aashto gl-6 roadway lighting

8/15/2019 Aashto Gl-6 Roadway Lighting

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i

right American Association of State Highway and Transportation Officialsded by IHS under license with AASHTO Licensee=Aramco HQ/9980755100, User=Villa, Jose

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American Association of State Highw ay and Transportation Offic ials444 North Capitol Street, N W uite 249

Washington, DC 20001

www transportation.orgP: 02-624-5800, F: 202-624-5806 faX

O 2005 by the American Association of State H ighway and Transportation Officia ls.All rights reserved. Duplication is a violation of applicable law.

ISBN: 1-56051-325-X Publication Code: GL-6


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AASHTO 2004 2005 Executive Comm ittee

Voting Members

Officers:

President: Harold E. Linnenkohl, GeorgiaVice President: David Sprynczynatyk, North DakotaSecretary-Treasurer: Larry M. King, Pennsylvania

Regional Representatives:REGION I: Dan Tangherlini, District of Columbia, One-Year Term

Jim Capaldi, Rhode Island, Two-Year Term

REGION II: Harold Linnenkohl, Georgia, One-Year TermJoe M clnnes, Alabama, Two-Year Term

REGION III: Frank Busalacchi, Wisconsin, One-Year TermCarol Malnau, Minnesota, Two-Year Term

REGION IV: David Sprynczynatyk, North Dakota, One-Year TermVictor Mendez, Arizona, Two-Year Term

Nonvoting Members

Immediate Past President: Jack Lettiere, New JerseyAASHTO Executive Director: John Horsley, Washington, DC

...1ll



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Technical Com m ittee on Highway Ligh ting

Chairman: Karl A. Burkett, P.E., Texas

Secretary: Balu Ananthanarayanan, P.E., Wisconsin

Carl Andersen, FHWA

Stanley C. Biddick, P.E., Alabama

Mike DeAngelo, New Jersey

Jon Dickinson, Nevada

Ernest Kim, P.E., Oregon

Susan Lodahl, P.E., Minnesota

Jeff Unick, P.E., Pennsylvania

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AASHTO Highw ay Subcommitteeon Traffic Engineering

Chair: Delbert McOmieWyoming

MarylandVice Chair: Thomas Hicks

Liaison: Ken KobetskyAASHTO

Chair: Vacant

Secretary: Regina McElroyFHWA

State Member

Alabama

Alaska

Arizona

Arkansas

California

Colorado

Connecticut

Delaware

District of ColumbiaFlorida

Georgia

Hawaii

Idaho

Illinois

Indiana

Iowa

Kansas

Kentucky

Louisiana

Maine

Maryland

Massachusetts

Michigan

Timothy C. Taylor, P.E.

Kurtis J. Smith, P.E.

Mike Manthey, P.E.Richard C. Moeur, P.E.

Eric PhillipsTony Sullivan

Asif J. HaqKarla Sutliff

Gabriela Vidal

John F. Carey, P.E.

Donald D. Weber, P.E.

Douglas E. Noble, P.E.Lap Thong Hoang, P.E.

Keith Golden, P.E.

Alvin Takeshita

Lance Johnson

Joseph S Hill

Jim PoturalskiCarl T. Tuttle

Timothy D. Crouch

David A. Church, P.E.Kenneth F. Hurst, P.E.

Duane H. Thomas, P.E.

Charles Adams, P.E., PTOE

Bruce A. Ibarguen, III, P.E.

Thomas Hicks, P.E.

William Bent

Vacant

V




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Minnesota

Mississippi

Missouri

Montana

Nebraska

Nevada

New Hampshire

New Jersey

New Mexico

New York

North Carolina

North Dakota

OhioOklahoma

Oregon

Pennsylvania

Puerto Rico

Rhode Island

South Carolina

South Dakota

Tennessee

Texas

Utah

Vermont

Virginia

Washington

West Virginia

Wisconsin

Wyoming

Bernard J Arseneau

Wes Dean

Eileen Rackers

Duane Williams, P.E.

Randall D. Peters

Scott L. Thorson

William Lambert

Douglas R. BartlettTimothy J. Szwedo

Vacant

Bruce W. Smith, P.E.

J. Kevin Lacy, P.E., CPM

AI Covlin

Dave HolsteinHarold Smart

Edward L. Fischer, P.E., PTOE

Glenn Rowe

Samuel Forestier

Robert Rocchio, P.E.

Richard B. Werts

John Adler, P.E.

Don L. DahlingerGerald GregoryMichael L. Tugwell

Margaret (Meg) A. Moore

Robert E. Hull

Vacant

Raymond J. Khoury, P.E.

Theodore Trepanier, P.E.

Barry Warhoftig, P.E.

David I. Vieth

Michael N. Gostovich

Associate Member-Bridge, Port, and Toll

N.J. Turnpike Authority Robert F. Dale

Associate Member-Cities and Counties

City of Minneapolis Jon Wertjes

viright American Association of State Highway and Transportation Officialsded by IHS under license with AASHTO Licensee=Aramco HQ/9980755100, User=Villa, Jose


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Associate Member-Federal

USDA Forest Service John W. Bell

Associate Member-International

Manitoba Ben Rogers

Nova Scotia Ralph Hessian

Saskatchewan Sukhy Kent

viiright American Association of State Highway and Transportation Officialsded by IHS under license with AASHTO Licensee=Aramco HQ/9980755100, User=Villa, Jose


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AASHTO Hig hw ay Sub co mm ittee on Design

Chair: Allen D. BiehlerPennsylvania

FHWASecretary: Dwight A. Home

State Member

Alabama

Alaska

Arizona

Arkansas

California

Colorado

Connecticut

Delaware

District of Columbia

Florida

Georgia

Hawaii

Idaho

Illinois

Indiana

Iowa

Vice Chair: Robert L. WaltersArkansas

Liaison: Jim McDonnellAASHTO

Don T. Arkle, P.E.Steven E. Walker, P.E.

Gary Hogins, P.E.

Mary Viparina

Phillip L. McConnell, P.E.

Charles D. Clements, P.E.

Mark Leja, P.E.

Mithilesh “Mitch” KumarGary W . Meacham

Arthur W. GruhnMichael W. LonerganJames H. Norman

Michael H. SimmonsMichael F. BalbiererJames M. Satterfield

Kathleen PenneyZahra DorrizAllen Miller

Brian A. Blanchard, P.E.Robert GreerJim Mills, P.E.

James “Ben” Buchan, P.E.Babs Abubakari, P.E.Brent Story, P.E.

