between Property Lines Sidewalk Median Strip Travel Lanes Street Light Poles Utility Junction Boxes/Panels Are Hydrants Garbage Contalners Landscaped Areas Trees Traffic Signs and Signals Outdoor Cafe Tables Loading Areas I Elevators Private Overhead Signs Private Awnings I Marquees Bus Shelters Left Tum Lane Plantings Traffic Signs and Signals StreetUght Poles Banner Poles Pedestrian Refuge Areas Trees Curbing Light Rail and Bus Platforms Normal Vehicular Traffic Bus Lanes Street Car or Light Rail Tracks Blcyde Lanes Curb Extensions 01)-Street Parking Traffic Calming Oevkes Figure 1 1 -3. Elements of the lighted right of way. 1 1 -4 Highways and I nterchanges of l ig ht poles need to be coordi nated with building and Design Guide for Canadian Roads11 for information on tree canopies, street furnitu re, trees, and la ndscaping, calcu lating sight stopping distances.) all of which can bl ock light and affect light levels. An assessment m ig ht be req u i red to define the i m pact 1 1 .4.7 Impact of Trees on Lighting. The type, size and that these objects w i l l have on the performance of the shape of mature trees should be taken into consideration lighting system. The designer and owner of the lighting as part of the lighting design so that roadway and system should look at the installation with all of the roadside functions and safety are not comprom ised. non-lighting elements and work to resolve conflicts. The l ocation, size and species of trees need to be considered along with the l u m i naire type, location, and 1 1 .4.4 Vertical Surface Illumination. The reflective mounting height. (See Section 3.1 .1 0 Impact of Trees properties of building faces and i l l u mination from the on Lighting and Section 5.2.6 Site Conditions for building windows can infl uence a d river's abil ity to see more information.) people on sidewa l ks in a negative or positive way. Care sho u l d be exercised in selection of the optical type and equ ipment p lacement to avoid creating a n obtrusive 1 1 .4.8 Spectral Considerations. The spectral content condition for the motorist or the abutting property of street l i g hting products is varied a nd, to a l i m ited users. Vertica l i l l u mination also plays a critical role in extent, control lable. Luminaires a re ava ilable with many prod ucing visibi l ity of pedestrians, cyclists, and objects different blends of spectra; from nearly monochromatic yel lows and reds to combinations of red, blue and g reen within street environments. that appear as white light to many observers. Designers 1 1 .4.5 Glare, Light Trespass, and Sky Glow Issues. may select the spectral content of l u m i naires to achieve Roadway lighting systems are u nder i ncreasing scrutiny effects of color in the envi ron ment of thei r projects. (See from various sectors of the public. While the public Chapter 1 0, Section 1 0.3.4 for spectral considerations is not usua l ly aware of specific design req u i rements for desig n.) of roadway lig hting systems, observations of g l a re, light trespass, and sky g l ow are widely perceived and The l u m inance levels in Table 1 1 -1 (in Section 1 1 .6.3) m ig ht be subject to criticism. Lighting designers should were developed for roadway l ocations in the d i rect l i ne become fam i l iar with these issues and be prepared to of sight of the observer and assume photopic vision. design a l i g hting system that meets the needs of the Therefore, mesopic factors a re not applicable. cl ient or owner, while also considering the possible effects of the lighting system on the environment. The reduction of spill l ig ht should, however, be weighed 1 1 .5 Design Issues against the need for proper surround lighting (defi ned Several major issues affect d river vision differently in in Chapter 1 0, Section 1 0.5.2.3), as these two elements rural compared to u rban a reas, and on l i m ited access vs. can conflict with each other. (For more information refer u n control led access roads. These include d ifferences i n to Chapter 4 Obtrusive Light.) speed and levels o f backg round l u m i na nce, frequency of intersections and driveways, presence of curb parking, 1 1 .4.6 I mpact of Headlig hts. H ea d l i g hts are the and most im portant, the n u m ber of pedestrians present. primary system i ntended to assist d rivers with seei ng The h igher levels of background lighting found in u rban objects on and along the road. The a b i l ity of head lights areas can aug ment roadway l u m i na nce and i l l u m inance to provide for detection of objects at vehicle speeds provided by l ig hting systems but can also produce glare above 50 km/h (30 m i/h) may not be adequate. It a n d distraction. Thus, off-road light sources can either is known that at hig her speeds the safe stoppi n g improve or impair a d river's vision. Other design issues sight d istance c a n exceed t h e visual detection distance are: provided by low-beam headlights.8•9•10 (See Chapter 3, Section 3.1 .8 for additional information.) (Refer to the 1 1 .5.1 Curves and Steep Grades. This topic is d iscussed AASHTO Roadside Design Guide4 or the TAC Geometric in Section 1 0.4.1 . 1 1 -5 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 1 1 .5.2 Trees Adjacent to Roadway. Where trees are 1 1 .6 Lighting Recommendations present, tree canopies can block l ight and making sidewalk levels difficult to achieve without additional 1 1 .6.1 Streets - General Recommendations. pedestrian scale lighting to specifically light the sidewal k. cha pter i n c ludes three different methods for use in This topic is covered in detail in Section 3.1 .10. This eva l uating different aspects of street l ighting desig n . These a r e l u m i nance, i l l u m inance, a n d s m a l l target 1 1 .5.3 Location Considerations. The designer should visibil ity (STV). (Refer to Chapter 3 for defi nitions and keep in m i nd the fol lowing: calculation methodolog ies.) • Pole locations should be compatible with d riveway entrances, pro perty l i nes, and windows of • Pole l ocations should be coord i nated with physical obstru ctions such as trees, d istribution • For this Recommended Practice, l u m ina nce is the transformers, util ity enclosures, and other util ity recommended design method for straight streets, infrastructure. Utility poles may be utilized where horizontal practica l and where the recommendations from recommended method for pedestrian crosswalks, and and vertical illuminance comprise the this Recommended Practice can be met, in order to horizontal illuminance is used for intersections, cul-de­ m i n i m ize pole cl utter and improve aesthetics. sacs, and surround areas. Clearance to overhead power l ines may limit pole and l u m inaire mounting heig hts. Pole heig hts should be chosen in proportion to roadway width (typical range is 25% to 1 00% of road width). • Su rround l i g hting as defined i n Section 1 0.5.2.3 sho u l d b e a p p lied i n areas outside t h e travel lanes. residential dwell ings. The horizontal i l l u m i nance method sha l l be used for cu rved roadway sections (less than a 600-meter rad i u s, where l u m i nance is not su itable due to l i mitations of the r-tables) and roads with steep and variable g rades (6% or g reater). Proximity to a i rport ru nways may l im it pole and l u m i naire mounting heig hts. Horizontal i l l u m inance sha l l also be used on streets with closely spaced i ntersections where the spacing 1 1 .5.4 Safety and Security. In some a reas it may between i ntersections is less than the l u minaire spacing, be desirable or necessary to provide safety a nd/or including the up- and downstream l u m i n a i res that security lighting. Safety lighting for the pu rposes of this are i n c l uded i n the l u m i nance calcu lation (refer to Recommended Practice refers to that which is req uired Chapter 3 for additional information on l u m i na nce for avoiding calamity and i nj u ry on streets, bi keways, calculations). This is 5 l u m inaire cycles, determined from and pedestrian walkways. the calculation cycle itself, plus 3 cycles downstream and 1 cycle u pstream . For example, if the spaci ng This document does not address lighting that may be (lum inaire cycle) is 30 m, then the d istance would be 30 required by local codes for safe eg ress from public m x 5 buildings and spaces. For these lighting req u i rements, would be used ifthe spacing between intersections was the reader should refer to the applicable building codes 1 50 m or less. = 1 50 m . In this case, a n i l l u m inance calculation or city ordinances. To determ ine what horizontal i l l u m i n a nce level Lighting wil l not ensure secu rity, but the presence of should be used for cu rved roads or tightly spaced l ig hting at the levels recommended in this docu ment intersections, the fol l owing equ ivalencies may be used: may provide a sense of secu rity for some people. (Refer 1 cd/m2 for 10 lux on Rl pavement; 1 cd/m2 for 15 lux also to Section 1 .1 Why Light?) Information on lighting on R2 or R3 pavement; and 1 cd/m2 for 1 3.3 lux on R4 for a reas where security is a particu la r concern may be pavement. It should be noted that these equivalencies found in /ES G- 1-16, Security Lighting for People, Property, are not conversion factors and only provide a rough and Critical lnfrastructure.12 approximation to use i n these more complex geometric 1 1 -6 areas. The recommended un iform ity ratios shall apply l u m i nance ratios) arrived at thro u g h practical experience for these roads, but not the veiling l u minance criteria. and ag reed upon by consensus of the IES Roadway Field validation of a lighting system's performance may va l ues a re not add ressed in this docu ment and should Lighting Committee. Variations and exceptions to the be done with l u m i na nce or i l l u m i nance. (See Section be evaluated with the necessary engi neeri ng study. For 5.6 exa mple, if it is decided to reduce the recommended - Field Verification for additional information.) va l ues by half (sometimes erroneously referred to as A lane adjacent to the road shoulder or curb ca n "ha lf-code" lighti ng), it can not be assumed the benefit often be wider than the sta ndard lane width of 3.6 is a lso half. If the u niformity val ues or glare values are m (approximately 12 ft). When u ndertaking l ig hting twice the recom mended va l ues, visibil ity m i g ht be calcu lations for lanes wider than standard widths, the severely hampered instead of sim ply being half of what maxi m u m lane width from the road centerline or edge it would be. Red uctions should only be considered in of adjacent lane shall be 3.6 m. This is so the assumed the context of adaptive l i g hting, as described in Section motor vehicle location is in the actual travel portion of 5.2.8. the street. Other Where pa rt-time parking la nes exist or are proposed, l ig hting sha l l be calcu lated as if they were fu l l -time consid e rat i o n s when applying these recom mendations include: • When a specifying authority selects a specific B-U-G general-purpose la nes. Full time on-street angled or rating (see Section 2.6.3) for a street's l u m inaires, paral lel parking, where there is no chance the parking this s ha l l not serve to com prom ise the design lane w i l l be used as a travel lane, shall not be included criteria as determined by the Street Classification in the l i g hting calcu lations for the lane(s); instead, the and the Pedestria n Classification (see Sections recommended surrou nd ratio (refer to Section 1 0.5.2) 1 1 .3.1 and 1 1 .3.2, respectively). However, where shall be applied outside the travel lane. the Glare part of the BUG rating and the vei l i n g luminance (Lv) calcu lations conflict, t h e Lv s h a l l take The recom mended surround ratio shall be used to l ig ht priority. areas outside the travel lanes. Where ma rked bike lanes or cycle tracks a re encou ntered, the su rround ratio sha l l • Zones may have an Classification. • Ambient contributions from lighting off the street that is not part of the street and walkway l ighting used to evaluate d isability glare as experienced by the system shall not be considered in the l ighting d river. Stray light within the eye, produced by l ig ht calculations. sou rces in the field of view, effectively superim poses a "veil" of l u m i nance on the retina. This decreases the Lighting influence i n t h e selection o f t h e proper Street b e a pplied t o t h e i ll u m i nation o f these areas. In street l i g hting, vei l i n g l u m inance, Lv, is the metric Enviro n m enta l • Off-road l i g hti ng i nsta l lations shall take i nto apparent contrast of objects against their background consideration a ny adjacent streets so as not to and can sometimes cause discomfort glare. In Table create a ny safety adaptation issues for d rivers. 1 1 -1 in Section 1 1 .6.3, the criterion for l i m iting glare is expressed as the Veiling Lum inance Ratio, which 1 1 .6.2 Pedestrian Walkways and Bikeways - General is the vei l i n g l u m ina nce maxim u m d ivided by the Recommendations. average l u minance of the road su rface. In this way, pedestrian wal kways and The design criteria for lighting bikeways are based on l u m i na i re "brig htness" is considered i n the context horizontal and vertical illuminance. The specification of of the "brig htness" of the road surface as seen by the minimum maintained horizontal illuminance will serve d river. to provide visibility of bikeway or walkway surfaces and their defined boundaries for their respective users. This The l i g hting recom mendations given in this chapter are can be accomplished in several ways. If safety is the only m i n i m u m val ues (or maximum for u niformity and vei l i ng consideration, low lumen output luminaires having no 1 1 -7 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities upward light and installed at lower mounting heights withi n the road right of way but outside of the surround should work adequately for bikeways and walkways. The area, wal kway levels sha l l apply (see Table 1 1 -2). l ighting should be such that the source is close to the edge or over the bikeway or walkway, producing a positive contrast between persons and the background area. Definitions for pedestrian activity a reas can be found in Chapter 1 1 , Section 1 1 .3.1 . The desig ner may consider 1 1 .6.3 Lighting Criteria. Luminance is the design criterion for street lighting, except where defined in Section 1 1 .7.1 . The recommended values are defined in Table 1 1 -1 . It Table 1 1 -2. Recommended Design Criteria for Walkways Within Road Right of Way is recommended that illuminance calculations also be performed for the resultant design in order to provide values that can more easily be used for field validation of Condition Eavg1 lux (fc) fv,avg lux (fc) favg/fm1n High 1 0 (0.9) 5 (0.5) 5.0 5 (0.5) 2 (0.2) 5.0 2 (0.2) 1 (0.1) 1 0.0 . pedestrian the performance of the installed lighting system. activity Medium For lighting the wal kway (sidewal k), horizontal and vertical pedestrian illuminance is the design criterion. The recommended activity values are defined in Tables 1 1 -1 and 1 1 -2. Low pedestrian The lighting design criteria provided in Tables 1 1 -1 a n d 1 1 -2 do not consider areas with increased crime a n d vandalism. IES G-1-16, Security Lighting for People, Property, and Critical Infrastructure offers gu idance for such areas.12 activity Table Notes: fa vg: Minimum maintained average horizontal i l l u m ina nce at pavement Em ;n: Minimum horizontal i l l u m i nance at pavement Where a bikeway is adjacent to the roadway (withi n the fv,a vg : Average vertical illu mina nce at l .5m above the pavement surround a rea) the lighting of the bikeway sha l l meet in both directions and parallel to the main pedestrian flow the surround ratio req u i rements. Where the bikeway is • Horizontal only Table 1 1 -1 . Lighting Design Criteria for Streets Street Classification Major Collector Local Pedestrian Activity Classification * Average Luminance Lavg (cd/m 2) Maximum Maximum Veiling U niformity Ratio Luminance Ratio Lavg/Lmin Lmax/Lmin Lv,max/Lavg High 1 .2 3.0 5.0 0.3 Medium 0.9 3.0 5.0 0.3 Low 0.6 3.5 6.0 0.3 High 0.8 3.0 5.0 0.4 Medium 0.6 3.5 6.0 0.4 Low 0.4 4.0 8.0 0.4 High 0.6 6.0 1 0.0 0.4 Med i u m 0.5 6.0 1 0.0 0.4 Low 0.3 6.0 1 0.0 0.4 Table Notes: · Pedestrian Activity Classifications are defined in Section 1 1 .3.1 . Lavg: Maintained average pavement l u m ina nce L m;n: M i n i m u m pavement l u m inance Lv, max: Maxi m u m ve iling l u m i nance 1 1 -8 Average Uniformity Ratio Highways and I nterchanges reflected l ight from the sidewa l k su rface, which can be and su rround l i g hting are provided in Chapter 1 0. a sign ificant contributor. Semi-cylind rical i l l u minance Calcu lation g rid placement and point spacing a re may a lso be considered as a design metric. Additional discussed in several subsections within Section 3.2 .3. information on this metric can be found i n C/f 7 75:2070, Lighting of Roads for Motor and Pedestrian Traffic.1 3 The 1 1 .7.3 References for Chapter 1 1 , found at the end of this Method for Walkways. Lighting c a l c u lations for chapter, g ive m ore backg round information on the sidewa l ks s h o u l d horizonta l design criteria.13•14•15•16 i l l u minance. The same lighting system w i l l typical ly Recommended llluminance include Ca lculation and vertica l provide lighting for both sidewalk and street. Where Surround Ratio (SR) as defined in Section 1 0.5.2.3 h i g h pedestrian activity levels are present, additional should be appl ied. pedestrian scale l ighting may be needed to achieve recom mended l ighting levels on the sidewa l ks. 1 1 .6.4 An Alternative Method for Determining Lighting Criteria. for It is im portant to note that when u ndertaking l ig hting determ ination of appropriate roadway l ig hting design calculations on roadways with sidewalks, the calculations criteria, based on the analysis of crashes and lighting for sidewa l ks sha l l be performed using a separate performa nce, is described in Annex K An alternative process Alternative calculation g rid. The l u m i nance on the street sho u ld Lighting Criteria Selection Methodology. A series of be calculated first, a n d once a ppropriate roadway - conditions are described and associated lighting design design l u m i nance req u i rements have been achieved, criteria developed to provide a n a pproach for l ig ht level the sidewa l k calcu lations should be made to confirm selection, including adjusta bility of the light level based that the recommended maintained i l l u m i nance levels on changing needs of the d riving environment. and un iform ity ratios for the sidewal k have also been ach ieved. In some cases, meeting the i l l u minance levels and uniformity on the sidewa l k may req u i re a higher 1 1 .7 Design Calcu lations l ighting level on the street, or additional pedestrian sca l e l i g hting may be required to achieve the sidewal k 1 1 .7.1 Recommended Calculation Methods. Th ree l ighting criteria. methods a re typica l l y ava ilable in computer software for those performing roadway l ig hting calcu lations. Calcu lation g rid placement and point spacing a re They are the l u minance, i l l u m i nance, and STV design discussed in Section 3.2.3.2. methods, as defined in Chapter 3 - Calculations. Most design software wil l make calculations and provide 1 1 .7.4 results using a l l three methods. Method for Cul-de-Sacs Lig hting Recommended ca l c u lations lllumina nce for c u l -de-sacs Ca lculation should be method of undertaken using a maintained horizontal illu minance calculation is luminance. For cul-de-sacs, the recommended calculation. The a rea of a cul-de-sac begins at the end of method of calculation is illuminance. The designer should the c u rb return radi us. Where roads leading into the cu I­ For street lighting, the recommended make design decisions and adjust variables to meet the de-sac meet the same road length criteria as defined luminance requirements for the street, and the illuminance for closely spaced intersections (see Section 1 1 .6.1), criteria for the sidewalk and cul-de-sac. i l l u m inance calcu lations shall be used. II l u m i nance levels can a lso be determ i ned for comparing l l l u m in ance criteria for with i n the c u l -de-sac a re calculated levels with field measurements. (For more provided in Chapter 12. information, refer to Chapter 5.6.2 - Field Verification.) 