Gary C.P. ChoyJulius Fronda

Loren D. ThomasSteven C . Hutchinson

Michael Hine

Gary Mroczka, P.E.Jeff Clanton, P.E.

Michael J. KennerlyDavid L. LittleDeanna Maifield

viiiright American Association of State Highway and Transportation Officialsded by IHS under license with AASHTO Licensee=Aramco HQ/9980755100, User=Villa, Jose


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Kansas

Kentucky

Louisiana

Maine

Maryland

Massachusetts

Michigan

Minnesota

Mississippi

Missouri

Montana

Nebraska

Nevada

New Hampshire

New Jersey

New Mexico

New York

North Carolina

North Dakota

Ohio

James O .Brewer, P.E.Richard G. Adams, P.E.LaMonte C .Armstrong, P.E.

Kenneth Sperry, P.E.David Jones

N. Kent IsraelNicholas Kalivoda, IIILloyd E. Porta, Jr.

Jerome A. Casey, P.E.

Kirk G. McClellandRobert D. Douglass

John Blundo, P.E.Stanley Wood, Jr.

Mark A. Van Port Fleet, P.E.

Mukhtar Thakur P.E.

David FosterJohn B. Pickering, P.E.C . Keith Purvis, P.E.

David B. Nichols

Paul R. FerryLesly Tribelhom

Don TurekDawn AllynJames J. Knott

Frank Csiga, Jr., P.E.Ruedy Edgington

Rand Pollard, P.E.Paul K. Sinnott, P.E.

Craig A. Green

Kiran B. Pate1Brian Strizki

Roy Maestas, P.E.Dennis Peralta, P.E.Max E. Valeno, P.E.

Philip J. Clark, P.E.Daniel D’Angelo, P.E.Richard W. Lee, P.E.

Jay A. Bennett, P.E.Deborah M. BarbourArt McMillan

Mark Gaydos

Cash Mise1Dirk GrossTimothy McDonald

ix




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Oklahoma

Oregon

Pennsylvania

Puerto Rico

Rhode Island

South Carolina

South Dakota

Tennessee

TexasUtah

Vermont

Virginia

Washington

West Virginia

Wisconsin

Wyoming

Christine M. Senkowski, P.E.Bruce E. Taylor

Thomas Lauer

Dean A . Schreiber, P.E.Brian D. Hare, P.E.

Ariel PérezJosé E. Santana-Pimente1

J. Michael Bennett, P.E.

Robert I. Pratt, P.E.Rocque L. Kneece, P.E.John V. Walsh, P.E.

Joel GenglerJoe J. Feller

Jeff C. JonesMark Holloran

Mark A. MarekStan Burns, P.E.

Kevin Marshia, P.E.

Mohammad Mirshahi, P.E.Barton A. Thrasher, P.E.

Harold Peterfeso, P.E.Richard Albin, P.E.Ken L. Smith, P.E., CVS

Jason C. FosterRandolph T. Epperly, Jr.

Beth Cannestra

Paul P. BercichTony Laird

U.S. DOT Member

FAA Rick Marinelli, P.E.

Associate Member-Bridge, Port and Toll

N.J. Turnpike Authority

Penn. TurnpikeCommission

Associate Member-Bridge, Port and Toll

Port Authority of NY and NJ

Associate Member-Cities and Counties

City of Minneapolis Fred Abadi

J Lawrence Williams

Barry L. Troup, P.E.

Scott D. Murre11

Xright American Association of State Highway and Transportation Officialsded by IHS under license with AASHTO Licensee=Aramco HQ/9980755100, User=Villa, Jose


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Associate Member-Federal

USDA Forest Service Ellen G. LaFayette

Associate Member-International

AlbertaBritish ColumbiaOntarioOntarioSaskatchewan

Allan KwanRichard VoyerJoe BucikJoe BucikSukhy Kent

xiright American Association of State Highway and Transportation Officialsded by IHS under license with AASHTO Licensee=Aramco HQ/9980755100, User=Villa, Jose



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Table of Contents

Cha pter 1:

Chap ter 2:

Chapter 3:

Introduction ................................................................................................................ 1Overview ...................................................................................................................... 1Need for Engineering Expertise ................................................................................... 1Necessary Expertise ..................................................................................................... 1

Modern Controls and Master Lighting Plans ............................................................... 2Recommended Design Methods .................................................................................. 2

2.1

2.2

2.3

2.4

2.5

2.6

Master Lighting Plans ................................................................................................ 3Overview ........................................................................................................... 3Introduction ....................................................................................................... 3Definition ........................................................................................................... 3Benefits .............................................................................................................. 3Plan Development ............................................................................................. 3Introduction ....................................................................................................... 3

Participants ........................................................................................................ 4Groups Having Concerns About Lighting ......................................................... 4

Goals of a Maste r Lighting Plan ........................................................................ 5Introduction ....................................................................................................... 5Improved Safety ................................................................................................ 5Environmentally Judicious Use of Resources ................................................... 5Energy Use ........................................................................................................ 6Tourists, Businesses. and Nighttime Activities ................................................. 6Planned Maintenance ........................................................................................ 6Lighting Curfews ............................................................................................... 6Introduction ....................................................................................................... 6

Considerations Before Implementation ............................................................ 7Electrical and Lighting Management Systems .................................................. 8Introduction ....................................................................................................... 8Cost .................................................................................................................... 8Benefits .............................................................................................................. 9Benefits of ELMS Standardization ................................................................. 10Conducting Studies .......................................................................................... 10Introduction ..................................................................................................... 10Electrical System ............................................................................................. 11Benefits and Effects of Curfews and Dimming ............................................... 11Traffic Studies ................................................................................................. 11Community Goals ........................................................................................... 11

Reasons for Curfews ......................................................................................... 7

Budget ............................................................................................................. 11

Techniques of Lighting Design ................................................................................ 133.1 Overview ......................................................................................................... 13

Introduction ..................................................................................................... 13Level and Uniformity of Illuminance and Luminance .................................... 13Illuminance Considerations ............................................................................. 14

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Roadway Lighting Design Guide

3.2

3.3

3.4

3.5

3.6

Luminance Considerations .............................................................................. 14Visibility-Based Design Methods .................................................................... 16

General ............................................................................................................. 17Benefits of Lighting ......................................................................................... 17Rural Interchanges ........................................................................................... 17Warranting Conditions ..................................................................................... 17Continuous Freeway Lighting ......................................................................... 18Partial Interchange Lighting ............................................................................ 19Special Considerations ..................................................................................... 20Bridges ............................................................................................................. 20Design Values for Freeways ............................................................................ 20General ............................................................................................................. 20Design Considerations ..................................................................................... 20Lighting Levels on Crossroads ........................................................................ 20Partial Interchange Lighting ............................................................................ 21Adaptation (Transition) Lighting ..................................................................... 22

Bridges and Overpasses ................................................................................... 22Other Considerations ....................................................................................... 22Area Classifications ......................................................................................... 22

(Including Walkways and Bicycle Ways) ....................................................... 23General ............................................................................................................. 23

Lighting Design Levels .................................................................................... 23Other Considerations ....................................................................................... 23Pole Placement Guidelines .............................................................................. 26Introduction ...................................................................................................... 26

Obstruction of View ........................................................................................ 26Height Restrictions .......................................................................................... 26Medians ........................................................................................................... 26Gore Areas ....................................................................................................... 26Maintenance Considerations ............................................................................ 26Adjacent to Deflecting Barriers ....................................................................... 27General Safety Concerns ................................................................................. 27Design Options ................................................................................................ 27

Option 1: Remove the Obstacle ................................................................. 27Option 2: Redesign the Obstacle ............................................................... 27Option 3: Relocate the Obstacle ................................................................ 28Option 4: Use Appropriate Breakaway Device ......................................... 28

Option 6: Delineate the Obstac le ............................................................... 29References ........................................................................................................ 29

. .Warranting Conditions ..................................................................................... 17

. .

Streets and Highways Other Than Freeways

. .Warranting Conditions ..................................................................................... 23

Option 5: Shield the Obstacle .................................................................... 29

Chapter 4:

Chapter 5:

Techniques of Lighting D esign ................................................................................ 31Tunnels and Underpasses ........................................................................................ 335.1 Overview ......................................................................................................... 33

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Chapter 6:

Chapter 7:

Chapter 8:

Chapter 9:

5.2

5.3

5.4

Underpasses ..................................................................................................... 33

Warrants for Nighttime Underpass Lighting ................................................... 33

Selection and Placement of Underpass Luminaires ........................................ 34Vehicular Tunnels ........................................................................................... 34

Short Tunnels .................................................................................................. 35Long Tunnels ................................................................................................... 35Warrants for Tunnel Lighting .......................................................................... 35Visibility Optimization of the Tunnel and Approach Features ....................... 36Daytime Lighting of Tunnel Interiors ............................................................. 37

General Scope and Guide Application ............................................................ 33

Design Values for Underpass Lighting ........................................................... 34

Genera l Scope and Guide Application ............................................................ 34

Short Tunnels-Silhouette Visibility .............................................................. 37Entrance Portal Lighting ................................................................................. 37Lighting Beyond the Entrance Zone ............................................................... 37Nighttime Tunnel Lighting .............................................................................. 38

Tunnel Lighting Control Systems ................................................................... 38Maintenance Factor for Tunnel Lighting Design ............................................ 38

Selection and Placement of Tunnel Luminaires .............................................. 38

Work Zone Lighting and Temporary Roadway Lighting .................................... 39Introduction ................................................................................................................ 39cos t ............................................................................................................................ 39Types .......................................................................................................................... 39Design Values ............................................................................................................ 39Safety .......................................................................................................................... 39Work Area Lighting ................................................................................................... 40

Roundabouts ............................................................................................................. 41Introduction ................................................................................................................ 41Warrant Conditions ..................................................................................................... 41Recommended Lighting Level ................................................................................... 41

Electrical Systems Req uirements ............................................................................ 43Disconnects ................................................................................................................. 43Guidelines Available .................................................................................................. 43Grounding ................................................................................................................... 43Voltage Drop .............................................................................................................. 43

Safety Rest Areas ...................................................................................................... 45Overview ......................................................................................................... 45Warrant ............................................................................................................ 45Design Values .................................................................................................. 45Entrance and Exit ............................................................................................ 45

Parking Areas .................................................................................................. 47Activity Areas .................................................................................................. 47Main Lanes ...................................................................................................... 47

Interior Roadways ........................................................................................... 46

xv



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Chap ter 10: Roadway Sign Lighting .......................................................................................... 4910.1

10.2

10.3

10.4

10.5

Overview ..................................................................................................... 49Introduction ................................................................................................. 49Key Elements of Roadway Sign Lighting ................................................... 49Sign Lighting Warrants ............................................................................... 50Illuminated Sign Types ............................................................................... 51Ambient Luminance Classifications ........................................................... 51

Sign Lighting Recommendations ................................................................ 52Lighting Uniformity .................................................................................... 53Sign Color Standards .................................................................................. 53Placement of Lighting Units ....................................................................... 53References ................................................................................................... 54

. .

Chap ter 11: Ma intenance Considerations in Roadway Lighting Design ............................... 55General ...................................................................................................................... 55Maintenance Factors ................................................................................................. 55Luminaire Dirt Depreciation (LDD) ......................................................................... 55Lamp Lumen Depreciation (LLD) ............................................................................ 55Equipment Factor (EF) ............................................................................................. 56Support Structure Maintenance ................................................................................ 56Electrical Distribution and Control System Maintenance ........................................ 56External Factors ........................................................................................................ 57

Chapter 12: Sky G low and Light Trespass ............................................................................... 5912.1 Overview ..................................................................................................... 59

Introduction ................................................................................................. 59Types of Objectionable Roadway Lighting ................................................ 59

12.2 Mitigating Sky Glow and Light Trespass ................................................... 60

Glossary ........................................................................................................................................... 61

xviright American Association of State Highway and Transportation Officialsded by IHS under license with AASHTO Licensee=Aramco HQ/9980755100, User=Villa, Jose



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Chapter 1Introduction

Overview

This guide replaces the 1984 publication entitled, An Informational Guide fo r R oadway Lighting.Ithas been revised and brought up to date to reflect current practices in roadway lighting. The guide pro-vides a general overview of lighting systems from the point of view of the transportation departments andrecommends minimum levels of quality. The guide incorporates the illuminance and luminance designmethods, but does not include the small target visibility (STV) method.

Two appendices to this document are located online for reference purposes at http://downloads.trans-portation.orgAighting.pdf. Appendix A is entitled Literature Review and References,and contains infor-mation on research studies related to accidents and highway lighting, driver parameters, pavementparameters, and a summary of further references. Appendix B contains an overview of Lighting Basics,including background information on the various issues related to effective highway lighting.