1 1 .7.2 Recom mended Lumina nce Calculation Method for Streets. The calculations for the street 1 1 .8 Design Example - A Major (Arterial) Street The fol lowi ng step-by-step descriptions i l l ustrate 1 1 -9 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities the process that a l i g hting designer wou l d fol low First, the roadway lighting levels are calculated; once to determ ine the l ig hting layout for this street and they a re achieved, the sidewa l k criteria are checked. wal kway lighting exa mple. (Refer to Chapter 5 The This w i l l req uire separate calcu lations. Both sidewal k Planning and Design Process for more i nformation.) a n d roadway l ighting levels and uniformity shall be Figure 1 1 -5 shows a sample l i g hting-ca l culation output ach ieved. - for this exam ple. Step 5: Determine pole layout Step 1: Determine roadway features Confirm pole arrangement (e.g., staggered, opposite, The roadway is a fou r-lane major road with sidewal ks one sided). In this case, staggered was deemed the and med i u m pedestrian activity. best option. Poles for this road should be placed first at i ntersections and then between the intersections Step 2: Select lighting criteria using the optimal spacing. The pole spacing may need From Table 1 1 -1 , the recom mended val ues for a major to be adjusted to suit the actual d istance between street with medium pedestrian activity a re: • intersections and any driveways or other obstacles. Street 0 0 The calculations are then performed again to reflect Average luminance (cd/m2): 0.9 this new pole spaci ng, making sure the criteria are sti l l Average-to-minimum l u m ina nce u niformity ach ieved. I t i s i mportant to note that close coordination needs to take place with the road desig ner to achieve ratio: 3:1 0 Maxi m u m-to-mi n i m u m l u m ina nce u niformity u nderground utilities, overhead power l ines, cu lverts, ratio: 5:1 0 • proper pole layout; smaller isolated obstructions l i ke Maxi m u m veiling l u m inance ratio: 0.3:1 Sidewalk signs, or reta i n i n g structures w i l l req u i re i nd ividual adjustments of poles. The g oa l is to provide a un iform pole spacing throug hout the length of roadway. It is 0 Average horizontal ill u m i na nce: 5 lux recommended that the actual maxi mum pole spacing 0 Average vertical i ll u m i na nce: 2 l u x calculation used in the design be shown on the design 0 Average-to-m i n i m u m horizontal i l l u m inance d rawings. u niformity ratio: 5:1 Note: If sidewalk levels can not be achieved, then taller Step 3: Select equipment poles and l u m i naires with higher lumen output may be For this roadway, the owner has requested that l ig ht needed, or additional luminaires may be required on trespass and g la re be m i n i m ized, so the l u m inaire w i l l the front or back of the poles to provide optimal l ig hting have B U G ratings w i t h l o w Backlig ht, Uplig ht, and Glare of the sidewalk. components. The desig ner sha l l confirm l u minaires and poles, as often the ju risdiction who operates the road will have standard poles and l u minaires. In this case, LED l u minaires and 1 1 .0-m high poles were selected. Step 4: Calculate Using computer design software, layouts are calcu lated using the process described in Chapter 5, Section 5.4. The combi nation of pole height, spacing, l u m i naire d istribution, and l u men output that meets or exceeds the m i n i m u m recommended values should be compared from an economic sta ndpoint to determine the most cost-effective alternative that meets the owner's needs. 1 1 -1 0 .,, IC. c .. ID ... ... 0 r ;:o co S:: > -o rc :;: z )> � m il 0 rm VI Ill 3 "'C iD .. 0 Ill c. :e Ill �il '< ,., Ill ;:; c ill ... (\ ,,,, % < "' ID :e Ill � Cl .- "' c: 0 m � �N 6� ;:::!; >0 ID ID I c :;: < m ;= z G') rc s:: z )> z � C'l m � 0 '? :::; ,. , ' \ x \o 'l O\! x � O '1 \x o 1 x\o 'I " /Y x .. 0 \\ \ \' \X 0 \ r- < ;:o ��� - o z z ::::?: - � " m � � G') -< )> C'l ;!! 0 � .- m i>" o \t\ "!\ c -I iJ c -I ;;o m en c i>" � .! '!': � �� <l Z m9 � � o� c: z ;;; � z z � r -I en ;;; E ;;; ;; � it � zo .:... � � 0 r­ m � � % � �Gl - en , _ r- 0 C m � ::::?: z )> r )> z ;:<; 0 :I: m o ;:o §z > r- c: z S! 2i it -< "' zO� .:... 0 c -! "ll c -! ;u m (/l c �il L C! m - (Jl i (\\q,,'"-.=:'C. § c: i!; > r- " <SJ "> �\\ '3 �i� ., il� � 0 ,. � � � � " f.I 0� E;: j: z � Cll z �.<SJ �\ � � C?z.lf. r % � �\ "(>�t>"Y­ e, C5 )> .c: :;: § -< m ::c 0 ;:o .> " o· ?. "' ... .. ... Ill :I c. "' ii � � Z C'l )> r c s:: z )> � :::c: ..c· ::r ::E 0 j\J .... .... I .... .... �\�., " \ :'} Ill '< "' Ill ::I c.. ::I ..+ ID ..... n ::r Ill ::I IC ID "' ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities A D D I T I O N A L R E AD I N G Note: This section is not part o fANSI/JES RP-8-27. It is included for informational purposes only. American Association of State Hig hway and Tra nsportation Officials. AASHTO GL-6-2005, Roadway Lighting Design G uide, 61h ed. Washington, DC: AASHTO; 2005. I l l u m i nating Engi neeri ng Society. ANSI/I ES LP-4-20, Lighting Practice: Electric Light Sou rces - Properties, Selection, and Specification. New York: I ES; 2020. I nternational Commission on I l l u m ination. CIE 1 91 :201 0, Recommended System for Mesopic Photometry Based on Visual Performance. Vienna: CIE; 201 0. 1 1 -1 2 Hig hways a nd Interchanges R E F E R E N C E S FOR CHAPTER 1 1 1. American Association of State a nd Hig hway Tra nsportation Officials. Roadway Lighting Design G u ide, 7th ed. Washington, DC: Federa l H i g hway Ad min istration; 201 8. 2. Federa l H i ghway Ad min istration. FHWA Lighting Hand book. Washington, DC: FHWA; 201 2. (FHWA-SA-1 1 -22). 3. Transportation Association of Canada. Guide for the Design of Roadway Lighting. Ottawa: TAC; 2006. (PTM­ LIGHTI NG06). 4. Manual of U niform Traffic Control Devices (MUTCD) 2009 Edition with Revision N u m bers 1 and 2 i ncorporated, dated, May 201 2 5. Nationa l Association o f City Transportation Officials - U rban Bikeway Design G u ide 6. American Association of State and Hig hway Transportation Officials. Roadside Design G u ide, 4th ed. Washington, DC: Federal H i g hway Ad ministration; 201 2. 7. I nternational Commission on I l l u m i nation (CIE). CIE 1 00-1 992, Fundamenta ls of the Visual Task of N ig ht Driving. Vienna: CIE; 1 992. 8. J M U Office o f P u b l i c Safety. Detection and safe stopping d istances. Ha rrisonburg, Virg.: Ja mes Madison U niv.; Oct 2009. 9. Roper VJ, Howard, EA. Seeing with motor car headlamps. Tra ns l ll u m i n Eng ineering Soc. 1 938;33(5):417-38. 1 0. Johansson G, Rumar K. Visible distances and safe approach speeds for night d riving. Ergonomics. 1 968;1 1 (3):275282. 1 1 . Transportation Association of Canada. Geometric Design G u ide for Canadian Roads. Ottawa: TAC; 201 7. 1 2. I l lu m i nating Engi neering Society. IES G-1 -1 6, Security Lightin g for People, Property, and Critical Infrastructure. New York: IES; 201 6. 1 3 . I nternational Commission on I l l u m i nation (CIE). CIE 1 1 5:201 0, Lighting of Roads for Motor and Pedestrian Traffic. Vienna: CIE; 201 0. 14. Federal H i ghway Ad min istration. FHWA TS-90-028, The Relationship of Fixed and Vehicular Lighting to Accidents. Washington, DC: FHWA; January 1 990. 1 5. I nternational Com m ission on I l l u m i nation (CIE). CIE 93-1 992, Road Lighting as a n Accident Countermeasure. Vienna: CIE; 1 992. 1 6. Richards SH. The Effects of Reducing Conti nuous Roadway Lighting to Conserve Energy: A Case Study. 1 5th Annual SAFE Symposiu m . College Station, Tex.: Texas Tra nsportation Institute; December 1 977. 1 1 -1 3 I nte rsections, Ro u nda bouts, a n d Crosswa l ks Chapte r 1 2 CO N T E N TS 1 2.1 1 2.2 1 2.3 1 2.4 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2-1 1 2.4.4 Lighting Recom mendations for Rou ndabouts . . . . . . . . . . . . . . . . . . . . . 1 2- 1 3 1 2. 1 . 1 Land Use Definitions . . . . . . . . . . . . . . . 1 2- 1 1 2. 1 .2 I ntersection Defi n itions . . . . . . . . . . . . 1 2- 1 1 2. 1 .3 Pedestrian Activity Defi nitions . . . . . . 1 2-2 1 2.5 Crosswalks at I ntersections . . . . . . . . . . . . . . 1 2-1 7 1 2. 1 .4 Lighting Defi nitions . . . . . . . . . . . . . . . . 1 2-2 1 2.6 Midblock Crosswalks . . . . . . . . . . . . . . . . . . . . 1 2-1 8 1 2.4.5 Roundabout Calculation Exa mple . . . 1 2- 1 4 Design Considerations . . . . . . . . . . . . . . . . . . . . 1 2-3 1 2.6. 1 Su pportive Research . . . . . . . . . . . . . . 1 2- 1 8 1 2.2.1 Safety. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2-3 1 2.6.2 Design Considerations for 1 2.2.2 Site Conditions . . . . . . . . . . . . . . . . . . . . . 1 2-3 1 2.2.3 Design Criteria . . . . . . . . . . . . . . . . . . . . . 1 2-3 1 2.6.3 1 2.2.4 Identification of Design Elements . . . 1 2-3 1 2.6.4 1 2.2.5 Spectral Considerations . . . . . . . . . . . . 1 2-3 M id block Crosswalks . . . . . . . . . . . . . . 1 2- 1 9 Mid block Crosswalk Design Issues . 1 2-20 Lig hting Recommendations for M id block Crosswalks . . . . . . . . . . . . . . 1 2-20 I ntersections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2-3 1 2.6.5 1 2.3.1 I ntersection Design Issues . . . . . . . . . . 1 2-4 1 2.6.6 1 2.3.2 I ntersection Lighting Requirements . . 1 2-5 Design Calcu lations . . . . . . . . . . . . . . . 1 2-20 Mid block Crosswalk Design Exa mple . . . . . . . . . . . . . . . . . . . 1 2-21 Roundabouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-8 1 2.4.1 Key Di mensions and Categories . . . . 1 2-9 1 2.4.2 Rou ndabout Traffic Operations . . . . 1 2- 1 0 1 2.4.3 Design Considerations for Roundabouts . . . . . . . . . . . . . . . . . . . . . 1 2- 1 2 References for Chapter 12 . . . . . . . . . . . . . . . . . . . . . 1 2-23 I nte rsections, Ro u nda bouts a n d Crosswa l ks T Chapte r 1 2 he pu rpose of this cha pter is to provide information regarding lighting for street intersections, rou nda bouts, and crosswalks. In each of these situations, there is an i ncreased potential for vehicle conflict a nd/or vehicle­ pedestrian conflict. A d river's attention needs to be focused on m u ltiple parts of the visual scene. Both fovea l vision and peripheral vision a re critical t o safe approach and navigation o f these conditions. Fol l owing Section 12.1 Definitions and Section 12.2 12.1 .2 I ntersection Definitions. Design Considerations a re sections on trad itional Intersection: The general a rea where two or more i ntersections (Section 1 2 .3), roundabouts (Section roads cross at the same level. Also cal led a grade 12.4), and crosswa l ks (Sections 12.5 and 1 2.6). intersection. 1 2 .1 Defi nitions may be classified as one of the following based on the Intersection classifications: Each i ntersecting street average daily traffic (ADT): 12.1 .1 Land Use Definitions. Land use classifications of urban and rural are used to assist in determining the recommended i l l u m ina nce levels for intersection • Major (M) street: Over 3,500 vehicles ADT • Collector (C) street: 1 ,500 to 3,500 vehicles ADT • Local (L) street: 1 00 to 1 ,500 vehicles ADT l i g hti ng. The terms rural, suburban, and urban a re defined as follows: These classifications result in six types of intersections: M/M, M/C, M/L, CIC, C/L, and L/L. (Note: These street Urban: U rban areas a re within the bou ndaries of a classifications do not apply to the roadway classifications city, municipal ity, town, or village where there is active of Tables 1 0-2, and 1 1 -1 , but they may be used in pedestrian traffic and commercial development. The dete r m i n i n g intersection l i g hting levels from Table classification of urban can be qu ite subjective. It typica l l y 12-1 , in Section 1 2.3.2.) incl udes a reasonable level o f nighttime activity, the presence of sidewalks and streets with curb and g utter, Isolated intersection: A lig hted a rea in which two or and a mix of com mercia l, ind ustrial and residential more non-contin uously lighted roads join or cross at deve l op ment. the same level. This a rea includes the road and roadside Residenti a l deve lopment i n cl u des single-fa m i ly and m u ltifamily dwel l ings. Commercia l fac i l ities for traffic movement in that area. A special development incl udes retai l and non-reta il businesses type is the channelized i ntersection, i n which traffic and shops where pedestrians can travel between local is d irected into definite paths by islands with raised destinations via sidewalks. curbing. Rural: Rural a reas a re outside of urban a reas, with Crosswalk: Any portion of a roadway at a n i ntersection l ittle or no commercial development and little or no or e l sewhere disti nctly ind icated as a pedestrian crossing nig httime pedestrian traffic. Typical ly, rural roads have by l ines on the surface, which may be supplemented by gravel shoulders with open ditches and no sidewalks. contrasting pavement textu re, style, or color. Rural a reas include fa r m l a nd, provincia l parks, and g reenfield a reas with little or no commercial or residential development. Additional considerations: • The vol u m e of traffic at the intersection of one l ocal street with a nother is typica l ly q u ite low. In contrast, Suburban: Suburban a reas a re transition a reas between vol umes at i ntersections of local streets with major rura l and u rban areas. streets are pri marily those of the major street. If 12-1 ANSl/IES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities the i ntersecting street is of collector or major type, activities, such as regional shopping centers, wil l be the total volume is substantially increased due to used by thousands of vehicles per day and should the traffic on the cross street. Also, denser land be i l l u m i nated to levels similar to those of major uses, such as commercial or ind ustria l, generate streets. higher vol u mes for a l l types of streets. Figure 1 2-1 i l l u strates the vehicle conflict points in a n At the i ntersection of two streets, both carrying intersection. T h e l i kel ihood o f pedestrian conflict is two-way traffic and having no restriction on turning also a n im portant consideration. • movements and no signal control, there a re a total of Driveways onto streets are m iniature intersections 32 veh icle-to-vehicle conflict points (see Figure 12-1 ). and should be classified accord i n g l y. Those serving An equal n u m ber of pedestrian conflict points exist; a single-fa m i ly home typical ly generate a bout 1 0 i.e., there a re four crossing veh icular movements for trips per day-i.e., five vehicles i n and five vehicles each crosswal k (right turns and left turns from the cross out-and do not require a ny special lighting. At street, and straight-ahead from both d i rections on the the other extreme, d riveways serving hig h-volume street crossed by the wal k). 32 CONFLICT PTS Several studies have identified that the primary benefits o B Diverge • 8 Merge • 1 8 C ross prod u ced by l i g hting of intersections a l o n g major streets is the reduction in nig httime pedestrian, bicycle, a n d fixed-object accidents.1• 2 1 2 .1 .3 Pedestrian Activity Definitions. The potential for and prevention of pedestrian conflicts is a n i mportant consideration and a primary reason for l ig hting roadways and i ntersections. The criteria used in selecting an appropriate l i g hting level are based on the total num ber of pedestrians in a l l the crosswal ks at the intersection over a g iven one-hour period . Pedestrian conflict potential is based on pedestrian activity level, as defined i n Section 1 1 .3.2. 12.1 .4 Lighting Definitions. Full intersection lighting: Lighting covering the fu n ctional area of a n i ntersection in a un iform manner over the traveled portion of the roadway. Partial intersection lighting: Lig hting of key decision areas, potential conflict poi nts, a nd/or hazards in and on the approach to a n intersection. Partial i ntersection l ig hting may also g u ide a driver from one key point to the next, and (if sufficient l u m inaires are used) place the road user on a safe heading after leavi ng a n i l l u m inated area. Figure 1 2-1 . Vehicle conflict points at four-way Delineation (beacon) lighting: Lighting that ma rks intersections. (Sou rce: Traffic Engi neering, McGraw- H i l l an i ntersection location for approaching traffic, l i g hts Book Compa ny, I nc. 1 955.) veh icles on a cross street, or lig hts a median crossing. 