Need for Engineering Expertise

Most states require that final design documents be signed and sealed by a registered professional engi-neer. The registrant is normally required to only sign and seal documents that the registrant prepared, ordocuments for which the registrant was responsible for the direction and control of the work. Documentsinclude specifications, reports, drawings, plans, design information, and calculations. Lighting designs,

as described in this guide, meet the criteria for requirement of an engineering seal. This is necessarybecause the public interest is at stake. In addition, the designs integrated with other aspects of the trans-portation facility that have engineering features. These other aspects include support structures, break-away devices, pavement characteristics, electrical characteristics, traffic engineering features, trafficmanagement features, and the relative priority of lighting with respect to other safety features on the facil-ity. Proper engineering udgment must be used in the integration of the various aspects of the facility, aswell as in the consideration of maintenance and life-cycle costs.

Many of the current problems in outdoor lighting are due to poor lighting designs. These problemsinclude less than optimal benefits from the lighting systems, excessive glare and visual clutter at night, theuse of improper deprecation factors and photometric distributions, excessive sky glow and light trespass,and excessive maintenance and energy costs. The primary cause of poor lighting designs is a lack ofproper lighting and electrical education.

Necessary Expertise

Departments of transportation (DOTS) hat hire consultant engineers are paying for engineering exper-tise. This expertise is available in the area of roadway lighting and associated electrical systems. Theexpertise required for DOT lighting designs includes:

lamp types and characteristics, ncluding depreciation factorsballast types and characteristicsfixture mechanical characteristics

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lens typesphotometric performance of luminaires and factors impacting such performancefixture mounting typespole mechanical and electrical characteristicsbreakaway device options and when appropriate to useclear zone criteriapole types, mounting options, and loading considerationsfoundation and support detailspavement reflection factorsmounting height and spacing optionslight trespass and sky glow issues including laws and ordinanceslighting quality requirements, such as i lluminance, luminance, veiling luminance, and visibility. aintenance considerations for individual components and the lighting system as a wholeenergy and life-cycle costscoordination with master lighting plans.

Consultants accepting payment for lighting system design should perform that work in an engineeringmanner. This includes exercising engineering judgement when balancing all of the above characteristics.Training courses are available for engineers wishing to learn how to design lighting systems.

Recommended Design Methods

This guide recommends only the luminance and illuminance design methods but recognizes efforts toturn lighting designs toward visibility-based design methods. A discussion of visibility-based methods isincluded. The fact that this guide does not recommend the small target visibility (STV) design methodshould not be interpreted as non-support for visibility based methods and associated research. The STVmethod is not recommended as standard practice because the increased benefits of using this designmethod have not been adequately demonstrated and confidence in the ability to achieve design values andbetter visibility is low. Accurate visibility calculations require the input of all light sources, including off-roadway sources and headlamps from multiple vehicles. Such data are not easily obtained on roadwaysunder even moderate traffic conditions. The fact that lighting is installed on roadways based on, amongother things, high traffic volumes lends further uncertainty to the value of visibility calculations. STV orother visibility criteria may be applied as an additional quality criteria in order to gain experience withthose methods and to determine the value of such criteria.

Modern Controls and Master Lighting Plans

This guide also addresses modern control methods for lighting systems and encourages the use of amaster lighting plan incorporated into the traffic management centers, emergency management centers,or other central locations. Better use of resources can be achieved through innovative strategies such as

lighting curfews, special event and weather situation control, and maintenance automation. Curfews cancreate energy savings. Energy cost savings on one particular lighting system may allow additional light-ing systems to be instal led and operated in peak traffic times, thereby improving safety of the entire areaunder the jurisdiction of the master lighting plan.

Maintenance inventory and management can be improved by remotely monitoring percentage of lightsburning, diagnosing problems prior to sending out maintenance crews, tracking life-cycle costs, and mon-itoring the performance level of maintenance contractors.

2right American Association of State Highway and Transportation Officialsded by IHS under license with AASHTO Licensee=Aramco HQ/9980755100, User=Villa, Jose



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TABLE 2 1. Master Lighting Plan Development Process

SteplAction~~~~~

1. Coordinate with other participants to set goals.

2. Consult with and consider the concerns ofvarious groups having a stake in publiclighting.

3. Conduct a study to justify and determine thefeasibility of the planned strategies.

More Information

See following heading for information on participants.See Section 2.3 for information on goals.

See “Groups Having Concerns About Lighting”later in this section.

See Section 2.3 for details on lighting curfews.See Section 2.4 for details on electrical and lightingmanagement systems.See Section 2.5 for details on conducting studies.

Participants

The master lighting plan approach is a regional concept that could involve the following entities:

the state DOT9 city

county9 police

traffic management centers, emergency management centers, or other central locationsfire, EMS, and other emergency agenciestunnel operatorschambers of commerce (event coordination)parks (bike and pedestrian trails, fireworks, sports fields, etc.)the Federal Aviation Administration (near airports)

the Coast Guard (near waterways)Coordination Needed. Officials of these organizations can coordinate all publicly owned lighting sys-

tems by setting joint goals and laying out plans to achieve those goals. A master lighting plan should beseen as a component of city management.

Groups Having Concerns About Lighting

In addition to the participating entities, other groups may have concerns related to public lighting, andtheir concerns should be considered. These groups may include:

citizens and property owners

retailers and other businesstouristsvisitorsparks and sports facilities (including spectator sports and participant sports such as driving rangesand softball)



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Master Lighting Plans

2.3 GOALS OF A MASTER LIGHTING PLAN

Introduction

A master lighting plan should have five major goals:

improved safety

environmentally judicious use of resourcesjudicious energy useattracting tourists, businesses, and nighttime activitiesplanned maintenance.

Discussions of each of these goals follow under separate headings.

Improved Safety

Improved safety is the primary goal of public lighting. Public lighting affects motorists, cyclists, andpedestrians. Public lighting includes roadways, sidewalks, and signs. A master lighting plan can helpmaximize available resources and increasing management coordination. Maximizing resources meanslowering the operating costs of existing and new lighting systems, which may allow the installation andoperation of more lighting systems that operate only when needed.

Environmentally Judicious Use of Resources

“Environmentally judicious use of resources” refers to the consideration of safety, security, aestheticand architectural compatibility, creature comfort, sky glow, light trespass, glare, and visual clut ter.

Consideration should be given to the desires of the facility owner, city officials, and citizens asexpressed in public hearings, local laws and ordinances, and other sources.

All outdoor lighting creates some degree of sky glow and light trespass. Modem controls can imple-ment switching or dimming curfews that better address the needs and desires of the community (seeSection 2.4 for more information). In short, all community and business desires should be respected, andcompeting concerns should be balanced as much as possible.

A wide variety of alternatives are available for outdoor lighting. Various environmental factors shouldbe subjectively weighted for different situations. Some factors to consider include:

purpose of the lightingsource typedegree of light cutofflight levelmounting heightambient light levels (other lighting in the area)historical considerations

area land useroadway classificationpedestrian and cyclist useimplementation of lighting curfews (see Section 2.4)effect on wildlife (some studies show that nighttime lighting may affect wildlife)

A review of the following facility types should demonstrate an ntuitive weighting:

urban freewaysrural freewayscentral business district CBD)

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Organization

arterial roadwayscollector roadwaysresidential streetsparklands and campgrounds

Various guidelines of national and international lighting engineering and architectural groups may beconsulted for reasonable limits and strategies to optimize lighting designs limiting negative effects. The

following table shows some of these groups.

Internet Address

The International Commission on Illumination (CIE)

The Illuminating Engineering Society of North America (IESNA)

The European Committee for Standardization (CEN)

http: lwww.cie.co.at/cie

http://www.iesna.org

http://www.cenorm.be

Energy Use

Important factors affecting energy use include light levels, lamp type, ballast type, and electrical sys-tems quality. Lighting curfews can also help conserve energy (see Section 2.4 for more information).

Tourists, Businesses, and Nighttime Activities

Public lighting intended to attract tourists, CBD businesses, and nighttime activities may includepedestrian, building façade, bridge or structure, landscape, and sign lighting. The intent is to provide apleasing and attractive environment for nighttime activities.

Planned Maintenance

The purpose of planned maintenance is to prioritize maintenance schedules, organize contracts, anddetermine acceptable levels of service. Planned maintenance establishes consistent replacement products,coordinates traffic control setups, enhances the use of electronic monitoring, takes advantage of modeminventory systems, reduces trouble-shooting of problems, reduces electrical hazards, which can lower over-all costs. Larger systems are more likely to have a lighting engineer available to oversee the total processof design, installation, and maintenance, thereby allowing for replacement fixtures with suitable photo-metric, electrical performance, and aesthetic features. Under a master lighting plan, life-cycle costs, lifeexpectancy, and quality studies are enhanced, and the region may have more buying clout. See Section 2.5for a discussion of how modern electrical and lighting management systems can help with maintenance.

2.4 LIGHTING CURFEWS

Introduction

Curfews for lighting involve the use of modem controls to turn off or dim selected parts of lightingsystems as permitted by reduced traffic flow, favorable weather conditions, and other local conditions.Lighting curfews represent the active “operation” of the system, allowing for energy savings, greaterflexibility in resource allocation, and reduction of light-trespass. However, officials implementing suchoptions should be aware of consequences and conduct meaningful studies of costs and benefits.



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Master Liahtinn Plans

Studies on the effectiveness of roadway lighting have mixed results. Generally, continuous lighting maybe expected to reduce nighttime crashes by about 30 percent. The precise mechanism for the reduction ofthose crashes is not known. Currently it is not possible to translate surrogate measures, driver performancewith targets, or other measures directly into a safety change.

Motor vehicle crash data for 1998 from the National Highway Traffic Safety Administration’s FatalityAnalysis Reporting System (FARS) and the General Estimates System GES) show that 90 percent offatal and injury crashes that occur on the roadway, where lighting guidelines specify that light be placed,are multiple vehicle crashes. The number of overall crashes tapers off substantially after midnight onweekdays and after 4:OOa.m. on weekends. At these late hours, most of the crashes are single vehicle, off-roadway crashes for which lighting may not be likely to help, except possibly at decision-making pointssuch as ramp gores, intersections, and merge areas.

Warrants for lighting are empirically derived and based, among other things, on trafñc volume. For light-ing that has been installed based on trafñc volumes, it may be reasonable to cut back the operation of the light-ing system to complete interchange lighting or to partial interchange lighting when traffic volumes subside.

Studies show that crash rates increase where systems are turned off or where every other luminaire isturned off. Alternate luminaire operation results in poor uniformity ratios. The issue of driver needs and safetyversus conservation efforts should be closely examined when considering curfews. Poorly conceived conser-vation efforts may contribute to increases in trafñc crashes and operational problems. These problems may

actually result in higher overall costs.

Reasons for Curfews

Government entities around the world are considering lighting curfews for the following reasons:

Low late-hours traffic volum es.AASHTO warrants for highway lighting are based, among otherthings, on traffic volume. When the primary reason that lighting is (or was) installed was due to hightraffic volumes and high usage, which drops off in later hours of the night, it is reasonable to turn offor reduce the lighting after such drop-offs.Freeing resources for greater overall safety. Lowering the operational costs of lighting systems byreducing electrical and maintenance costs through curfews may allow more lighting systems or othercrash countermeasures to be installed, thereby reducing the overall nighttime crash rate within thejurisdiction of the master lighting plan.Technology now practic al. Modem control technology now allows control of individual luminairesor systems of luminaires at reasonable costs.Positive study results. Recent studies show that light dimming and turn-off curfews are viableoptions for the management of public lighting systems, including roadway lighting. Although paststudies showed unfavorable increases in traffic crash rates because of turning off lighting, these stud-ies were performed on systems where the lighting was turned off or partially turned off for the entirenighttime period.Energy savings. Energy costs can be high.Sky glow issues.Sky glow issues are of increasing importance (see Chapter 12).

Considerations Before Implementation

Special events, maintenance or construction activities, weather, and other local considerations shouldbe included in the decision to implement lighting curfews. Implementation of curfews should occurthrough traffic management centers or other central locations and should be monitored to gain experienceas to the best operational procedures.

The following excerpts are from the FHWA report Reduced Lighting During Periods of Low Traf icDensity FHWA/RD-86/018). When considering lighting curfews, the complete report should be read,while realizing that it is dated August 1985. Modem crash data should be analyzed.



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In part, this report states, over 50 percent of all motor vehicle fatalities occur in darkness eventhough only 25 percent of all travel occurs at night. This over representation has been used as a jus-tification for installing fixed roadway lighting on many highways. However, research that hasattempted to determine the effect of such fixed lighting on frequency and severity of night accidentsappears to be mixed, such frequencies and severities being dependent on a host of geometric andtraffic factors including the volume of traffic utilizing the road, how such volume is related to theroad’s capacity, and the complexity of the driver’s visual search task.

During the past decade, several highway agencies have switched off roadway lighting duringperiods of energy shortages to reduce maintenance and operating costs. However, quite often suchlighting was restored when nighttime accidents increased. One fundamental problem with theselight reduction techniques was that lighting was reduced or eliminated during the entire nighttimeperiod, rather than only when traffic volume was low.