1 2-2 I ntersections, Roundabouts and Crosswalks 1 2 .2 Design Considerations Many of the design considerations for intersections • Full, partial, or del ineation l ig hting • Consideration of any local pol icies and ordinances are typical for a l l roadway-related l i g hting designs. Intersections are i l l u m inated to improve visibil ity for 12.2.4 Identification of Design Elements. Design roadway users. Fundam ental des i g n consid erations considerations a l so include va ria ble design elements include safety, site cond itions, design criteria, and that need to be defined for a lighting desig n. These identification of design elements, each of which is incl ude pole p lacement options, light sou rce type, discussed below. mounting heig ht, pole arm l ength, pole offset, l u m i naire type and wattage, l u m i naire l i g ht output, and l ig ht 1 2 .2.1 Safety. The primary objective of roadway distribution. Typica l ly, few pole placement options l ig hting is to enhance road user safety by provid ing are ava i lable at intersections, due to the presence of improved nighttim e visibi lity of roadway conditions other elements. These restrictions force designers to be and potential hazards. Light poles and other physical creative when l i g hting intersections. Luminaire wattage devices (such as power transformers and electrica l a n d mou nting height may need to vary from those cabinets) present potential hazards to errant vehicles on the approach roads to meet the req u i red levels of and sho u ld be insta l led in safe locations. The designer i l l u m ination and uniformity ratios for the intersection. of the roadway l ig hting system should also consider the locations of luminaires, poles, and other electrical 12.2.5 Spectral Considerations. The spectral content devices with respect to the a b i l ity of maintena nce of roadway l ig hting products is varied a nd, to a l i mited crews to conduct activities in a safe, economical, and extent, control lable. Lum i na i res a re ava ilable with many effective manner. Clea r zones and req u i rements for pole different blends of spectra; from nearly monochromatic locations as described in AASHTO and other regulatory­ yel lows and reds to combinations of red, blue and g reen agency documents should be considered. that appear as white l ight to many observers. Designers may select the spectral content of l u minaires to achieve Although roadway l ighting may i m prove the visibility effects of color i n the environment of their projects. (See of objects at night, l ighting also has the potential to Chapter 1 0, Section 1 0.3.4 for spectral considerations create conditions where a d river's vision has adapt to for desi g n .) darkness or lower levels of l u minance when leaving the l i ghted a rea. In addition, lighting has the potential to The i l l u minance levels recommended in this chapter create situations where glare may red uce or disable an assume photopic vision. Therefore, mesopic factors are ind ivid u a l from performing the visua l tasks associated not a pplicable. with use of the roadway. For these reasons, specific l ighting design criteria have been developed for various kinds of intersections. 1 2 .3 I ntersections Intersections may have u n restricted traffic flow on both 12.2.2 Site Conditions. I nvestigation of site conditions roadways, restriction by means of stop signs on one or should be considered to establish the context i n which both of the roadways, control by traffic signa ls, control the lighting design will be completed. The conditions by pol ice officers, or control by other means. Some are to note include surrou n d i n g land uses, traffic a n d compl icated by the presence of pedestrians as wel l as pedestrian activity levels, intersection and roadway veh icular traffic. The l ig hting sol ution is fu ndamenta l ly geometry and classification, and potential hazards. the same regardless of the compl ications identified: it is desirable to provide adeq uate visib i l ity of vehicles and 12.2.3 Design Criteria. Design criteria should be esta blished prior to beg i n n i n g the l i g hting desi g n . pedestrians i n the a rea of the i ntersecting roads and on the pedestrian crosswa l ks. These criteria include: • Light level and u niformity req u i rements The lighting design parameters for grade intersections are • Pavement classification type dependent on whether continuous or non-continuous 12-3 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities lighting exists. If the grade intersection is in an area of • Collision data and investigations. Wa rranting continuous lighting, then the lighting design levels and decisions a re based in part on collision data. It u niformity should fol l ow the recommendations given is critica l that specific col l ision data related to in Section 12.3.2.1 . If the g rade intersection is in an i l l u m i nation a rea of non-continuous lighting, then the lighting design appropriate authorities. systems be m a i ntai ned by the principles and procedures should follow Section 12.3.2.2. 1 2.3.1 .2 Coordination With Other Elements. Lighting 1 2.3.1 Intersection Design Issues. eq u i pment at i ntersections will need to be coordinated 1 2.3.1 .1 Typical Roadway Issues. An effective lighting system design for intersections needs to deal with several issues if it is to be successfu l ly i m plemented and operated. Consideration of each of the topics below, as applicable, will serve as a checkl ist for ensuring a good design. • Safety. I m p rove nighttime visi bil ity of roadway The elements below may req u i re some compromises in the fi nal placement of light poles and equi pment: the roadway right of way (ROW). • Driveways and property access l ocations Cost. Determine available capita l (construction) • Sidewalks and sidewa l k ra m ps, bike paths, street operati ng costs; m i n i m ize fu rniture, and other physical features of the roadway l i g hting infrastructure as much as possible to provide the necessary a m o u nt of l ig ht for roadway user safety. • genera l ly mou nted on traffic signal poles to reduce clutter and i nstallation costs. Roadway geometrics and available property costs and • present. At signal ized intersections, the l u m i naires are • conditions and identify any potential hazards within • with the other infrastructure elements that may be • Signage and traffic signal equ ipment • U nderground and overhead utilities Aesthetics. This is influenced by the pole height and location. The layout of poles can be typical; 1 2.3.1 .3 Clear Zone. General ly, traffic signal and light alternatively, where high pedestrian volumes are poles at intersections are afforded special consideration encou ntered, (e.g., in u rba n downtown areas), for shorter offsets from the travelled roadway due to l ig hting using shorter, pedestrian-sca l e poles m ig ht physica l constraints such as signal arm lengths, visibil ity be more aesthetica l ly pleasing. of traffic signal heads, and access to pedestrian push Environmental considerations. Tree clearing buttons. Island poles are generally of more concern due and the use of tal ler poles with a larger setback to even shorter offsets from the travelled portions of the from the roadway will facilitate a wider i ll u m i nated roadway. These poles are involved i n freq uent vehicle­ area. pole col l isions. However, l im its should be placed on these procedures in order to m i n i m ize the effects of • obtrusive lig htin g, i n c l u d i ng l i g ht trespass, sky Pol e locations sha l l not compromise the safety of d rivers g low, and offsite glare. Luminaires with a low-G a n d pedestrians due to errant vehicles. G iven that BUG rating should be considered to reduce veil i ng breakaway poles a re not used on signal poles for l u m i na nce. reasons of safety, poles should be l ocated as far back Site conditions. This incl udes the presence of as possible, though frequently not meeting clear zone trees and bushes as obstructions. Lighting should req u i rements. take precedence. A designer should be aware of possible shadowing, as it can negatively affect 1 2 .3.1 .4 Crosswa l ks. While h orizontal in m ost cases the for an visi bil ity. Areas in c lose proxim ity to bodies of reco m m ended salt water may resu lt in roadway lighting system intersection can b e achieved by using combination i l l u m i n a n ce components experiencing corrosion. sig nal and l u m i naire poles, a key consideration is that Concrete, a l u m i n u m, or galva nized steel poles may this arra ngement will not typical ly provide optimal be used as an effective way to reduce problems. vertical i l l uminance within the crosswa l k area. 1 2-4 chem ica l I ntersections, Roundabouts and Crosswalks For i ntersections with high pedestrian conflict a nd/or ful l l ig hting on the approach roads, improvi ng vertical i l l u m i nation in the crosswalk should be considered. This can be accom pl ished by insta l l i ng separate light poles i n advance of the stop bars. This w i l l improve the visibility of pedestrians i n the crosswa l k for motorists approaching the intersection. 12.3.1 .5 Obtrusive Light. e n h a nces safety, Lighting at i ntersections especially where considera b l e pedestrian traffic exists. It a l s o serves t o i l l u m inate conflict poi nts (see Figure 12.1 in Section 12.1 .2), to minimize the potential for vehicle-vehicle collisions. I- -L!CENO CAlCULATIOH ARCA If obtrusive l ig ht (see Chapter 4) is of concern, steps can be taken to mitigate the obtrusive effects while not compromising safety to the road user. 12.3.1 .6 Local Requirements. The l ighting requirements of the owner or other local authorities may be restricted by local bylaws or even defi ned u nder a predetermi ned master plan for the area. The designer needs to be aware of these facts and work within the prescribed parameters without compromising safety. Any safety Figu re 1 2-2. Intersection extents as defined by crosswalks. 2. With the a bsence of d e l i n eated pedestri a n crosswal ks, t h e calculation a rea sha l l be t h e area enclosed by the i ntersection stop bars extending across the departure lanes. (See Figure 12-3 for an exa mple of an intersection calcu lation setup uti l izing this defi nition.) concerns sha l l be discussed with those parties having j u risdiction for a satisfactory resolution. 1 2 .3.2 Intersection Lighting Requirements. This section provides recommended i ll u m i na nce levels for: • F u l l i ntersection l i g hting • Partia l intersection lighting • I ntersection deli neation l ighting 12.3.2.1 Defining the Intersection's Extents. In order to determine the lighting requirements for an intersection to be lighted, it is important to first understand the setup of the horizontal illuminance calculation grid. As mentioned in Section 12.1 .2, within an intersection, there are 32 potential vehicle-to-vehicle points of conflict, and 32 potential points LEGENO CALCULATIOH ARCA Fig ure 1 2-3. Intersection extents as defined by stop bars. of conflict between vehicles and pedestrians. These points can usually be contained as described below: 3. In the absence of the two previously described 1 . The a rea from the outside edge of pedestrian conditions, the ca l culation area sha l l be the a rea crosswa l k to outside edge of pedestrian crosswal k enclosed by the connection of the radius return on opposing legs o f the intersection. (See Figure of each i ntersection leg. (See Figure 1 2-4 for 1 2-2 for a n example of a n intersection calculation an exa mple of an intersection calcu lation setup setup uti l izing this defi nition.) util izing this defi nition.) 1 2-5 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 1 2.3.2.2 Full I ntersection Lighting. The val ues for fu l l intersection l ighting a re based on the principle that the a mount of l ight should be proportiona l to the classification of the i ntersecting roadways and equal to the sum of the va l ues used for each separate roadway. The val ues included in Table 12-1 are the recom mended average maintai ned i l l u m i na nce levels for fu lly lig hted intersections of continuously lig hted roadways, based on street classification and pedestrian vol umes. The 1----'- CURB ltAOIUS T£RMll<AT10 INTO TAHO[NT CURB SECTI ON L£0£NO CALCULATIOH AR£A Figure 1 2-4. Intersection extents as defined by curb returns. recommendations assume an R2 or R3 pavement type. If the i ntersecting streets a re not continuously lig hted, a partial l ig hting system may be utilized. Because of the nature of intersection calcu lations, the vei l i ng l u m i na nce ratio is not a valid req u i rement because Some intersections may include some of these elements it cannot be calcu lated. However, it is recommended on certa in legs and not others. I n these cases, the a bove that i n order to m i n i mize glare, the use of l u m i naires ra nked criteria shall be uti l ized for each leg. with high-angle-candlepower should be avoided in a l l insta nces o f ful l intersection lighting. With in the area defined a bove, some elements may be left out of the i ntersection cal cu lation as these elements Pole placement: I n most cases, the recom mended do not contai n a potential point of conflict as shown in horizontal i l l u m inance levels for intersections can be Figure 12-1 (see Section 12.1 .2). ach ieved by using combination signal and l u m inaire poles. Where fu l l roadway lighting that ties i nto the These elements include: • Islands. Pai nted and raised islands areas should be precluded from the intersection calculation area, as these are not intended to be accessed by veh icular intersection is present, the spacing of the poles on the a pproach road should be desig ned to synchronize with the pole locations for the intersection. traffic. • Channelized right turn only lanes. As this type Light poles should be positioned i n advance of the of lane does not contai n conflict points, there is no crosswa l ks to i m p rove visibil ity in the crosswa l k by need to light it to intersection lighting levels or to providing i mproved vertica l i l l u m ina nce and positive include it withi n the i ntersection area. contrast. Figure 12-5 shows the general arrangements. Table 1 2-1 . Pavement llluminance Criteria for Full I ntersection Lighting (Lux/Fe) Functional Classification Pedestrian Activity Level Classification High Medium Low favg /Emin Major/Major 34/3.2 26/2.4 1 8/1 .7 3.0 Major/Col lector 29/2.7 22/2.0 1 5/ 1 .4 3.0 Major/Local 26/2.4 20/1.9 1 3/1.2 3.0 Col lector/Col lector 24/2.2 1 8/ 1 . 7 1 2/1 .1 4.0 Co llector/Local 21/2.0 1 6/1.5 1 0/0.9 4.0 Local/Local 1 8/1 .7 14/1 .3 8/0.7 6.0 12-6 I ntersections, Roundabouts and Crosswalks 1 2 .3.2.3 Partial I ntersection Lighting (Isolated with l ow h i g h-an g le candlepower be a req u i rement in I ntersections). U nder certai n circu mstances, lighting a l l instances of partial i ntersection l ig hting. may be appropriate at a n isolated i ntersection where Pole placement: Poles for partia l i ntersection l i g hting conti nuous lighting does not exist. In this situation, the may be placed as shown i n Figure 1 2-5. The fig u re application of partial l ighting wou ld be appropriate. shows th ree typical examples, including three-leg, fou r­ Partial lighting consists of a lighting system that is put in leg and "T" i ntersections. place to provide l ig hting at points of potential conflict. It is not considered continuous, but some of the rules that apply to conti nuous l ighting w i l l apply in the design of partial l i g hting, such as pole placement, and calcu lation proced u res. In the case of isolated intersections, the conflict area is, by definition, that area that encom passes a l l of the Typical Three-Leg Intersection conflict points. A determi nation of conflict points can be found i n Figure 1 2.1 , Section 1 2.1 .2. Figures 1 2-2, 1 2-3, and 1 2-4 provide illustrations of the extent of the conflict areas to be lit (refer to Section 12.3.2.1 Defining the I ntersection's Extents). Main Road Partial l ig hting should meet the l ig ht levels for the type of road where the i ntersection is l ocated. Isolated l1! ( intersections being l i g hted should meet the partial i ntersection l i g hting reco m m e ndations. The val ues included in Table 1 2-2 are the recommended average Typical Four-Leg Intersection maintained l ight levels for the a rea being lig hted, based on the road classification and pedestrian volu mes. With RoaA ,.iLtminaire Pde (TypK:a� I partial lighting, the crossroad l i g hting is not considered in the determination of the light level, and the va l ues r Main can be read d i rectly from the tab le. The l ighting should ' meet the correspond ing uniformity ratio for the main road type and pedestrian activity level. Because of the natu re of i ntersection calcu lations, the Typical "T" Intersection vei Ii ng I u mina nee ratio is not a val id req u i rement because it can not be calculated. However, it is recommended Figure 1 2-5. Typical pole placement for partial that in order to m i n imize g la re, the use of l u m inaires intersection lighting. Table 1 2-2. Pavement llluminance Criteria for Partial (Isolated) Intersection Lighting Pavement Classification Road Classification Uniformity Ratio Rl R2 & R3 R4 lux/fc lux/fc lux/fc Eavg/Emin Major 6/0.6 9/0.8 8/0.7 3.0 Collector 4/0.4 6/0.6 5/0.5 4.0 Local 3/0.3 4/0.4 4/0.4 6.0 1 2-7 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 1 2.3.2.4 I ntersection Delineation (Beacon Lighting). 