By providing full lighting during periods when volumes are high and the roadway operates nearcapacity and providing reduced lighting as the traffic decreases, the potential exists for realizing con-siderable energy savings while still providing the benefits of full lighting at locations (e.g., inter-changes) and at times e., high volumes) where driver decision-making is the most critical and thegreatest visibility is required.

From a safety standpoint there is a definite reduction in (simulated) hazard detection perfor-

mance, which theoretically implies some reduction in safety. This implied reduction in safety is sta-tistically significant for all off and one side only lighting tactics, but not statistically significant forthe dimmed tactics and the every other off tactic. Unfortunately, it is not possible at this time to quan-tify the exact decrease in safety in terms of the frequency of nighttime accidents, the night accidentrate, or the night-to day accident ratio. Only an evaluation of long term installations can address thisissue (see following discussion of further research needs).

Reduced freeway lighting tactics normally should not be implemented before about 11:OO p.m.in most urban areas, since traffic density typically remains relatively high until that time. Regularlyscheduled sports events and other large traffic generators could change this time to a later hour,while cities with little or no evening activity might allow an earlier light reduction.

2.5 ELECTRICAL AND LIGHTING MANAGEMENT SYSTEMS

Introduction

Master lighting plans allow for benefits to be derived from modem electronic monitoring and controlsystems known as electrical and lighting management systems (ELMS). This technology can detect light-ing problems more quickly and accurately than traditional methods. The maximum benefit is most likelyrealized when the technology is applied across the entire lighting infrastructure within a local authority’sinventory. Remote monitoring technology can modernize the management, operation, and maintenance ofthe street lighting infrastructure.

cost

The costs of introducing the technology are difficult to est imate without significant evaluation. Thishas led to concerns over initial investment costs, running costs, and anticipated payback on investment. Itis important that evaluations consider a whole system approach. Remote monitoring can be progressivelyused and specified for new lighting schemes and for installations requiring additional or extraordinarymonitoring and control.



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Master Liahtina Plans

Benefit

Benefits

The benefits of ELMS are outlined in the following table.

Benefits of ELMS

Explanation

Improved electrical safety and reliability

More efficient contract management

ELMS provides for ground fault detection and notifi-cation of system malfunction.

Contracts can be written to pay for maintenance by themonth instead of by each part repaired or replaced.Percent of luminaires burning can be verified electroni-cally through ELMS, thus reducing survey costs.

Energy savings Energy saving lighting curfews are facilitated throughremote or automatic control of lighting systems.

~~ ~

Reduced maintenance costs ELMS facilitates advance knowledge of problems,parts needed, and types of personnel needed. Thisresults in better overall contractor information andsupervision of maintenance work.

Reduced life-cycle costs ELMS can provide the information and documenta-tion needed to write specifications and modifyapproved products lists, thus lowering maintenancecosts and improving reliability.

The recent avalanche of technical advances is about to bring a wave of new technologies to organiza-tions that operate and maintain street lighting systems. These technologies have the potential to improve

service quality, lower maintenance costs, increase productivity, and conserve energy. But the implemen-tation of new technologies also holds risk because of technical and commercial complexities. The key toreducing this risk is to make the new technologies compatible with existing systems, and to ensure thatthe systems of different suppliers are interoperable.

Master lighting plans and ELMS allow coordination, through the traffic management centers, of allinterested subjects and parties including cities, department of transportation personnel, police, specialevents, traffic management, state and local ordinances, landscape lighting, landscape installation (espe-cially trees), landscape maintenance, pedestrians, cyclists, and central business district interests.

9right American Association of State Highway and Transportation Officialsd d b IHS d li ith AASHTO Li A HQ/9980755100 U Vill J

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Benefits of ELMSStandardization

Interoperability and compatibility standards for ELMS results in four significant benefits, as outlinedin the following table.

Benefits of ELMSStandardization

Benefit

Reduction in the complexity of integratingsystems

~

Creation of more open and competitive market

Allowance for the mixing of systems fromdifferent suppliers

Evolution through open participation in whichall views are considered

Explanation

This translates into lower risk of implementationdelays and fewer resources required for system instal-lation and introduction.

Proprietary technologies tend to lock buyers into sin-gle-source supply arrangements. Such arrangementsgive the incumbent supplier undue leverage in futurepurchases and make substitution of non-performingsuppliers expensive. Standardization discourages this

tendency.Various systems have their own strengths and weak-nesses, given the differing situations in which theyare used. If a buyer wishes to implement a systemwith “best of breed” components, then interoperationand compatibility between these components makethat possible.

Due process through a public forum ensures validationand utility of the underlying technologies.

Interoperability and compatibility standards lead to a more competitive environment for suppliers.However, suppliers benefit from standards as well. In general, buyers are suspicious of single-sourcemarket conditions, and therefore simply delay purchases until a competitive environment has evolved.History has shown that the establishment of standards accelerates adoption of new technologies andcauses the market to expand more rapidly.

2.6 CONDUCTING STUDIES

Introduction

Before developing a master lighting plan, a study should be conducted by traffic and lighting engi-

neers. The study is needed for the following reasons:to determine how the various lighting systems can best be optimized and coordinatedto justify the implementation of lighting curfewsto justify expenditures for technological improvements such as ELMS.

This section describes the recommended scope of such a study. Generally, the study should cover thefollowing items:

electrical systempurpose of the lighting systembenefits and effects of curfews and dimmingtraffic studies

10right American Association of State Highway and Transportation Officialsded by IHS under license with AASHTO Licensee=Aramco HQ/9980755100 User=Villa Jose

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Master Lighting Plans

surrounding land use and surrounding lightingsecurity concernssky glow and light trespass issuescommunity goalscoordination with navigation authoritiestraffic management interaction

controlscurfew monitoringELMS Implementationcoordination with roadway maintenance and construction activitiesbudget.

These items are discussed in this chapter and following chapters under separate headings.

Electrical System

The study should evaluate electrical energy use and potential for savings.

Benefits and Effects of Curfews and Dimming

Dimming should be considered if light levels are higher than those required by AASHTO. In someinstances lighting is installed at levels higher than the minimum required because of safety or work zones.It may be reasonable to dim this to only the required level after heavy traffic subsides. The same logic canbe applied to dimming as is applied to curfews.

Traffic Studies

Assess the hourly nighttime traffic volumes and crashes. Consider reducing continuous lighting to par-

tial interchange lighting at the point during the nighttime hours when fatal crashes, analyzed over a three-year period, is found to drop to half of the peak rate. Consideration may be given to the type of crashesand a study to determine if lighting is a factor in the specific traffic safety problem.

Community Goals

Conduct a survey of community goals for lighting.