1 2 .4 Roundabouts When simple identification of a n isolated intersection is The required, then the use of beacon l i g hting is appl icable. p u b l ication U.S. Federal H i g hway Ad m i n istration (FHWA) FHWA-RD-00-067, Roundabouts; An Informational Guide3 states: As the name implies, beacon lighting consists of a single l u m i na i re i nsta l led simply for the pu rpose of marking "For a roundabout to operate satisfactorily, a driver must be able to enter the roundabout, move through the presence of a n intersection. In order to reduce glare, the circulating traffic, and separate from the circulating only low l ight output l u m i n a i res and low mounting stream in a safe and efficient manner. To accomplish this, a driver must be able to perceive the general layout and operation of the intersection in time to make the appropriate maneuvers. Adequate lighting heig hts should be used, and the installation should not adversely affect the safe operation of the roadway. For roads with fou r or fewer lanes, it is recommended that a single HID luminaire source of 1 50 watts or less (or LED equ ivalent) be used at 9.1 -meter (30-ft) mounting should therefore be provided at all roundabouts." This Recommended Practice provides guidance for the heights or lower. For roads with more than fou r lanes, it lighting of roundabouts only, and does not include other is recommended a 250-watt or less HID source (or LED circular intersections. This section, therefore, provides equiva lent) be used at a mounting height of 9.1 to 1 3.7 m horizontal i l l u m inance recommendations within the (30 to 45 ft). The installation of delineation lighting should roundabout and vertical illuminance recommendations for not adversely affect the safe operation of the roadway. locations where pedestrians are likely to be present. Other considerations discussed include glare, light trespass, and Pole placement: Poles for delineation lighting may be pole placement to help achieve proper lighting and to placed on a ny quadra nt of the intersection; however, it better define the traffic elements within the roundabout. is prefera ble that the l u m inaire arms be oriented toward the road with the highest traffic vol u me. Typical pole A modern roundabout is a form of circu lar intersection layouts are shown i n Figure 12-6. distinguished from other circular intersections in three principal ways. First, a l l traffic entering the intersection m ust yield to traffic a l ready circulating within the circu latory roadway. Second, approaches, or "legs," of the roundabout are channelized, most often with raised splitter islands, forcing entering vehicles to deflect to the M • in Road _ � _ _ _ � � � Luminaire Location A t J right on entry. Third, appropriate geometric curvature is ������ Use One Pole Only Select Luminaire Location A, B, o r C provided to ensure that travel speeds at entrances and on the circulatory roadway are less than 50 km/h (30 mph). There are other differences as well, described in Section 12.4.2. An illustration of a typical sing le-lane roundabout and its key features are shown in Figure 12-7. [ According to the FHWA's Roundabouts: An Informational Luminaire Location Main Road Guide,3 due to a g reat red uction in the n u m ber of conflict points (see Figure 1 2-8) as wel l as the low absol ute and relative speeds between various vehicles, roundabouts (in pa rticular sing le-lane rounda bouts) have been proven to be significantly safer than traditional signal­ controlled or stop-controlled intersections. Figure 1 2-6. Typical pole locations for delineation Physical features of a roundabout usual ly include raised lighting. splitter islands between entering and exiting traffic, a 12-8 I ntersections, Roundabouts and Crosswalks CiraJatory roadway width raised center island, yield lines as well as edge line mark­ ings, unique signage, illumination, and when appropri­ ate, pedestrian features (sidewalks, ramps, crosswalks). Though advisory speeds may be posted, speeds are not set through signage. Speeds through a roundabout are self-enforced by the geometry of the raised features. Other features not common to all rou ndabouts but often necessary i nclude truck aprons and entry flares. Truck a prons a re genera l ly slig htly raised above the rest of the roadway but a re mountable and traversable Figure 12-7. Key roundabout features. by the rear wheels of larger vehicles that cannot track within the normal striped lane. Entry widths have a g reater effect on roundabout capacity than any other single featu re. The approach roadway thus often flares out just ahead of the rou ndabout for a wider entry width. The width of the circ u l a r roadway is general ly constant and at least as wide as the widest entry. Bicycle lanes are not a l l owed4 on the circu lar roadway within a modern rou ndabout. Bicyclists should mix with veh icle traffic, as experienced riders can generally attain speeds similar to motor vehicles within rou ndabouts. Approach designs often provide for children and less capable bicyclists to exit the roadway and cross as pedestrians. Good desi g n and operation a lso d ictates that no parking be a l l owed along or in close proximity to the circu lar roadway. I n addition, centra l islands should be designed to d iscourage pedestrian activity. Although centra l islands, and to a lesser deg ree spl itter islands, can be la ndscaped, often extensively, la ndscaping needs to be done with critica l attention paid to stopping sig ht l i nes, intersection sight triang les (incl uding a clear view of pedestrian crosswal ks and ra mps), and clear zones for errant vehicles. Wel l over half the crashes i n rou ndabouts result either from drivers fa i l i ng t o yield to c i rcu lating traffic or from single vehicle crashes with • � Q roadside cu rbs or other obstacles. Diverging Merging Crossing 1 2.4.1 Key Dimensions and Categories. The FHWA pro motes six categories of rou ndabouts with the basic design characteristics shown in Table 1 2-3. Figure 1 2-8. Vehicle conflict points in an intersection (left) and a roundabout (right). (Sou rce: Roundabouts: An Pedestria n crosswa l ks generally a re l ocated 6 to Informational Guide, 3 Exhibit 5-2) 1 5 meters (20 to 50 feet) back from the entry yield 12-9 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway and Parking Facilities Table 1 2-3. Roundabout Categories and Typical Characteristics (Source: FHWA-RD-00-067, Roundabouts: An Informational Guide3) Mini Roundabout U rban Compact Recommended Maximum Entry design speed 25 km/h (15 mph} 25 km/h (15 mph} 35 km/h (20 mph} 40 km/h (25 mph) 40 km/h (25 mph} 50 km/h (30 mph} Maximum number of entering lanes per approach 1 1 1 1 1 1 Typical inscribed circle diameter 13 m to 25 m (45 ft to 80 ft) 25 to 30 m (80 to 100 ft) 30 to 40 m (100 to 1 30 ft) 45 to 55 m (150 to 180 ft) 35 to 40 m (115 to 1 30 ft) 55 to 60 m (1 80 to 200 ft) Splitter island treatment Raised if Raised and Raised and Raised, with possible, extended, extended, Raised, with Raised, with crosswalk cut crosswalk cut crosswal k cut crosswalk cut with with crosswalk cut crosswalk cut if raised Design Element Typical daily service volumes on on 4-leg roundabout (veh/day) 1 0,000 1 5 000 , U rban Urban Rural Rural Sing le-Lane Double-Lane Single-Lane Double-Lane 20,000 Refer to Chapter 4 procedures 20,000 Refer to Chapter 4 procedures I . Assumes 90 degree entries and no more than four legs l i ne and typical ly cut thro u g h the spl itter island at 12.4.2 Roundabout Traffic Operations. In considering grade. Crosswa l k designs req uire detectable warnings l i g hting for a rou ndabout, it ca n be instructive to (e.g., tru ncated domes) a l i g ned perpendicular to the understa nd of how traffic operations at roundabouts crosswa l k on either side of the splitter island as wel l differ from those at other types of i ntersections, and as nea r t h e bottom o f ramps entering and exiting the in particular, how they differ from the most common street. intersection type, cross intersections. The FHWA Guide states that for satisfactory operation, Traffic operations at rou ndabouts differ from those of a d rivers m ust be able to enter the rou nda bout, move typical cross intersection in that: through circulating traffic, and separate from the • circulating traffic in a safe and efficient manner, and intersection but rather before the i ntersectio n . that to accomplish this, d rivers m ust be able to perceive That is, pedestrians cross t h e spl itter island at a the genera l layout and operation of the i ntersection in location that is a veh icle-length before the yiel d time to make appropriate ma neuvers. line at a roundabout. T h i s difference i s im portant i n that the location where i ll u m i nation is needed A clear view of pedestrian activity is also of g reat for pedestrians is away from the roundabout itself. im portance. Good delineation (e.g., pavement markings It is i m portant to keep in mind that the search and signage) should be provided at all roundabouts, behavior by a driver approaching a roundabout and l i g hting should be provided. for pedestrians is simpler because d river need not check for conflicting vehicles at the same time. The l i mits of a roundabout a re shown in the b lue-shaded areas in Figure 1 2-9. The area to be i ll u m i nated includes At a rou ndabout, pedestrians do not cross at the • At a roundabout yield line, a d river need only check the tapers for each leg. While Figure 1 2-9 shows the one d i rection, to the l eft, rather than th ree directions nose of the separation island within the calcu lation for conflicting traffic at a cross i ntersection (from area, the pu rpose of the rou ndabout lighting l i mits is to the left, from the rig ht, and oncoming). At the include the crosswa l k within the calcu lation l im its. rou ndabout yield l i ne, a d river need not check for 1 2-1 0 I ntersections, Roundabouts and Crosswalks Figure 1 2-9. Typical roundabout limits. • • • pedestrians (they will be passing behind h i m; see The improved visibility provided by l i g hting wil l benefit Figure 1 2-8), only for a pproaching vehicles a nd traffic operations at a roundabout by supporting flow, cyclists from the left. through put, and safety. From the poi nts described At a cross intersection, the head l i g hts of the vehicle above, all rou ndabo uts should be i l l u m inated with i l l u m i nate the roadway a head i n the d i rection specia l attention g iven to pedestrians and cyc l ists, of travel. This is not the case for i l l u m i nation if p resent. For flow and through put, the primary by veh icle head l i g hts at a rounda bout. At a contribution of lighting is to m i n i m ize delays caused roundabout, the headlights of a vehicle at the yield by u ncertainty at critical locations when a pproaching line of a roundabout a re poi nted ahead toward and circulating the rou nda bout. Whether considering the circulating roadway on the right and do not safety or delay, it is essential to remember that l ighting i l l u m inate confl icti ng traffic from the l eft. does not work alone; rather, it is supported by road Drivers need not necessarily stop under yield signs and markings. This system of sig ns, markings, and control at a rou ndabout, but rather yield the right lighting is critical to maintain in a n appropriate balance of way to crossing pedestrians and traffic, including such that neither operations nor safety is adversely cyclists, from the left on the circulating roadway. affected. (Refer to FHWA Manual on Uniform Traffic Driver speeds a pproaching a n d traversing the Con trol Devices4 for further information.) rou ndabout a re slowed by the deflection induced by the splitter island and the circular island in Operations the center of the i ntersection; this is a sign ificant appropriate use of l ig hting at a roundabout include: difference from cross intersections, where speeds of entering vehicles a re not slowed. • issues that can be m itigated by the U ncertainty at the roundabout approach. The positive aspects of roundabout design-Le., 12-1 1 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities provide 12.4.3 Design Considerations for Roundabouts. As significant benefits i n daylight ca n potentia lly described previously, a rou ndabout is a type of circular c u rvature • and chan nel izati o n -that become a major challenge i n darkness. When intersection where entering traffic yields to circu lating a pproaching a n u n l ig hted rou nda bout, a driver traffic and all traffic is slowed by appropriate geometric may be u ncerta in about the nature of the roadway features. For a roundabout to operate satisfactori ly, a l l geometry and may slow or stop inappropriately, users-drivers, pedestrians, a n d cyclists-need t o be thus causing u nnecessary delay. Roadway lig hting able to enter, circulate around, and exit the roundabout can highlig ht key elements of the rou ndabout wel l in a safe and efficient manner, and pedestrians need enough in advance t o a l leviate this uncertainty to be a ble to safely use crosswa l ks. To accompl ish and support steady and efficient flow in nighttime this, each user has to perceive the genera l layout and operations. operation of the i ntersecting roadways in time to make Pedestrian crosswalks. As with any i ntersection, the appropriate ma neuvers. pedestrians a re the most vul nerable users at a roundabout. Though vehicle speeds are lower at a The l i g hting of rounda bouts serves two primary roundabout, col l isions between automobil es and purposes: pedestrians can sti l l be fatal. Thus, a n im portant • It makes the roundabout visible from a d istance, fu nction for l ig hting at a rou ndabout is to ensure thus i m p roving the rou nda bout's perception to that a ny pedestrian in the crosswal k is visible to approaching users. vehicles approaching and exiting the rou ndabout. • It makes key conflict areas more visi ble, thus i m proving users' perception of the layout of the I n addition, sidewa l k a reas i n adva nce of the crosswa l k a re a lso important for the safety of users. intersection and their perception of one another as Lighting i n this area can a lert d rivers to i nattentive they use the roundabout. pedestrians who m ig ht inadvertently step into the • crosswa l k without l ooking. Lighting provides a distinct benefit in that it draws the Vehicle tracking around the circulatory roadway. attention of the users to the problem of navigation. The The circulatory roadwayofa rou ndabout is pu rposely lighting should mark a break in the linear path of the given a small rad i u s in order to generate slower approaching roads by emphasizing the circular aspect of speeds. This tight cu rvature creates a situation in the roundabout and thus improve the users' understand­ darkness where the vehicle headlig hts w i l l likely ing of its operation and their task ahead. The contribution not su pport the d river's view of the road. I n other that lighting makes made to the safety of the roundabout words, the tight curvature of the roadway w i l l tend will depend on the design of the lighting system.5 to make the driver look more to the left, perhaps thro u g h the front portion of the side window, than Key design considerations i n desig ning l ig hting for i n the direction the head lights are i l l u m inating. As roundabouts i nc lude: the head light beams are tangential to the roadway, • i n a rou ndabout due to the constra i ned cu rve the d river is looking i nto darkness while negotiating • The effectiveness of vehicle headlig hts is l i mited a n u n l i g hted rou nda bout. Roadway l i g hting can rad i us, making the roadway l ig hting system very support the driver i n this situation. i m portant for nighttime visibil ity of obstructions and hazards. Cyclists negotiating a roundabout. In a single-lane roundabout, cyclists will most likely be encouraged • to merge with traffic and circulate the roundabout in the vehicle lane. Roadway lighting can provide Approach lighting should provide g ood perception of the presence of the roundabout. • If continuous roadway l i g hting is not present, needed safety to cyclists at the approach to the transition l ig hting should be provided for d river roundabout, where they begin to mix with the traffic, adaptation and should extend for a distance of and throughout the circulatory roadway, where they approxi mately 80 meters or g reater from the are integrated in the traffic stream. rou ndabout on each a pproach. 12-1 2 I ntersections, Roundabouts and Crosswalks • As a way to m i n i m ize glare and l i g ht trespass, stud ies (see Section 12.6.1 ). For the purpose of this l u men l imits should be esta blished within the solid Recom mended Practice, it is recommended that the angles described in Section 2.6.3, by lighting zone average vertical i l l u m inance for a series of points 1 .5 and appl ication, and the use of flood lig hts should meters (5 ft) in height, a l ong the centerline of the be avoided. crosswa l k, extending to the edge of the roadway, and In a reas where l ighting zones6 have been esta blished spaced at 0.5 meters (1 .65 ft), for each d riving d i rection, by the a uthority having j u risdiction (AHJ), particular be equal to the req u i red horizontal i l l uminance and consideration should be given to the im pact of the u n i formity for the rou ndabout as described i n Section lighting system on adjacent properties. (See Table 12.4.5.1 . 4-1 i n Chapter 4 for descriptions of the lighting 1 2 .4.4.3 Pole Placement Recom mendations. zones. Pole placement is critical in creating good visibi lity i n a roundabout. Figure 1 2-10 and Figure 1 2-1 1 show how 1 2.4.4 Lighting Recommendations for Roundabouts. order to provide criteria that will adeq uately mounting the l ig hting system around the peri meter of address the visibil ity of the roadway, pedestrians, and the roundabout and on the approach road can differ hazards thro u g h a roundabout, this document uses a greatly from a l ig hting system contained within the combination of horizontal i l l u m ina nce for the roadway center island of the rounda bout, in results atta ined. It is and vertical i l l u m i nance in the crosswalks (if present). also i m possible to meet the vertical lighting level in the l l l u m i na nce calculations should be performed accord ing crosswa l ks unless approach l ig hting is used. Because of to the procedures described i n Section 1 2 .4.5. this, it is reco mmended that lighting be placed around In the perimeter of the roundabout at locations on the 12.4.4.1 Horizontal llluminance Recommendations. a pproach side of the crosswalks, if present (see Section Table 1 2-4 incl udes the reco m m ended average 12.4.5 Roundabout Calculation Example for pole mai ntained l ight levels for roundabouts, based on road placement advice). Even if pedestrian crosswal ks are classification and pedestrian vol u mes. This table reflects not present in the rou ndabout, the general approach the same values for intersections outlined in Table 1 2-1 recom mended by this docu ment produces a n efficient, (Section 12.3.2.1 ). The levels in this table a re also those comfortable desig n. recom m ended for continuously l i g hted streets. For rou ndabouts on roadways that a re not conti nuously The simulated images in Figure 1 2-10 i l lustrate the l i g hted, the val ues for the loca l/loca l classification potential visibility benefits. (Note signage and pedestrian sho u l d be used. visibi lity as wel l as that of the vehicle a head.) The l u m i na i re photometry and layout meet the i l l u m ina nce 12.4.4.2 Vertical l l l u m i nance Recommendations. criteria cited in Table 1 2-4 and Section 1 2 .4.4.2. The Vertical i l l u m inance in crosswalks to assist the d river s i m u l ation in Figure 12-1 1, i l l u strating center island in identifying pedestrians has been the topic of several l i g hting, does not meet those criteria. Table 1 2-4. Recommended Pavement llluminance for Roundabouts, Based on Pedestrian Activity Classification Pedestrian Activity Classification Functional Classification High Major/Major 34/3.2 Major/Col lector 29/2.7 Major/Local 26/2.4 Col lector/Col lector 24/2.2 Co l lector/Local 21/2.0 Lo ca I/Lo ca I 1 8/ 1 . 7 I I I I Medium 26/2.4 22/2.0 20/1.9 1 8/1 .7 1 6/ 1 . 5 1 4/ 1 . 3 I I I I Low favg/Emin 1 8/1 .7 3:1 1 5/1 .4 3:1 1 3/ 1 . 2 3:1 1 2/1 .1 4:1 1 0/0.9 4:1 8/0.7 6:1 1 2-1 3 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Figure 1 2-1 0. Roundabout with perimeter lighting Figure 12-1 1 . Roundabout with center-island lighting (recommended). (not recommended). 1 2 .4.4.4 Roundabout Calculation Grids. The calcu lation g rid (see Figure 1 2-12) for the horizontal i ll u m i na nce in a rou ndabout should include the a rea i mmediately before the splitter islands (at the start of the gore) and conti nue throughout the rou nda bout. Center islands need not be incl uded i n the horizontal i l l u m inance ca lculation. The grid spacing should be no g reater than 2 meters (6.6 ft). The calcu lation g rid for the vertical i l l u minance (Figure 1 2-13) in the crosswalk portion of a rou ndabout should include a series of points at a height of 1 .5 m (5 ft), centered in the crosswalk, and spaced at 0.5 m (1 .65 ft), for each d riving direction. The vertical i l l u m inance Figure 1 2-1 2. Calculation grid for horizontal illuminance calculations should be performed with the light meter in roundabouts. aimed toward the direction of a n approaching d river whose eyes are at a height of 1 .5 m (5 ft) above 1 2 .4.5 Roundabout Calculation Example. The the roadway at a distance of one safe stopping sight fol l owing is an example of the calcu lations recom mended distance, as determ ined by the rou ndabout speed (see for a rou nda bout, with some tips for desig ners using Tables 1 2-5 and 1 2-6). this method for the first time. 1 2-14 I ntersections, Rounda bouts and Crosswalks Reviewing the plans and d iscussions with the hig hway engi neers establ ished the fol lowing: • Fu nctional classification: Major/Local • Pedestrian usage: H i g h • Entry d e s i g n speed: 3 5 km/h (20 mph) • Speed with in rou ndabout: 20 km/h ( 1 2 mph) 12.4.5.2 Calcu lation Method . From Table 1 2-4, Section 1 2 .4.5.1 , the recom m e nded averag e m a i ntained horizontal i l l u m inance for this roundabout is 26 Ix (2.4 fc). The recom mended u niformity is 3:1 (favglfm ;n). Figure 1 2-1 3. Crosswalk vertical calculation grid. As recom mended in Section 1 2 .4.4.2, the vertical i l l u m inance in the crosswalks should be equal to the Table 1 2-5. Safe Sight Stopping Distances in req u i red horizontal i l l u m i na nce for the crosswa lk. Roundabouts Therefore, for this exa m p l e the average vertica l Design Speed (km/h) Computed Distance (m) 10 8.1 20 18.S 30 31.2 40 46.2 50 63.4 i l l u m inance at a height of 1 .5 m (5 ft), centered in the crosswa l k, in both d i rections, should be 26 Ix (2.4 fc). For this particular design, a flat-glass cobrahead style l u m i naire is selected. It is i m portant in the design of rou ndabouts to establish l u men l imits with in the solid angles for BUG ratings, described in Section 2.6.3. Since there is no g l a re calcu lation method that can be easily applied to the geometry of a roundabout, the Table 1 2-6. Design Speeds in Roundabouts use of l u minaires that meet the appropriate BUG rating Number of Lanes Inscri bed Circle diameter (m) Radius (m) Speed (km/h) Single 30 11 21 Single 35 12 23 Single 40 16 25 A h orizontal ca lculation g rid should be placed on the Single 45 19 26 roadway with g rid point spacing not g reater than 2 Double 50 17 25 m (6.6 ft) in each direction. The a reas of the splitter Double 55 20 27 island and central island should be excluded from the Double 60 23 28 calcu lation g rid (see Figure 1 2-14). Double 65 25 29 Double 70 28 30 h e l ps m i n im ize the a mount of g la re generated by the l ighting system. It a lso helps m i n im ize light trespass to adjacent properties. Another line of grid poi nts should be placed along the centerline of the crosswa l k, at a height of 1 .5 m (5 ft), spaced at 0.5 m (1 .65 ft) for the vertical i l l u minance 12.4.5.1 Sample Roundabout. The rou ndabout under consideration is a single-lane u rban rou ndabout i n a rather dense residential area of single and m u ltiple­ fa m i ly dwel lings. This roundabout has three legs and is calcu lation. This calculation is performed with the l ig ht meter poi nted in the d i rection of the a pproaching d river's eyes. (See Figure 1 2-1 5.) Hint: Many lighting calcu lation packages refer to this as "TV l l l u m inance," as it is often used to see whether sufficient i l l u m i nance is the intersection of a l ocal and a major road. Crosswal ks being provided from the vantage point of a television are provided at the rou nda bout. camera). 1 2-15 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Figure 1 2-14. Horizontal grid. 1 • ' . • •• • • HSP� I ,_71-l�'""' ION OF DRIVER'S EYE ; v 2 e: z 1 .2s URBAN SINGLE·LANE ROUNDABOUT DESIGN SPEED BASED ON INSCRIBED CIRCLE DIM1ETER Pro ect : A t ,. :.abeJJ H Pro ects r.o ri:fo nul Cale ve:e1ca l :r.Do:.ind Vert cal OUtbOUi':d Figure 1 2-1 5. Vertical grid and calculation summary. 1 2-1 6 I CalcTvoe I :uc.:r.1nance :ui.:::ii::ar.ce :11uir.1nar.ce 22 KP.l<H SO 20KMJH SPEED Unl.t.!11 Ave Max Mi.n L\:X 30 . '7 :L9 I Lux I ::e . 11 I ss . o I 9 . 5 LUX Z8 . 31 : e . oe 31.3 Zl.6 Ava/M.1n I Z . 96 l.l4 1 . 30 Max/Ml.n I S.H 1 . Zl 1 . 45 I ntersections, Rounda bouts and Crosswalks The d river location is one safe stopping sight distance from the crosswalk. With the g rids establ ished, the l u m i naires can then be added to the ca l culation model. As stated previously, peri meter l i g hting is recom mended. Note: FHWA's Roundabouts: An Informational Guide3 can be very beneficia l for information on stopping d istances and design speeds, as wel l as for other useful information. Figu re 1 2-1 7. A similar type of roundabout, provided as Calculations can be performed once the g rids have been established and the pole assemblies located. The l ig hting system may need to be adjusted several times u ntil the light levels recom mended in this chapter are met. 1 2 .4.5.3 Suggested Pole Locations. A good place to start locating poles is at the crosswa l ks. In order to meet the vertical i l lu m i na nce criteria, luminaires need an example. 1 2 .5 Crosswal ks at Intersections Vertical i l l u m i nance has been identified as an i m portant e l e ment in l i g hting crosswa l ks associated with intersections. Some stud ies have indicated significant safety i m p rovements with h igher vertical i l l u m inance va l ues. Higher levels of vertical i l l u m i nance produce a better positive contrast, which is further i mproved by vehicle headlights. to be placed on the approaching d river's side of the crosswa l k. When using typical roadway l u minaires, a In m ost cases, the recom mended horizontal illu m inance good location is approximately 0.7 "mo u nting heights" level s for i ntersections ca n be achieved by using away from the crosswalk. If higher l i g ht levels are com bination sig nal and l u m i naire poles. However, this required, e.g., those for the intersection of two major arrangement w i l l not typical ly provide optim a l vertical roadways, su pplemental poles may be needed. (See i l l u m inance within the crosswa l k a rea. Figures 1 2-16 and 1 2-1 7.) If vertical i l l u m ination is desired i n crosswa lks to improve pedestrian visibility, it is recommended the maintai ned average vertical levels meet or exceed the maintai ned average horizontal design levels for the intersection. For example, if the recom mendations for the horizontal lighting levels at an intersection are 27 l ux, then the vertical l ig hting level recommended in the crosswal k at a height of 1 .5 m should be 27 lux or greater. It is recommended that the vertical i l l u m ina nce grid be located at a height of 1 . 5 m (5 ft) along the centerline of the crosswal k, extend to the edge of the roadway, and have points spaced at 0.5 meters (1 .65 ft) apa rt and oriented in the direction of the approaching veh icle. The l ig ht meter should be pointed toward the a pproaching d river's eye heig ht, assumed to be 1 .5 m (5 Figure 1 2-16. Pole layout suggestions. ft) a bove g rade. 1 2-1 7 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Note: Recommendations for crosswa l ks in rou nda bouts 0 are provided in Section 1 2.4.5.2. There is a possibil ity of g la re from opposing vehicles 0 The crosswal k is located in a n area with high a m bient light levels 1 2 .6 Midblock Crosswal ks 0 A midblock crosswal k is a crosswal k that occurs at • locations other than at an intersection. The crosswa l k is located at a lighted intersection The l u m i na i re selected w i l l i nfluence the best mounting location and height of the l u minaire with respect to the crosswa lk. 1 2.6.1 Supportive Research. A study7 conducted in 2002 considered the l ight levels necessary for safety at • The vertical i l l u m i nance level that a l l owed d rivers to pedestrian crosswal ks. That study supports a n u pper­ detect pedestrians at adequate distances was the end vertical i l l u m ina nce of 40 l ux. same for H PS and MH sou rces; however, MH and other white l ig ht sou rces can provide better facial recognition and comfort for pedestrians. In 2008, a n extensive study8 was conducted by the U.S. Federal H ig hway Ad ministration (FHWA) and Virginia Tech Transportation Institute (VTTI) concerning the lighting of The report also incl udes some placement g u i da nce for crosswal ks. The purpose of the study was "to provide positioning poles before the crosswal ks (see Figure information to traffic engineers and lighting designers 1 2-1 8). regarding lighting parameters that i m pact the abil ity of drivers to see pedestrians in mid block crosswalks and to enable agencies to evaluate the potential effectiveness of l ighting designs." While some visibility concepts are discussed below, this report does not cover all aspects of nighttime visibility and the human visual system. The information is based on static and dynamic experiments performed at VTTI. From the report: "The initial static experi ment used the time it took for an observer to detect the pedestrian or su rrogate target as a metric for visibil ity, while the dynamic experiment used the d istance at which pedestrians or su rrogate targets were identified as the metric. Experimental cond ition variables included lamp type (high-pressure sod i u m, metal halide), vertical i l l u m i nance level (6, 1 0, 20, and 30 Ix), color of pedestrian clothing (white, black, and deni m), position of the pedestrians and su rrogates, and the presence of g la re." The findings and recommendations of the VTTI study ,, are: • A vertical i l l u mina nce level of20 Ix measu red at 1 .5 m (5 ft) from the road surface a l l owed d rivers to detect pedestrians in mid block crosswa l ks at adequate stopping distances under rura l conditions. • A h igher level of vertical i l l u minance might be - • t I r 'I "' •• - req u i red for crosswa lks if a ny of the fol lowi n g Figure 1 2-1 8. Crosswalk pole placement. (I mages courtesy conditions exist: of Paul Lutkevich/Parsons Brinkerhoff) 1 2-1 8 I ntersections, Rounda bouts and Crosswalks 1 2 .6.2 Design Crosswalks. Considerations for Midblock A m id block crosswa l k can potential ly be less safe for pedestrians than a crosswa l k at a n intersection because d rivers may n o t expect pedestrians to be crossing travel lanes at locations other than intersections. I mproving pedestrian visibility to d rivers is the main reason for lighting a mid block crosswalk. Historica l ly, the use of silhouette or negative contrast for the detection of a pedestrian was recommended. H owever, new research is showing positive contrast has many advantages, particularly when considering the reinforcement of positive contrast with head la mps.9 Figure 1 2-19 shows the differences between negative and positive contrast. Two calcu lated renderings that show the difference in visibil ity resulting from an i ncrease in the vertical i l l u m i nance, even though the average horizonta l i l l u minance in the crosswa l k remains the same, are shown i n Figure 12-20. Both renderings use a single 250-watt H PS l u m in a i re. The l u m i na i re i s mou nted d i rectly above a crosswal k in the lower fig u re, but moved to approximately 5 m in advance of the crosswal k in the u pper fig u re. The average horizontal i l l u m inance at the crosswa l k remains essentia l ly the same, but the vertical i l l u minance on the pedestrian is increased when the pole is placed in advance of the crosswa l k. This change Figure 1 2-20. Comparison of visibility in crosswalks with creates much g reater visibi l ity of the pedestrians in different pole placements. Figure 1 2-19. Negative contrast (left) and positive contrast (right). 1 2-1 9 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities the crosswa l k for the d river, as i l l ustrated in the u pper 1 2 .6.4 Lighting Recommendations for Midblock rendering. Crosswalks. 1 2 .6.3 Midblock Crosswalk Design Issues. 1 2 .6.4.1 Horizontal Luminance (for Roadway, If Required). 1 2 .6.3.1 Coordination with Other Elements. Horizontal l u m inance on the roadway, if It is the roadway is conti nuously lighted, shall meet or im portant that the l ighting of mid block crosswa l ks exceed the recommended levels defined i n Chapter 1 1, be coordi nated closely with other elements. Potential Section 1 1 .7. conflicting elements that may l i m it pole placement and 1 2.6.4.2 Vertical llluminance. mounting height include: Research shows that • Roadway geometrics and l i m ited road a l lowance maintai ned average vertical illum inance in crosswal ks • Overpasses, othe r of 20 to 40 lux will benefit visibil ity of the pedestria n.8 structures that may create shadowing on t h e a rea Research is ongoing as to what is the optimal level. It is pla nti ngs, b i l l board s, and recommended the designer consider a level of 20 lux for to be lighted • Sidewal ks, bi keways, street fu rniture, and other physical features associated with the roadway • Signage and signals • U nderground and overhead util ities areas with low pedestrian conflict, 30 lux for areas with medi u m pedestrian conflict and 40 l ux for a reas with high pedestrian conflict. 1 2.6.4.3 Pole Locations. To meet the recommended vertical i l l u m inance levels, poles need to be placed in 1 2.6.3.2 Clear Zone. Poles for midblock crosswa l k advance of the mid block crosswa l k. Exact p lacement l ighting c a n b e obstacles t o errant motor vehicles a n d wil l depend on va riables such as l u m i na i re optics, l u men should b e located s o as not t o compromise t h e safety output, and mounting height. of roadway users. Consideration of the clear zone and the use of breakaway devices on poles are key issues Where the roadway approaching the mid block crosswal k affecting l ig hting design. (Refer to Chapter 6, Sections is l i g hted, t h e pole spacing for t h e roadway should be 6.9.2 and 6.9.3 for more information.) desig ned to synchronize with the pole locations for the mid block crosswa l k. 12.6.3.3 Obtrusive Light. Midblock crosswal ks may be located in a reas where the control of obtrusive 1 2 .6 .5 Design Calculations. light is a concern. The designer should follow the for m i d b l ock crosswa lks may i n c l u d e both vertical recommendations outli ned i n Chapter 4 to mitigate i l l u m i n a nce calcu lations within the crosswa l k a n d Des i g n calcu lations obtrusive light. H owever, because the lighting of a l u m i nance calcu lations on t h e a pproach roadway i f m id block crosswalk enhances safety, l ig hting criteria t h e roadway a pproaching t h e crosswa l k is lighted. I f should not be compromised in order to meet loca lly t h e roadway approaching t h e crosswa l k is n o t lig hted, adopted l ig hting bylaws that may seek to l i m it obtrusive l u m i nance calcu lations are not req u i red. light. 12.6.5.1 Horizontal Luminance Calculations. 12.6.3.4 Local Requirements. The type of l ig hting for If the roadway approaching the crosswalk is lighted, the a specific area may be defined by l ocal req u i rements luminance level of the roadway shall be calculated to ensure in the form of a bylaw or a l ig hting master plan. The that the luminance level in the crosswalk meets or exceeds desig ner should contact the appropriate agencies to the criteria defined in Section 1 1 .7 for the roadway. If determine the content and extent of local req uirements. the roadway approaching the midblock crosswalk is not Eq ui pment used for a m idblock crosswa l k can be davit­ lighted, luminance calculations are not required. style, mast-arm, or truss-style l i g hting. Decorative post­ top lighting may also be considered if it suits project 1 2.6.5.2 Vertical llluminance Calcu lations. requirements. i l l u m inance calcu lations are req u i red in the crosswal k 1 2-20 Vertical I ntersections, Rounda bouts and Crosswalks to light the vertical su rface of pedestrians crossing the roadway. The calculation is performed i n the d i rection of the approaching vehicle. For two-way roads, both sides of the roadway shall be calculated. 12.6.5.3 Glare Calculations. G l a re c a l c u lations a re not req u i red for midblock crosswa l ks. However, it is recommended that flat-glass l u m inaires, mounted with the l u m inaire lens para l lel to the roadway, be used to minimize potential g l a re. If the roadway approaching the mid block crosswal k is l i g hted, t h e desig ner should meet corresponding vei l i ng l u m ina nce recommendations for the roadway. 1 2.6.5.4 Mid b lock Crosswa l k Calcu lation Grids. H orizontal g rid spacing for the roadway (required if the roadway approaching the mid block crosswal k is lig hted) sho u ld meet the requirements described in Section 1 1 .7.2. The calcu lation g rid within the crosswa l k is required on a vertical plane across the roadway, with o n ly a single line of calcu lation poi nts req u ired . (Refer to Section 3.2 .3.6 in Chapter 3 for point locations.) 12.6.6 Midblock Crosswalk Design Example. The design steps for a m idblock crosswalk a re less complex than for other types of roadway e lements; therefore, a step-by-step na rrative for the design example is not provided here. U nd e rta king an i ntersection mid block crosswa l k design may i nvolve n u merous l i g hting ca lcu lations using va rious l u mina ire optics, wattages, mounting heights, and locations through a "trial and adjustment" process u ntil the req u i red vertical i l l u m i na nce levels and uniformities are achieved. A typical calcu lation is shown in Figure 1 2-21 . Forth is example, l u minance calculations are not req uired on the roadway because the roadway approaching the crosswa l k is not lighted. Cobrahead style l u minaires with a flat g lass lens were used, mou nted on 9.0-meter poles. II l u m inance levels on the vertical g rid line slightly exceed the recommended average maintained vertical level of 40 l ux. 1 2-21 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities LUMINAIRE POLE YPICAL)1 WESTBOUND VERTICAL ILL MINANCE _ .... _ .