Budget

Consider how the master lighting plan relates to the following budgetary factors:

How will the plan affect the budget for lighting installation and maintenance?How will the plan affect the budget and methods for other traffic safety devices?What is the budget for installing controls?


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Chapter 3Techniques of Lighting Design

3.1 OVERVIEW

Introduction

Industry development and general experience on lighting of roadways has resulted in a reasonablywell-developed technique for the design of lighting systems. Accepted methods exist for achieving agiven lighting condition known as either level of illuminance or level of luminance. These methods per-mit ready analysis of alternative lamps, luminaires, mounting height, luminaire spacing, energy con-sumption, etc., to determine a preferred design. As more efficient light sources and better luminaires aredeveloped, they are incorporated into current designs.

The design of a roadway lighting installation is a process of applying known or specified photomet-ric characteristics of selected lamp-luminaire combinations. Since illuminance considers only incidentlight, photometric information about the luminaire and proximity and orientation to the pavement sur-face is the only required information. To achieve the desired luminance, pavement reflectance should beknown. A trial-and-adjust process of assumed luminaire locations is used in making calculations ofeither the average amount of illuminance or the average luminance over the roadway. For each lamp-luminaire combination, the manufacturers’ data will show photometric performance of luminaires. Thesedata can be used, along with pavement reflectance characteristics in the case of luminance, to theoreti-cally determine luminaire positions to produce the desired luminance over the given pavement area. It isimportant to test luminaires to determine that luminaires supplied match the photometric performance of

luminaires used in the design process. Experience has shown that disregard for testing has yielded dis-appointing results.

Calculations are performed by computer programs designed for lighting design purposes. The valuesof the average amount of illuminance or luminance and variations in the average level are the basis ofdesign.

Level and Uniformity of Illuminance and Luminance

The level and uniformity of illuminance or luminance along a highway depends on several factors,including the lumen output of the light source, luminaire distribution, mounting height, luminaire posi-tion, pavement reflectance, and spacing and arrangement. The same average level can be obtained by dif-ferent installation arrangements, such as a few high-output light sources or a greater number oflow-output sources. A concern in comparing of such alternate systems is the uniformity of illuminance orluminance over the traveled way to be lighted.

Luminaires are available in a wide range of types, sizes, and photometric outputs. Lighting systemsusing high-efficacy and large-lumen lamps can be designed to provide a satisfactory level and unifor-mity of illuminance or luminance. Higher luminaire mounting heights offer a number of advantages andshould have full consideration when selecting design criteria. All appropriate light sources should beconsidered, and the size or sizes that will give the most effective and economical lighting system shouldbe used.

13right American Association of State Highway and Transportation Officialsd d b IHS d li i h AASHTO Li A HQ/9980755100 U Vill J

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Illuminance Considerations

Illuminance in roadway lighting is a measure of the light incident on the pavement surface. It is mea-sured in foot-candles (Lux). Illuminance and luminance values are empirically derived from many yearsof experience. Illuminance design may be accomplished with lighting design software or with iso-foot-candle templates. The illuminance at any certain point will be the sum of illuminance from one or severalcontributing sources.

Luminance Considerations

Luminance in roadway lighting is a measure of the reflected light from the pavement surface that isvisible to the motorist’s eye.

Pavemen t Reflectance Important. In addition to knowing the posit ion, distribution, and intensity ofthe luminaire, the calculation of luminance requires a knowledge of the reflectance characteristics of thepavement and the location of the observer. See Fig. 3-1.

A system of pavement reflectance values used since 1970 by C.I.E. and adopted by ANSUESNAdivides the reflectance characteristics of pavements into four categories: R1, R2, R3, and R4. (Tables A3-A6 CIE 132-1999 and Tables Al-A4 ANSI/IESNA RP-8-00). Each category has its own table of valuesof reflectance for specified angles and are commonly known as r-tables. The r-tables have been adoptedfor the purpose of this guide. Road surface classifications are described in Table 3-1. When designing aroadway lighting system using these classifications, he final type of road surface in place, when the light-ing system is operative is usually selected. (See the online Literature Review at httu://downloads.trans-portation.ordiighting.pdf for more information on pavement reflectance).

A calculation of reflected light toward the eye of the observer is made for each roadway point 83 mfrom the observer, summing the luminance from each luminaire.

Figure 3 1. Calculation points for luminance and illuminance design methods.



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Techniques of Lighting Design

TABLE3 1. Road Surface Classifications

Class

R1

R2

R3

R4

QO

0.10

0.07

0.07

0.08

Description

Portland cement concrete road surface. Asphaltroad surface with a minimum of 12 percent of theaggregates composed of artificial brightener(e.g., Synopai) aggregates (e.g., labradorite, quartzite).

Asphalt road surface with an aggregate composedof minimum 60 percent gravel [size greater than1 cm 0.4 in.)].Asphalt road surface with 10 to 15 percent artificialbrightener in aggregate mix. (Not normally used inNorth America).

Asphalt road surface (regular and carpet seal) withdark aggregates (e.g., trap rock, blast furnace slag);rough texture after some months of use (typical

highways).~

Asphalt road surface with very smooth texture.

Mode of Reflectance

Mostly diffuse

Mixed (diffuse andspecular)

Slightly specular

Mostly specular

*Q, = representative mean luminance coefficient.Reprinted fromAmerican Na tional Standard Practice fo r Roadway Lighting,A N S U E S RP-8-00, IlluminatingEngineering Societyof North America. Used by permission.

The observer moves with points. For example:

The calculation for point A, is made from observer position A,.The calculation for point Bp is made from observer position Bo, same one quarter lane line.The calculation for point C, is made from observer position Co, lane 4.

The number of points to be considered is calculated as follows:

Number of PointsLuminaire C ycle Distance

10

The distance between points should not exceed 15 feet 5 m). Calculations should include a minimumof three luminaire cycles downstream and one luminaire cycle upstream from reference (0.0) REF.

Luminance calculations place the observer’s (motorist’s) eye height at 4.8 ft. 1.45 m) above grade.The 4.8 ft. 1.45 m) is a design figure used internationally and does not affect the driver eye height of3.5 ft. (1 O7 m). The observer’s line of sight is downward at one degree below horizontal and parallel to

the edge of the roadway along lines one-quarter roadway lane width from the edge of each lane. Theobserver is positioned at a point 272 ft. (83.07 m) before the first point in the cycle to be evaluated.