-- ;" - .- .,,. ,,,,,.,.. - o'f 'o� €.c' 'io EAS BO ND VERTICAL I LUM I ANCE � � r - - .... - - - - .... c.. \1€. · \.. "I' "" CROSSWALK Arrcm lndlcale l rectlon of measurements O UTPUT RESULTS GRID MAINTAINED AVERAGE W-8 VERTICAL ILLUM INANCE E-B VERTICAL ILLUM INANCE Figure 1 2-21 . Design example for a midblock crosswalk. 1 2-22 4 1 . 1 lux 4 1 . 1 lux I ntersections, Rounda bouts and Crosswalks R E F E R E N C E S FOR CHAPTER 1 2 1. Box PC. Relig hting Kansas City, Missouri. The American City, Part IV; Jun 1 956. 2. Box PC. Major road accident reduction by i ll u m i nation. Was hington, DC: Transportation Research Board, National Academy of Sciences; 1 989. (Transportation Research Record 1 247). 3. Federa l H i g hway Administration. FHWA-RD-00-067, Roundabouts: An Informational Guide. Washington, DC: FHWA; J u n 2000. 4. Federal H i g hway Ad ministration. FHWA Manual on U niform Traffic Control Devices (MUTCD), 2003 ed., Revision 1 . Washington, DC: FHWA; Nov 2004. 5. 6. Transportation Association of Canada. Guide for the Desig n of Roadway Lig hti ng. Ottawa: TAC; 2006. I l l u m i nating Engineering Society. ANSl/IES LP-1 1 -20, Lighting Practice: Environmental Considerations for Outdoor Lighti ng. New York: I ES; 2020. 7. Hasson P, Lutkevich P, Anantha narayanan B, Watson P, Knoblauch R, N itzburg M. Field test for l ig hting to improve safety at pedestrian crosswa l ks. Proc 1 6th Biennia l Symp on Vis and Simulation. Iowa City, Iowa; 2002 J u n 2-4. 8. Federa l H i g hway Administration. FHWA-H RT-08-052, Report on Lighting Design for Midblock Crosswal ks. Washington, DC: FHWA; 2008. (Available as NTIS p u b lication n u m ber PB2008-1 06431). 9. Hartman K, Pritchard B, Jennings K, Johnson J, Knipling R, Mcgowan L, Oliphant M, Sa nft C. FHWA-Pl-2000-010, Europea n Road Lighting Technolog ies. Washington, DC: Federa l H i g hway Ad ministration; 2001 . 1 2-23 At-G rade Ra i l way Crossings Cha pter 1 3 CO N T E N TS 1 3.1 Design Considerations . . . . . . . . . . . . . . . . . . . . 1 3. 1 . 1 General Considerations 1 3. 1 .2 The Pu rpose o f Railway 1 3. 1 .3 1 3.2.1 1 3- 1 for the Trai n Cars 1 3-2 1 3.4.3 G l a re Calcu lations . . . . . . . . . . . . . 1 3-2 1 3.4.4 Calcu lation G rids . . . . . . . . . . . . . . . . . 1 3-2 . . . . . . . . . . . . . . . . . . 1 3-2 1 3. 5 At-Grade Rai lway Crossing Design Example . . . . . . Coord i nation With Other E lements Clear Zone . . . . . . . 1 3.2.3 Obtrusive Light . . . . . . . . . . . . . . . . . . . . Lighting Calculations . . . . . • . . . • . . . . . . . . . . . . . . . . . . . . . . 1 3-3 Vertical l l l u minance Calcu lations . . . . . . . . . . . . . . . . . . . 1 3-3 . . . . . . 1 3-3 . . . . . 1 3-3 . . . . . . . . . . . . . . . . . . . . . . . . . 1 3-4 1 3-2 1 3.3 Lighting Recom mendations . . . . . . . . . . . . . . . 1 3-2 1 3.4 for the Railway Crossing 1 3.4.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3.2.2 Horizontal Calcu lations . . . . . . . . . . . . . . . Pole and Luminaire Placement Design Issues 1 3.4.1 1 3- 1 Crossing I ll u m i nation 1 3.2 1 3-1 . . . . . . . . . . . . . 1 3-3 References for Chapter 13 . . . . . . . . . . . . . . . . . . . . . . 1 3-6 Cha pter 1 3 At-G rade Ra i l way Crossings A t-grade railway crossings consist of railway tracks that cross a roadway. They are norma l ly identified with rai l road crossing signs (cross-buck) and pavement markings. Proper l ighting of a n at-grade railway crossi ng will aid road u sers i n identifying the crossing, a ny irregularities in the pavement surface, the presence or absence of a trai n, and the presence of a train a pproaching the crossing. The lighting will also a l low recognition of pedestrians, cyclists or veh icles at or nea r the rai l road crossing. The goal is to i l l u m i nate pedestrians, cyclists, and the side of the train (vertical i l l u m ina nce), as wel l as the roadway (horizontal i l l u m i nance). 1 3.1 Desig n Considerations 1 3.1 .1 General Considerations. Poles and l u minaires • Nighttime tra i n operations • Low train speeds • B lockage of the crossing for long periods at n ig ht • Collision history ind icating that motorists often fa i l will be required for each approach to the crossing i n order to ach ieve both the req u i red horizontal t o detect trains or traffic control devices at n ig ht i l l u minance on the roadway and the required vertical i l l u mi nance on the sides of the tra i n cars. • Horizontal a nd/or vertical a l i g n ment of hig hway approach such that vehicle head l ig ht bea m does Tra nsport Canada's Grade Crossings - Handbook,1 not fa l l on the trai n u ntil the vehicle has passed the Appendix safe stopping distance M, Supplementa l E n g i neering Design G uidance for Vul nerable Road Users at G rade Crossi ngs contains i nformation and fig u res with notes relating to • • g rade crossing i ll u m i nation. Specifically, it states that for engineering design best practices to reduce site risk a nd H u m ped crossings where onco m i n g vehicle headl ights are visible u nder trains • Low a mbient light levels • A h i g h ly reliable source of power enha nce safety, secu rity, and visibility: "The crossing a pproaches and su rface(s) should be equipped with Restricted sight or stopping d istance in rura l a reas adequate i l l u m i nation to provide nightti me visibil ity to a l l users." This would include street lighting on a l l road a pproaches, sidewal ks, paths, or tra i l s in the vicinity of Lu minaires may a lso provide a low-cost a lternative to active traffic control devices on ind ustrial or mine tracks the crossing. where switching operations are carried out at nig ht. Although grade crossing i l l u m i nation is cu rrently not a 1 3.1 .2 The Purpose of Railway Crossing Illumination. regu latory requirement or standard, designers should The intent of rai l road g rade crossing l i g hting is to light consider using this l ig hting to enha nce safety, secu rity, the conflict a rea of the crossing for a l l road users. The a n d visibility, especial ly in urban bu ilt-up areas where conflict area is defi ned as the complete road cross vulnerable road users are present. section, i ncluding the shoulders, to 30 meters in front of the ra il track crossing in both d i rections (see Figure Accord ing to the FHWA Highway-Rail Crossing Handbook: 1 3-1). I ll u m i nation at a crossing may be effective in red ucing n i g httime collisions. I l l u m i nating most crossings is Lighting may be insta l led at and adjacent to the crossing technically feasible because nearly all crossings have to supplement other traffic control devices where an com m e rcial power ava i lable. I l l u m i nation may be engi neering ana lysis determines that better visibi l ity of effective u nder the fol l owing conditions2: the crossing and trains is req u i red. 1 3-1 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Conflict Area pedestrians on the roadway approaches to the crossi ng, and so that they do not block the visibi l ity of signals used to warn approaching vehicles of a train. 1 3.2 Design Issues Public Roadway 13.2.1 Coordination with Other Elements. It is i mportant that the l i g hting system for a n at-grade ra i l way crossing be coord i nated closely with other elements. Potential confl icting elements that may l im it pole placement and l u minaire mounting height i nclude: Figure 13-1 . Conflict area for railroad grade crossings • • In addition to l i g hting the conflict area of a ra i l road l i m ited road Overpasses, pla nti ngs, b i l l boa rds, and other to be lig hted • Sidewalks, bi keways, street fu rniture, and other physical featu res associated with the roadway adding auxil iary lig hts facing the train cars. 1 3.1 .3 Pole and Luminaire Placement. To meet the including structu res that may create shadowing on the area g rade crossi ng, it is recommended to provide added vertical i l l u m i na nce req u i rements recom mended i n geometrics, a l l owance where there is no stop bar. visibi l ity of the side of the train cars. This is achieved by Roadway • Signage • Railway geometrics and rai lway crossing features • U nderground and overhead utilities Section 1 3.3, shorter poles with l u m i naires o f higher than normal wattage may be req u i red. The use of 1 3.2.2 Clear Zone. Light poles for at-grade rai l way floodlights should be avoided, as the resultant glare crossings can be obstacles to errant motor vehicles and may reduce visibility for road users and tra i n operators. should be located so as not to compromise the safety If the auxil iary l u m inaires a re flood l i ghts, care shall be of roadway users. Consideration of the clear zone and taken in the a i m i ng of the l u m inaires in order to avoid the use of breakaway devices on poles are key issues excessive glare to motorists on either approach road. affecting l i g hting desig n . (Refer to Section 13.1 .3 Pole and Luminaire Placement, as well as Sections 6.9.2 A single pole should be located in advance of each crossing and 6.9.3 in Chapter 6, for additional i nformation.) to meet the vertical and horizontal i l lumina nce criteria recommended. Where continuous lighting is present or 1 3.2.3 Obtrusive Light. proposed on the approach roads, the pole spacing for may be located i n a reas where the control of obtrusive the roadway should be designed to synchronize with the l i g ht is a concern. The designer should fol low the pole locations for the railway crossing. At-grade rai lway crossings recommendations outlined i n Chapter 4 to m itigate obtrusive l i g ht. However, because the lighting of a n The poles should not be located closer than 10 meters at- g rade railway crossing enhances safety, l i g hting from the railway right of way and fa r enough away from criteria should not be compromised to meet locally the tracks so if they are knocked down, they wil l not fa l l adopted l ig hting bylaws that may seek to l i m it obtrusive onto t h e tracks. Pole placement s h a l l b e i n conformance l i g ht. with the AASHTO Manual for Assessing Safety Hardware (MASHP and the AASHTO Roadside Design Guide.4 1 3.3 Lighting Recommendations Care should be taken in locating the l u m i naires in a Where the l i g hting on the roadway a pproach is way that will l i mit the g la re to d rivers, bicyclists, and contin uous, the roadway should meet the l u m i na nce 1 3-2 At-Grade Railway Crossings requirements described in Chapter 1 1 , as the continuous rai l way roadway l ighting w i l l provide adequate l ig hting of the calculations for the roadway and vertical i l l u m inance conflict a rea. Where the l i g hting on roadway approach calculations for the side of the train. cross i n g s include h o rizontal i l l u m i na nce is not continuous (no lig hts), the horizontal illu minance leve l s and u niformity ratios defi ned in Table 1 2-2 13.4.1 Horizontal Calculations for the Railway Pavement llluminance Criteria for Partial (Isolated) Crossing. Horizontal i l l u m inance calculations for the Intersection Lighting (see Chapter 1 2) sha l l be appl ied a pproach road should be undertaken as defined for for the conflict areas. partial i ntersection l ig hting in Chapter 12, Section 12.1 .4. To provide vertica l i l l u m ination of the tra i n cars, a n average o f at least 1 0 lux should be maintai ned on the 1 3.4.2 Vertical llluminance Calculations for the Train vertical p lane l ocated at the first track for each approach Cars. Vertical i l lu m i nance calcu lations are req u i red for within the right of way (see Figure 13-1 ). The l im its of the sides of the train cars, with the light meter pointing the calcu lation a rea should be as described in Section in the d i rection of the approaching road user. 1 3.4.4. 1 3.4.3 Glare Calculations. Glare calcu lations a re not Beca use of the natu re of rai lway crossi ngs, the req u i red for at-grade rai lway crossings. However, it is vei l i ng l u m inance ratio is not valid because it can not recom mended that flat-g lass l u m i n a ries, mou nted with be calcu lated where the roadway l i g hting is non­ the l u m i naire lens para llel to the roadway, be used to conti nuous. It is, however, recommended that in order m i n i mize potential glare. to m i n imize glare, l u m inaires with low i ntensity at high 1 3.4.4 Calculation Grids. Calcu l ation g rids for ra ilway crossings a re illustrated in Figure 1 3-2. ang les be used. • Where the l i g hting on the roadway is conti n u ous, 1 3.4 Lighting Calcu lations the h o rizonta l g ri d s p a c i n g for the roadway As described above, design calculations for at-grade s h o u l d m eet the req u i re m ents descri bed i n 1 .sm rr YP.) Figure 13-2. Typical calculation grids for railway crossings. 13-3 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Chapter 3. This distance is measured from the stop bars if there are such (see Figure 1 3-1 , Section 1 3.1 .2), otherwise from the edge of the right of way (see Figure 13-2). Where there are m u ltiple tracks, the right of way extends well beyond the tracks, and there is no stop bar. I n that case, the 30-meter distance shall be applied beginning at approximately 5 m from the edge of the track. • The vertical calcu lation g rid for the side of the train is located along the edge of the railway track ties, extending 4.5 m vertica l ly above the ties and horizonta l ly to a point 1 .5 m beyond each edge of the roadway, roadway a l l owance, or sidewalk. The g rid point spacing should be 0.5 m . The light meter should be pointed toward the a pproaching road user. For roads with two-way traffic, vertical calculations should be performed for each direction of a pproaching traffic. 1 3.5 At-Grade Railway Crossing Desig n Example The design steps for the l ighting of a rai lway crossing are less complex than for other roadway elements. Therefore, a step-by-step desi g n na rrative is not provided here. An example of a typical design is shown in Figure 1 3-3. U ndertaking the l ighting design may involve nu merous l i g hting calcu lations with different combi nations of l u m i n a i re optics, wattages, m o u nting heig hts, and locations, using a "trial and adjustment" process u ntil the req uired i l lu m i na nce levels and un iform ity ratios are ach ieved. 1 3-4 At-Grade Railway Crossings TRACKS LUMINAIRE POLE SEE ENLARGEMENT BELOW OUTPUT RESULTS GRID MAINTAINED AVG./MIN. AVERAGE APPROACH ROAD 1 7.4 LUX 2.5:1 1 0.0 lux 2.2:1 HORIZONTAL ILLUMINANCE RAI LWAY TRAIN CARS VERTICAL ILLUMI NANCE VERTICAL ILLUMINANCE ENLARGEMENT LUMINAI RE SCHEDULE SYMBOL T DESCRIPTION FILE LUM ENS LLF M400A CUTOFF GE1 006.IES 27500 0.75 Figure 13-3. Lighting calculations for a railway crossing with non-continuous approach lighting. 1 3-5 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities R E F E R E N C E S FOR CHAPTER 1 3 1. Transport Canada. Grade Crossings - Handbook. Ottawa: Tra nsport Canada; 201 9. 2. Federal H i g hway Ad ministration. FHWA-SA-1 8-040, FHWA H i g hway-Ra i l Crossing Hand book, 3rd ed.; Washington, DC: FHWA; 201 9. 3. American Association of State a nd Hig hway Tra nsportation Officials. AASHTO Manual for Assessing Safety Hardware (MASH). Washi ngton, DC: Federal Hig hway Adm i nistration; 201 6. 4. American Association of State a nd Hig hway Tra nsportation Officials. AASHTO Roadside Design Gu ide, 4th ed. Washington, DC: Federa l H i g hway Ad min istration; 201 2. 1 3-6 Tu n n e l Lig hti ng Cha pter 1 4 CO N T E N TS 1 4.1 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-1 1 4. 1 . 1 Types ofTunnels . . . . . . . . . . . . . . . . . . . 1 4- 1 1 4. 1 .2 Tu nnel Topology Terms . . . . . . . . . . . . . 1 4- 1 1 4.5.2 Negative Contrast (ALO-NC) . . . . . . . 1 4- 1 3 1 4.5.3 1 4.2 Tu nnel Design Considerations . . . . . . . . . . . . 1 4-3 1 4.2.1 Traffic and Roadway Geometry . . . . . 1 4-3 1 4.2.2 Tu nnel Architecture and Materia l s . . 1 4-4 1 4.2.3 Visibi l ity a nd Adaptation 1 4.5.4 1 4.6. 1 Ease of Mai ntenance . . . . . . . . . . . . . . . 1 4-6 1 4.3.2 N i g httime Adaptation . . . . . . . . . . . . . . 1 4-9 1 4.4 Tu nnel Lighting Recommendations . . . . . . . 1 4-9 1 4.7 1 4.6.2 Threshold and Tra nsition Zones . . . . 1 4- 1 8 1 4.6.3 Tu nnel I nterior Zone . . . . . . . . . . . . . . 1 4- 1 9 Lighting and Electrical Equipment for Tu nnels . . . . . . . . . . . . . . . . . . 1 4-19 1 4.7.1 Light Sou rces . . . . . . . . . . . . . . . . . . . . . 1 4- 1 9 1 4.4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-9 1 4.7.2 Equipment and Lu minaires . . . . . . . . 1 4-21 1 4.4.2 Daytime Pavement Luminance . . . . . 1 4-9 1 4.7.3 Tu nnel Physical Conditions and 1 4.4.3 N ighttime Pavement Luminance . . . 1 4- 1 0 1 4.4.4 Non-roadway Surface Illumination . . 1 4- 1 1 1 4.4.5 Curved Tu nnels . . . . . . . . . . . . . . . . . . . 1 4- 1 1 Related Luminaire Characteristics . . 1 4-21 1 4.7.4 E lectric Power Su pply and Distribution . . . . . . . . . . . . . . . . . . 1 4-22 1 4.4.6 U n iformity Ratios . . . . . . . . . . . . . . . . . 1 4- 1 2 1 4.4.7 Veiling Lumina nce Ratio . . . . . . . . . . . 1 4- 1 2 and Switching Systems . . . . . . . . . . . . 1 4-22 1 4.4.8 Fl icker Effects . . . . . . . . . . . . . . . . . . . . . 1 4- 1 2 1 4.8 Maintenance Considerations . . . . . . . . . . . . 1 4-23 1 4.4.9 Tunnel Lighting Operation Modes . . . 1 4- 1 3 1 4.8.1 Genera l . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4-23 1 4.4. 1 0 Tu nnel Emergency Lighting . . . . . . . 1 4- 1 3 1 4.8.2 Other Factors . . . . . . . . . . . . . . . . . . . . . 1 4-23 1 4.4. 1 1 Lighting for Wayfinding . . . . . . . . . . . 1 4- 1 3 1 4.5 Lum inance Va l ues i n Threshold Zone . . . . . . . . . . . . . . . . . . . 1 4- 1 4 Daytime Adaptation at the Tu nnel Approach . . . . . . . . . . . . . . . 1 4-6 Wide and Narrow Tu nnels . . . . . . . . . 1 4- 1 4 1 4.6 Tu nnel Calcu lations: Methods of Determination of Luminance Criteria . . . . 1 4-14 1 4.3 Tu nnel Design Issues . . . . . . . . . . . . . . . . . . . . . 14-6 1 4.3.1 Asymmetrical Light Distribution Positive Contrast (ALO-PC) . . . . . . . . . 1 4- 1 4 for the Driver . . . . . . . . . . . . . . . . . . . . . . . 1 4-6 1 4.2.4 Asymmetrical Light Distribution - Light Application Techniq ues . . . . . . . . . . . 14-1 3 1 4.5.1 1 4.7.5 Measurement, Control, 1 4.9 Calculation Example: Lseq Method for Determining L1h . . . . . . . . . . . . . . . . . . . . . 14-24 Symmetrical Light Distribution . . . . 1 4- 1 3 References For Chapter 14 . . . . . . . . . . . . . . . . . . . . 1 4-26 Cha pter 1 4 Tu n n e l Lig hti ng T he objective of this chapter is to provide information to assist engi neers and designers i n determining l ighting needs, recom mending solutions, and eva l uating res u lting visibility at veh icular tunnel a pproaches and i nteriors. The i nformation in this chapter is i ntended also for use by admin istrators charged with the responsibi lity of providing a safe visual envi ron ment withi n a tunnel d u ring both daytime, nighttime, and emergency conditions. This chapter deals entirely with lighting and associated 1 4.1 Definitions systems and does not g ive advice on construction The terms defined in this section are specific to tunnels practice. It is neither i ntended as, nor does it establ ish, and tunnel lighting. Other roadway l i g hting terms are a legal standard for tunnel l ighting systems. Its purpose defined in the Glossary. is to provide recommendations for the design of new tunnel lighting systems, and it is not intended to be appl ied to existing l ig hting systems until such systems are redesigned. It has been prepared to advance the art, science, and practice of i l l u m i nation as they pertain to tunnel l i g hting in North America. I ncl uded in this chapter a re discussions of: the treatment of tunnel and u nderpass portals, wal ls, and ceil i ng 14.1 .1 Types of Tunnels. tunnel: A structure over a roadway that restricts the normal daytime i l l u m i nation of a roadway section such that the d river's vision is su bstantially d i m i nished. A tun nel covers a roadway and produces a shadow that l i mits the abil ity of the d river to see objects, including obstructions, with in the tunnel. su rfaces; selection of l ig hting equipment, including light sources; l i g hting system mai ntenance; and l ig hting short tunnel: A tunnel that is less than 122 meters (400 economics. Special req u i rements for pedestrians are feet) in length. not addressed in this docu ment. Pedestrian u nderpass l ig hting is covered in Chapter 1 1 . depressed tunnel: A tunnel that has sloped approach zones to a llow for below-grade passage under roads, The em phasis o n providing electric lighting o r daylighting rivers, or u rban areas. in vehicular tunnels enables a motorist to maintain speed and safely navigate. The basic design criteria for tunnel divided tunnel: A stru cture that consists of two lighting are outlined in Section 14.4. Tun nels may vary separate enclosures, each designated to accommodate considera bly in req u i red threshold-zone l u m i nance one d i rection of traffic flow. values, depending on variables such as geographic orientation, geometric design, traffic vol ume, traffic speed, service levels, light sources used, and modes of l ight application. The lighting designer, therefore, should consider the factors that affect the visibility conditions, discussed in Sections 14.2, 14.3, and 14.5. This chapter can not address every scenario that a tunnel undivided tunnel: A structure that consists of a common enclosure to acco m modate traffic flow i n both directions. u nderpass: A struc t u re of length and physica l confi g u ration that do not substantially l i m it a d river's l ighting desig ner may encou nter, but it does describe abil ity to see objects a head. For nighttime i l l u m ination, influencing factors of which the designer should be underpasses can be classified as short or long. aware. The designer is a lso enco u raged to make onsite visits, construct real or virtual models, and use other 14.1.2 Tunnel Topology Terms. The fol lowing terms techniq ues to help in design eva l uation and aid in used to describe tunnel topol ogy a re i llustrated in eng ineering j udgement. Figure 1 4-1 . 14-1 ANSl/IES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities A = Point of Observation B = Adaptation Point C = Portal 0 = 22° to 25° A B c Tunnel c f d a = approach b = adaptation distance c = t h reshold zone d = transition zone e = i nterior f = exit zone Figure 14-1 . The primary external and internal areas associated with and affected by tunnel lighting design. adaptation point: The point where the stru ctu ra l designer should review this issue with the operator of opening o f the porta l becomes the principal feature i n the tunnel to determine whether the use of exit zone the d river's field of view. From this point forward, the l ighting is needed. (For additional i nformation, refer eye w i l l be influenced solely by the l u minance of the to the CIE Publication 88, Guide for the Lighting of Road tunnel interior. An observer height of 1 .45 m above the Tunnels and Underpassses.1) roadway is used i n consistency with the assumptions described i n Chapter 3, Section 3.2.3.1 .2. The roof point of observation: The point from which the d river of a veh icle creates a range of windshield cut-off angle fixates on the opening of the tunnel to identify hazards of 22° to 25°. Actual height and windshield cutoff may on the tunnel roadway. This is equal to 1 stopping sight vary for truck and cargo vehicles. The distance back distance (SSD) from the tunnel portal (see Table 14-1 ). from the porta l where the sight line of the cut off angle This is also the point at which adaptation begins. l i nes u p with the top of the tunnel opening determines the adaptation point. Any angle from 22° to 25° may be interior zone: The area within the tunnel after the used. end of the transition zone, where eye adaptation is complete. adaptation distance: The d ista nce between the adaptation point and the portal . The form ula to calcu late mounting height, MH: The vertical distance between adaptation distance is: the roadway surface and the center of the apparent light source of the l u m i naire. adaptation distance, m = [(portal height, m) - 1 .45]/ tan ¢ , where ¢ = 22° to 25° point of fixation: A point or object in the visual field at which the eyes l ook and on which they a re focused. approach: The external roadway area leading to the tunnel, between the fixation point and the portal . portal: The plane of entrance into the t u n nel, where the roadway changes from u ncovered to covered. exit zone lighting: Exit zone l ighting is not d iscussed or recom mended as part of the tunnel lighting system primary line of sight: The l i ne connecting the point of except when circu mstances make it a req u irement. The observation and the point of fixation. 14-2 Tunnel Lighting Table 1 4-1 . AASHTO Stopping Sight Distance on Wet Pavement in Meters (ft) by Percent Grade Downgrade (%) Traffic Speed, I I I I I I L U pgrade (%) km/h (mi/h) 0 3 6 9 3 6 9 3S (20) 3S (1 1 5) 3S (1 1 6) 37 (120) 3 8 (126) 33 (1 09) 33 (1 07) 32 (1 04) 40 (2S) so (lSS) so (1 S8) so (1 6S) S3 (173) 4S (147) 44 (143) 43 (140) so (30) 6S(200) 66 (20S) 70 (21S) 74 (227) 61 (200) S9 (1 84) S8 (179) 60 (3S) 8S (2SO) 87 (2S7) 92 (27 1 ) 97 (287) 80 (237) 77 (229) 7S (222) 6S (40) 93 (30S) 96 (31S) 1 01 (333) 1 08 (3S4) 88 (289) 8S (278) 82 (269) 7S {4S) 1 1 0 (360) 1 1 5 (378) 1 2 2 (400) 1 30 (427) l OS (344) 1 0 1 (33 1 ) 9 8 (320) 80 (SO) 1 3 0 (42S) 136 (446) 1 44 (474) 1 S 4 (S07) 1 2 3 (40S) 1 1 8 (388) 1 1 4 (37S) 90 (SS) 1 60 {49S) 1 64 (S20) 1 74 (SS3) 1 87 (S93) 1 48 (469) 1 41 {4SO) 1 36 (433) 1 00 (60) 1 8S (S70) 1 94 (S98) 207 (638) 223 (686) 1 74 (S38) 1 67 (S lS) 1 60 (49S) l OS (6S) 1 97 {64S) 209 (682) 222 (728) 240 (78S) 1 87 (612) 1 78 (S84) 1 7 1 (S61) 1 1 5 (70) 223 (730) 23S (771) 2S2 (82S) 272 (891) 210 (690) 200 (6S8) 1 93 (631 ) 2SO (820) 263 (866) 281 (927) 304 (1 003) 234 (772) 223 (736) 2 1 4 (704) 1 20 (7S) - I I I I I I J Table notes: The speed and distance columns only correspond to their SI or U.S. Customary System equiva le nt; i.e., if determining the SSD for a posted speed in kilometers per hour (km/h}, use the value shown in m; if using miles per hour {mi/h}, use the va l ue shown for ft. Source: A Policy on Geometric Design of Streets & Highways, 2 Chapter 3. threshold zone: The area i nside the tunnel between 1 4.2 Tu nnel Design Considerations the portal and the beg i n n i ng of the transition zone. This is the first stage of the eye's adaptation from the 14.2.1 Traffic and Roadway Geometry. dayti me l ig ht level outside the tunnel to the lower levels inside. Even when sunscreens a re used, the l ength of the 14.2.1 .1 Traffic. When designing a tunnel lighting system, threshold zone is stil l measu red from the tunnel porta l . traffic speed and volume should be taken into account. The length o f t h e threshold zone should b e equal t o the SSD for the tunnel's design speed less the adaptation distance. transition zone: The area between the threshold zone and the interior zone, which a l lows motorists to ach ieve appropriate eye adaptation by incremental ly red ucing Higher speeds place increased demands on d river discretion and responses; these in turn are influenced by the eye adaptation process, with higher levels of i l l u mination needed (see Table 14-1 [see Section 14.1 .2] and Table 14-2 [see Section 14.4.2]). A higher traffic volume inherently implies a need to maintain the flow of traffic. The perception by the motorist of light within the tunnel, as the motorist approaches and enters the portal, the level of l u m ina nce req u i red in the threshold zone will help encourage the motorist to maintain speed, and to that of the i nterior zone. The total length of the thus help to maintai n the flow of traffic. transition zone can be as long as 12 to 25 seconds of travel at posted speed, based on threshold l ig ht l evel The yearly average n u m ber of vehicles that pass throug h (see Figure 14-1 2, Section 1 4.6.2). a tunnel with in a 24-hour period for a l l lanes i n one 14-3 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities d i rection of a single-direction d ivided t u n nel, or both in u nderpasses (see definition in Section 1 4.1 .1) or directions for a bidi rectional undivided tunnel, is the structures less than 25 m (80 ft) i n length. The related Averag e An nual Daily Traffic (AADT). It is a n im portant 0% va l ues shown in Table 14-2 i l lustrate that for such factor for determining not o n ly tunnel l u m i na nce levels, u n d e rpasses supplemental daytime l i g hting is n ot but also q u a l ity of lighting, l ig hting equ ipment types, req u i red. and mai ntenance and operation proced u res. For n i g htti m e pavement l u m i na nce, underpass As part of the eva l uation of existing tunnel l i g hting l i g hting should be treated in the same m a n ner as systems and thei r associated existing l ig ht levels and the conventional nighttime roadway lighting for the desig ns, five years' worth of tunnel crash data are often u nderpass approaches; that is, lighting for nighttime eva l uated and compared to crash data on the non­ cond itions only and at levels and u niformities similar tunnel sections of the approach road to see how wel l the to the through roadway. When the conventional cu rrent light levels fu nction in red ucing visibil ity-based n i g httime lighting levels and u niformity on the roadway crashes. Current tunnel lighting standards are based a pproaches a re adversely affected by the u nderpass on visibil ity-based models and not d i rectly correlated structu re, then the u nderpass can be classified as "long" to crash rate. When crash data a re availa ble, they are a n d may req u i re additional lighting per the desig ner's often more predictive than visi bility-based models at j u d g ment. determining appropriate l ighting for safety at specific instal lations. Based on the results, one ca n deduce When whether l ig ht levels should be reduced, maintained, incl uded in a vehicular underpass, then pedestrian or pedestrian sidewa l ks or bicycl e lanes a re or increased. For example, m i n i ma l crashes at a tunnel supplemental l ighting should be considered for these approach and i n the threshold zone would indicate that specific a reas of the underpass. maintaining l ig ht levels would be a ppropriate. Higher crash nu mbers at a tunnel a pproach would suggest 14.2.2 Tunnel Architecture and Materials. that an i ncrease in threshold light levels might be needed . This type of eva l uation is best performed by 14.2.2.1 General. Coordination of the tunnel lighting a traffic eng ineer experienced in a n a lyzing crash data system with the architectural, structural, and civil designs and should consider the type of crash, e.g., rear-end is essentia l . Design team coord i nation should occur atthe or sideswipe, which may be more related to entrance begi n n ing of the project and continue throughout the visi bility issues. design process. Tu nnel lighting systems a re expensive to 1 4.2.1 .2 Divided and Undivided Tu nnels. Traffic flow in that ultimately m i n i m ize constructions costs, operation d ivided and undivided tunnel structures differs in many costs, and maintenance costs should always be appl ied. construct and operate. Coordi nated design techniq ues respects. Divided tunnels a re regarded as offering safer traffic flow. I n divided tunnels, there is almost 14.2.2.2 Pavement. no possibility for head-on col lisions, and in the case pavement will have a considerable effect on the a mo u nt The reflectance of the tunnel of m u lti-lane divided tunnels, lane occupancy is more of l i ght req u i red in the tunnel. The visibility of an object even ly distributed than in und ivided structu res. on the pavement w i l l vary with the l u m i nance contrast. Lu m i na nce contrast is infl uenced by the reflectances The designer should consider the operational of the pave ment and objects, the d i recti o n a l requirements of the tunnel, including possible reversible orientation o f t h e electric l ig ht sou rce, and t h e a mo u nt la nes, bidirectional traffic, and maintenance procedures of interreflected l i g ht in the t u n n e l (see Section based on traffic. 14.2.2.5). Portland cement concrete (PCC) pavement has a higher total reflectance factor, but might not 1 4.2.1 .3 U nderpasses. As shown in Table 1 4-2 enhance contrast because of its predomina ntly diffuse Section 1 4.4.2), no supplemental t h resh old reflectance characteristics. Smooth black asphalt has a lighting is req u i red for daytime pavement l u m inance lower total reflectance factor but may i m p rove contrast (see 14-4 Tu nnel Lighting due to the presence of some specu lar reflections. The be recta n g u l a r or arched and may i nclude textured or pavement type should be closely coordi nated with the grooved walls. The a rched cross-section and textu red lighting application techniq ue. It should be noted that su rfaces assist in contro l l ing noise, and a re often possible future asphalt overlays would affect pavement recom mended by acoustical engineers. However, such reflectance characteristics and conseq uently cou l d su rfaces absorb l ig ht as well as noise. Arched portals reduce the l u m inance i n the tunnel. may permit g reater contribution of daylight toward the threshold zone. 14.2.2.3 The Portal a nd Its Architectural Surround. exterior portal su rfaces and increase the luminance of 1 4.2.2.5 Reflective Characteristics of Road, Wall, and Cei ling Materials. Si nce tunnel l ig ht levels are interior su rfaces will likely red uce these lighting costs. expressed as l u m i na nce (reflected lig ht), the reflective Design techniques that m i n i m ize the l u m i na nce of Life-cycle economic a nalysis of the t u n n e l l i g hting cha racteristics of the road surface are critical for lighting system may well reflect long-term savings when calculations. When the tunnel is new and there is no appropriate materials and fi nishes a re selected. existing road, the designer needs to ascerta i n from the Architectural treatments of synthetic su rfaces and the b e used and then select t h e most appropriate r-table proper authorities the type of road su rface that w i l l areas su rrou nding the porta l can enhance the ada ptation (see Section 3.3.1) for the calculations. I n the event process. The porta l and the structural elements near the that the tunnel and road a l ready exist, the designer has portal should be fi nished with su rfaces that have a low two options: to use a n esta bl ished r-table, or to have reflectance. Concrete can be mixed with various dark the road su rface analyzed and a customized r-table agg regates and pigments or finished with a dark sta i n . developed. Using a n established r-table is the most Landscaping or vegetation s h o u l d be used wherever economical but can be less accurate; it is possible that, possible. to some degree, the design l evels will not correlate with field measurements. The designer should i nform the Some vehicular tunnel designs incorporate sunscreens, solar g a l le ries, and other s i m i l a r devices as design team and proper authorities of this possibility. an Extracting a core sam ple of the tunnel pavement and intermediate level between the outdoor l i g hting and sending it to a lab or measuring it onsite is expensive the portal, to reduce the effective daylight intensity but w i l l yield more-accurate results. at the portal. In such situations, the threshold and transition-zone l u m i nance levels a re reduced by steps if Tu nnel wall su rfaces may be finished with u ntreated the screened daylight a rea is a l l or part of the threshold rock, PCC, epoxy pai nt, concrete sealer, or g lazed zone. using cera mic tiles. The maintai ned reflectance coefficient sunscreen or solar gal lery desig ns, as some may be of u ntreated rock will be approximately 7%, u ntreated susceptible to dirt or snow accu m u l ation, thus creating PCC a bout 20% to 40%, and g lazed tiles a bout 45% to Caution should be exercised when serious maintenance problems a nd/or red uction of their 60%. The use of these materia ls wil l have an effect on effectiveness i n regulati ng light levels. tun nel l u m inance calculations, luminance u niformity, a n d object contrast. The selection of architectural treatments at the portal and its surrounding a reas is typically outside of the From a l i g htin g perspective, treated su rfaces with tunnel l i g hting designer's scope of work. However, higher reflectivity are preferred. It is recom mended that the tunnel lighting designer should bring the effects treated wal l su rfaces be of an easily maintainable, non­ of treatments to the design team's attention as part of specular materia l having an initial reflectance of at least project coord ination. 50% (e.g., epoxy paint coatings). 14.2.2.4 Cross-Sectional Features. The tunnel cross In tu nnels where cei l i ng reflectance wil l contri bute to section can influence l ight i nter-reflection and options the utilization of light, these su rfaces should be finished for l u m i naire placement. The tunnel cross section may sim ilarly to the wal ls. For l ig ht appl ication techniq ues 14-5 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities not utilizing u p l ight, ceilings may be u nfin ished or light and dark) detrimental to the driver's performance pai nted with dark flat paints for ease of mai ntenance will occur. beca use the reflected light contribution is neg l i g i ble. 14.2.3.2 Traffic Speed. Since adaptation to lower As with other architectural treatments (see Section l u m i nance levels under dynamic conditions is relatively 14.2.2.3), the selection of road, wal l, and ceiling materials slow, traffic speed is of g reat i m portance in determ ining is typica lly outside the tunnel l i g hting designer's scope the req uired l u m inance va l u e i n the threshold zone. of work. However, the tunnel l ighting designer should For exa mple, a motorist approaching a tunnel entrance bring the effects of these materials to the design team's at a relatively low speed, e.g., 40 km/h (25 m i/h), and attention as part of project coord i nation. observing the tunnel portal at a distance of 1 50 m (492 ft) w i l l have a pre-adaptation period of 1 3 seconds 14.2.3 Visibility and Adaptation for the Driver. before entry i nto the t u n ne l, permitting sign ificantly lower l u m inance val ues in the threshold zone. A motorist 1 4.2.3.1 General. D u ring dayl ight hours the eye is travel i ng at 80 km/h (S O mi/h) will have only 6.5 seconds adapted to the high l u m i nance l evels of the outdoor for eye pre-adaptation. Thus, the demand for visual e nvironment. When the eye is exposed to h i g h adaptation will be more severe, and sign ificantly higher l u m i nance levels, it h a s l i mited ability t o discern su rfaces l u m i nance val ues wil l be req u i red i n the threshold zone. with low l u m i na nce. When d rivers approach a tunnel portal and cannot see inside the tunnel, due to the In this cha pter, posted speeds, rather than design difference between outdoor l u m i na nce and t u n n e l speed, have been used when determining the l ighting interior l u m i nance, they may slow down or brake. This is req u i rements. The posted speed is the legal l imit for known as the black hole effect. a pproaching and passing thro u g h a tunnel. If a tunnel owner or operator determines that the roadway l ig hting To overcome the black hole effect, the tunnel lighting design speed l i mit should be higher than the posted system should provide enough l ight to enable a motorist speed, l i g hting i m pacts should be considered a n d approaching the tunnel to clea rly see the roadway and discussed with t h e design tea m. other tunnel su rfaces inside the portal. To accomplish this, a su bstantial a mo u nt of light sho u l d be produced 14.2.4 Ease of Maintenance. i n the threshold zone in order to reach a n acceptable closures for repair and m a i ntenance of l u mi na i res, reduction from the exterior l u m i na nce so that the eye l u m i na i re locations should be ca refu lly considered can adapt (see Chapter 2, Section 2.2.S). The length during the design phase of the project. Lu m i n a i res that of the threshold zone is determ i ned by subtracting include means for q u ick disconnection a llow for easier To m i n i m ize lane the adaptation d istance from the SSD. Appropriate repair outside of the operating tunnel environment. threshold zone lighting over this distance will enable Add itional i nformation may be found in Section 1 4.8 a motorist to see inside the tunnel and respond to a and i n Chapter 9, Section 9.6. hazard. O n ce the eye is no longer exposed to exterior 1 4.3 Tu nnel Design Issues l u m i nance, a transition can be made to a lower l evel of tunnel interior lighting that is economical and safe. 14.3.1 Daytime Adaptation at the Tunnel Approach. The transition should a l low time for the d river's visual system to physica lly adjust to low l evels of i l l u m i nation. 14.3.1 .1 General. To determine the req u i rements for If the threshold zone is too short in relation to the the daytime l u m inance levels in the threshold zone, speed of travel, the time available for d river ada ptation the l ig hting designer should assess the level of exterior will a lso be too short, resu lting in a black-out effect. I n l u m i nance to which the eye is adapted. High-lum inance add ition, i f t h e transition zone is too short, a screening su rfaces in proximity to the portal will enha nce the phenomenon (i.e., a defined and perceptible l i n e of black hole effect and, accord ingly, necessitate higher 14-6 Tu nnel Lighting l u m inance level s i nside the tunnel threshold. This If the sun is close to the viewing angle of the porta l subject is discussed further in Section 14.4.2. during an approach to a tunnel, the l u m i na nce of the 14.3.1 .2 Solar and Tunnel Orientation. The presence A depressed tunnel portal, which permits a direct line of of the sun in or near the approach viewing angle of sig ht to the sun at low viewing angles, w i l l accentuate the sky wil l be very high, creating a high veiling l u m i na nce. the tunnel portal creates a severe i l l u m ination design problem. An example wou ld be an approach to a tunnel problem. This occurs with east-west tunnels at the under a river: the viewing angle of the portal during east porta l just prior to sunset and at the west portal a pproach to this type of tunnel wou ld likely include a shortly after sunrise. It can a lso occur in north-south tunnels at the north portal, especially d u ring winter months at more-northern latitudes. ANS/I/ES LP-3-20, very high sky l u m ina nce, thus resulting in a high vei ling l u m i nance for the d river. The o n ly possible mitigation to this phenomenon is to rely on motorists to shield their Lighting Practice: Designing and Specifying Daylighting for Buildings3 contains i nformation on how to determine eyes or, perhaps more realistical ly, for the j u risdiction solar altitude and azimuth at any location and time of having a uthority to i ntentionally and a ppropriately day. It is often helpfu l to plot a polar g raph of the sun's red u ce traffic speed at the tunnel a pproaches d u ring l ocation around a specific tunnel portal. An example is these extreme times of day that permit a direct line of g iven in Figure 1 4-2. sig ht to the sun. Lseq Cone 28.4 lseq 56.8 SOU TH Figure 14-2. An example of a solar plot for a tunnel. 14-7 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities 1 4.3.1 .3 Sky. The sky is usua lly the second-hig hest 14.3.1 .5 Exterior Su rface Luminance. The l u m i na nce of l u m i nance "surface" to be considered when exami ning a material is dependent on the a mount of light striking daytime visual adaptation. The l u m ina nce of the it and its reflectance cha racteristics. Dark colored sky varies with the location of the sun, geographic materials have a l ower reflectance than light colored latitude, weather (cl ouds or h u m id ity), and atmospheric materials and genera l ly w i l l have a lower l u m ina nce particu lates. Sky l u minance is a lso discussed i n ANSI/ given the same a mo u nt of l u m i nous i ntensity. Materials /ES LP-3-20, Lighting Practice: Designing and Specifying Daylighting for Buildings. 3 The amount of dayti me sky seen by the motorist d u ring the approach to a tunnel w i l l g reatly depend on the topography a round the tunnel portal. For example, there may be very little sky i n the field of view around the portal i n mountainous, forested, or u rban areas. Conversely, the view of the tunnel porta l from the can have varying degrees of specular and non-specu lar (diffuse) reflective characteristics. I n general, smooth su rfaces have more specular characteristics than rou g h, u n even su rfaces. During the day, the luminance of surfaces around the portal wil l vary with the position of the sun. Surfaces that are in full sunlight in the morning may be in shadow in the afternoon. A specular surface may reflect sunlight toward approaching traffic at one time of day and away at fixation point i n areas with flat topography can include another, with the resulting surface luminance varying by su bstantial amounts of sky. I n general, the more sky a factor of ten or more. When the sun is very high in the viewable d u ring the approach, the h igher the roadway sky, the specular reflection of sunlight off vertical surfaces l u m i nance req u i red at the tunnel entry. is directed mainly downward, and off horizontal surfaces 1 4.3.1 .4 Daylight Contribution. The i m pact of daylight as they do when the sun is at lower angles. Non-specular penetration at both the entry and exit portals (see Figure surfaces reflect light i n all directions, and the luminance 14-3) can contribute sign ificantly to the measured L seq they present to a motorist is only moderately dependent value (equivalent vei l i ng l u m i nance; see Section 1 4.6.1) on the position of the sun. A specular surface that reflects upward, so many of these surfaces do not appear as bright at a tunnel entrance and the L1h (threshold l u m inance; see Section 14.6.1) required withi n the tunnel. The contribution is also observer-location dependent and is therefore different for bid irectional and sing le-direction tunnels. sunlight toward the motorist can force the motorist to adapt to a very high luminance level. The position of the sun with respect to the roadway, portal, and portal surroundings should be exam ined because of the potential for specu lar reflection from these su rfaces toward a m otorist approaching the tunnel. Specular reflection of s u n l ig ht off roadway su rfaces usua l ly occurs when the sun is at or near the a pproach viewing angle. U nder this circu mstance, the l u m i nance of the roadway can be as high as that of the sky. Specular reflection from the portal to the motorist usual ly occurs when the sun is behind the motorist. Nearby buildings and retaining wal ls can also reflect sunlight and adversely affect d river performance. Because of their gene ra l ly low reflecta nce, trees, shrubbery, brush, g rass, and other fol iage will typical ly have low l u m i nance, and therefore their presence enhances the adaptation process. When analyzing the Figure 14-3. An example of daylight contribution in a l u m i nance of foliage, consideration should be g iven to short tunnel. seasonal changes in appearance. 14-8 Tunnel Lighting Natura l rock has relatively l ow reflective characteristics, Figure C-2 i n Annex C illustrates eight different tunnel depending on its materia l and texture (see Section a pproach scenes used in determ ining threshold-zone 14.2 .2.5). i l l u mination levels.) The presence or absence of snow i n sunlig ht has a Section 14.6 provides actual methods for determ ining significant effect on the l evel of exterior l u m inance l u m i nance criteria val ues with in the tunnel. within the field of view. The presence of snow will esta blish the basis for the highest exterior- l u m inance 14.4.2 Daytime Pavement Luminance. design scenario, due to its h i g her reflectance, but the daytime l i g hting is to be provided in a tunnel of a g iven Whether i m pact of snow should only be considered when it is a length w i l l depend on a n u mber of factors. Some of predominant rather than occasional cond ition d u ring these factors a re subjective, but the designer needs to winter months. make an assessment based on tunnel orientation and seasonal solar location as to whether dayl ighting w i l l 14.3.2 Nighttime Adaptation. At nig ht, the d river is adapted to a typically low l u minance environment. Nightti me tunnel lighting should be similar to nightti me roadway lighting, provided that the level of roadway i l l u m i nation is consistent with the recommendations i n this docum ent. (Note: N i g httime tunnel roadway l u m ina nce should be no g reater tha n 3 times the tunnel-approach roadway l u m inance levels.) affect t h e visibi l ity o f objects within t h e tunnel. One major factor is the amount of daylight penetration the tunnel's construction a l lows via openings in the tunnel's walls or cei l ings. When designing tunnel l i ghting, the i m pact of daylight penetration a l ong the tunnel sides, via openings at the top of the structure, and at both the entry and exit portals should be considered; structu res with open piers, s loped a butment wal ls, and other openings 1 4.4 Tu n nel Lighting Recom mendations a l low g reater daylight penetration and visi bility withi n 14.4.1 General. The main objective in tunnel lighti ng design is to provide a l ighting system that meets the visibility req u i rements for daytime and nighttime conditions in a g iven tunnel. The task for a designer is not a sim ple one, particularly in the case of a new tunnel when often o n ly partial information about the portal and the approach roads is available d uring desig n . Procedu res for t u n n e l l ig hting design and t h e design t h e t u n n e l . I n short tunnels, t h e pavement l u m ina nce contribution from daylight penetration may enable sufficient d river a d a ption without s u pplementa l daytime l ig hting. Tunnels with wider portal designs and increased porta l heights have been identified as having i m p roved day l i g ht contri bution. (Refer to Section 14.3.1 .4 for additional daylig ht considerations for long tun nels.) criteria included in this chapter are based not only on theoretical considerations, but a lso on information Daylighting should be carefu lly considered for short d rawn from practical experience and engi neering tun nels where the fixation point may be in the center or judg ment. at the exit of the tunnel. I n many short tun nels, daytime l ig hting shou l d only be considered to supplem ent l i g ht i n g existing daylight penetration, in order to meet the recommendations i n t h e t u n n e l entrance zone and in L,h values req u i red where objects within the roadway The m aj o r factors affecting dayti m e its i nterior are discussed i n Sections 14.2.1, 14.2 .2, cha nge from being cast in positive contrast to negative 14.2 .3, and 14.3.1 . Due to the com plexity of the contrast due to the contri bution from the exit portal; conditions and the presence of other factors, such as objects may become invisible with i n this contrast surround conditions affecting dayl ight penetration for reversal zone. It is recommended that the l i g hting open road, u rban, or m o u ntain tunnels, it is impossible designer provide accu rate three-dimensional calcu lated to mathematica lly determine exact design l u m inance models to determ ine whether there is a ny under-lig hted va l ues in the threshold a n d i nterior zones. (Note: section of the tunnel. 14-9 ANSI/I ES RP-8-21, Recommended Practice: Lighting Roadway a nd Parking Facilities Field i nvestigations have shown that many short tunnels Annex C provides additional information on threshold with visible exit porta l s may have suitable daylight l ig hting. The l u minance val ues recommended in the pavement l u m ina nce to m i n im ize or even e l i m i nate a n nex may serve as the prel i minary design base val ues the need for the installation of supplem ental daytime for the tunnel threshold zones. Adjustments to these l ighting. va l ues, either up or down, are made by taking into consideration the factors outlined in Section 1 4.2 for the tunnel being designed. Table 14-2 summarizes these conditions and includes reco m mendations that w i l l affect t h resh old-zone 1 4.4.3 Nighttime Pavement Luminance. i l l u m i nation levels accord i ng ly. During nighttime, the motorist's eyes are adapted to a low exterior l u m i na n ce; therefore, a n i g httime average The a mbient l u m i nances of the su rfaces adjacent to pavement l u m i na nce of 2.5 cd/m2 is recommended for the tunnel portal within the visua l field are the most the entire length of a d ivided tunnel. (This l u m i na nce i mportant factors in determining the threshold-zone va lue has been derived by consensus among experts.) l u m i nance val ues. This section and Section 1 4.2.2 However, if the tunnel is undivided with bi-directional i l l u strate how these elements factor i nto the final design traffic, the light level should remain at daytime interior criteria and how they can significantly infl uence the levels to better assist the d river's vision in these hig her­ l ighting design. conflict scenarios. The a pproach and exit roadways Table 14-2. Adjustment Factors for Pavement Luminance in Threshold Zone (Lthl Tunnel Length Traffic Volume (AADT) Cyclists Exit Visible (from 1 SSD) Exit Not Visible (from 1 SSD) Daylight Penetration Daylight Penetration No Yes Present Wall Reflectance High High Low No Yes Wall Reflectance . Low High High Low . Low <25 m N.A. N .A. 0% (No Threshold Lighti n g Required) 0% (No Threshold Lighting Required) (<80 ft) 25 - 75 m (80 - 250 ft) 76 - 1 2S m (251 - 41 0 ft) < 1 5,000 >15,000 < 1 5,000 >15,000 No 0% 50% 50% 50% 50% 50% 1 00% 1 00% Yes 0% 50% 50% 1 00% 1 00% 1 00% 1 00% 1 00% No 50% 50% 50% 50% 1 00% 1 00% 1 00% 1 00% Yes 50% 50% 50% 1 00% 1 00% 1 00% 1 00% 1 00% No 50% 50% 50% 50% 50% 1 00% 1 00% 1 00% Yes 50% 50% 50% 1 00% 1 00% 1 00% 1 00% 1 00% No 50% 50% 1 00% 1 00% 1 00% 1 00% 1 00% 1 00% Yes 1 00% 1 00% 1 00% 1 00% 1 00% 1 00% 1 00% 1 00% >125 m All All 1 00% 1 00% (>410 ft) · Low Wa l l Reflectance: <30%. High Wa l l Reflectance: >30% Additional table notes: Single-direction tunnel: Supplemental daytime lighting is not needed within 7 m of the entry portal or within 15 m of the exit porta l. N i g htti me lighting is req u i red for the com p lete length of the tunnel. Bi-directional tunnel: Supplemental daytime lig hting is not needed with i n 7 m of both the entry and exit porta ls. N ighttime lighting is req u i red for the complete length of the tunnel. Source: Ada pted from CIE 88-2004, Figure 4.1 1 14-1 0 Tunnel Lighting sho u l d have a l u m inance level of no less than one-third Tu nnel maintenance (incl uding its frequency) sho u ld the tunnel interior level for one stopping sight d istance a l so be considered when targeti ng an i m p roved i l l u m inance va lue for a particular su rface. Some su rfaces, (SSD). such as shou lders, may a ccumulate prohibitive a mou nts 1 4.4.4 Non-roadway Surface Illumination. In general, i nterior su rfaces w
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