Luminance Unqormity C alculation. Luminance uniformity is calculated both as the ratio of averagelevel to minimum point and maximum point to minimum point. The average-to-minimum-point methoduses the average luminance of the roadway design area between two adjacent luminaires divided by thelowest value at any point in the area. The maximum-to-minimum-point method uses the maximum andminimum values between the same adjacent luminaires. Luminance uniformities correlate closely withthe observer’s ability to detect differences in brightness levels.


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Ghre Evaluation. In conjunction with the luminance method, the evaluation of glare from the fixedlighting system is relevant and included with the luminance criteria. The disability glare (veiling luminance)has been quantified to give the designer the information to identify the veiling effect of glare as a percentof average overall luminance.

Visibili ty-Based Design Methods

An alternate design method named small target visibility (STV) was proposed by the IlluminatingEngineering Society of North America (IESNA) in RP-8-1990 and was not adopted. With some mod-ification, the STV method was adopted as RP-8-2000. The STV method has not been adopted by thisguide, because i t does not adequately describe visibility in the roadway scene for the followingreasons:

The research shows that minor changes in the roadway lighting system that may cause large changesin the target visibility level VL) values-because only the targets and their immediate backgroundare considered-may not have a significant effect on the information content of the overall scene.Isolation on the VL of a small target is clearly too restrictive.The potential error in the calculation of target visibility is unacceptably high for engineeringcalculations.Calculations do not include off-roadway sources or headlamps of multiple vehicles, as is typicallyfound in practice.The visibility of objects varies substantially with respect to observation distance. Static observationdistance does not describe the visibility of small targets in general on a roadway and certainly doesnot describe the overall visibility of the roadway environment.The visibility of small targets on an empty roadway does not describe driver information needs suf-ficiently to be used as a measure of safety.STV methods require too many simplifying assumptions that introduce unrecognized error into theresult. This makes it an approximation at best, and totally inaccurate at worst.The contribution of pavement reflectance to visibility-based design is not adequately recognized.

Background luminance is one of two fundamental design parameters. Before a reliable visibility-based design methodology can be developed, modern pavement reflectance data must be obtained,the change in pavement reflectance with respect to traffc must be well known, and the effect ofvariable pavement reflectance on contrast must be known. In addition, the effect of driver obser-vation angle change must also be fully understood before pavement reflectance can be accuratelyestimated.The validity of the design calculations are further questioned because many of the physical para-meters used are variable over time. The pavement?s reflective characteristics will change withage. The luminaires will accumulate dirt and bum out, thus changing their output characteristics.The amount of off-road lighting that contributes to visibility on the road changes as developmentalong the lighted area changes. Finally, normal weather variations such as rain and ice totally

invalidate the design calculations by changing the pavement?s reflective characteristics from dif-fuse to specular.

Recent research on information theory (and the calculation tools provided by similarity theory) (1) fur-nish a powerful and attractive tool for analyzing roadway lighting design. The combination of digitalimaging and IT-based processing algorithms was successfully used to quantify a predictable function ofvisibility. These are likely to be the future of visibility based designs in lieu of target visibility.

16right American Association of State Highway and Transportation Officialsded b IHS nder license ith AASHTO Licensee=Aramco HQ/9980755100 User=Villa Jose

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3.2 WARRANTING CONDITIONS

General

This discussion summarizes available conclusions for the selection of those sections of freeways onwhich fixed source lighting may be warranted. These warrants may be applied to roadways other thanfreeways, as practicable.

Benefits of Lighting

The investment of public funds in roadway lighting returns benefits to the public in several ways.Lighting benefits motorists by improving their ability to see roadway geometry and other vehicles atextended distances ahead. This results in greater driver confidence and improved safety, particularly ininclement weather. Lighting may also improve roadway capacity. Other benefits include improved pedes-trian safety, improved public safety and security, convenience, and civic pride and recognition.

It is generally recognized that traffic safety benefits resulting from fixed source lighting correspond insome proportion to traffic volume. High volume is inevitable on freeways in urban and suburban areas.The number of stalled vehicles and other emergency stops is proportional to traffic volume.

Rural Interchanges

An unlighted rural interchange often presents unique conditions that require special considerationbefore conclusions regarding lighting can be reached. Rural interchanges normally have ample space forsign installation. Where the interchange type and detail are typical of most others on the freeway, and adelineator system is included, the diverging and merging areas may be well understood and reasonablydiscernible without lighting. However, installation of a few lighting units at the point of on- or off-move-ments and ramp terminals could contribute to driver ease by providing visual indication for the maneuverareas. Many rural interchanges with low traffic volumes do not warrant roadway lighting. However, there

are circumstances under which partial interchange lighting is appropriate and still other conditions wherecomplete interchange lighting is the preferred treatment.

Warranting Condi tions

The warranting conditions in this section are for the purpose of establishing a basis on which lightingfor freeways may be justified. The warrants provide minimum conditions to be met whenever an agencyis contemplating lighting for new or existing facilities. Meeting of the warrants does not obligate the high-way agency to provide lighting. Jurisdictions may adopt higher numerical warranting values or morerestrictive subjective values for local use.

Master lighting plan ideas may be implemented in order to provide lighting at the times and places

most likely to provide the highest benefit to citizens.The decision to provide lighting, and the extent of that lighting once warranting conditions are met,

rests with the highway agency. In determining when and where lighting is to be provided, the agency mayadopt a policy that includes these warrants and is also based on such factors as availability of funds, traf-fic and crash data, roadway safety rating, etc. The warrants are not to be construed as the only criteria forjustifying lighting. The warrants are intended to be an easily understood tool to assist administrators anddesigners in considering lighting on roadways.

Local conditions, such as frequent fog, ice, snow, roadway geometry, ambient lighting, sight distance,signing, etc., could justify modification of these warrants.


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The following are separate warrants for continuous freeway lighting, complete interchange lighting,and partial interchange lighting.

Continuous Freeway Lighting

Description. A continuous lighting system provides relatively uniform lighting on all main lanes anddirect connections, and complete interchange lighting of all interchanges within the section. Frontageroads are not normally continuously lighted. The lighting units may be conventional luminaires or highmast assemblies or both.

Continuous lighting may be warranted under one of the conditions described in the following table.

TABLE 3 2. Warranting Condit ions for Continuous Freeway Lighting CFL)

Case

CFL- 1

CFL-2

CFL-3

CFL-4

Warranting Conditions

Sections in and near cities where the current average daily traffic (ADT) is 30,000 or greater.

Sections where three or more successive interchanges are located with an average spacing of1.5 miles or less, and adjacent areas outside the right-of-way are substantially urban incharacter.

Sections of two miles or more passing through a substantially developed suburban or urbanarea in which one or more of the following conditions exist:

a. local traffic operates on a complete street grid having some form of street lighting, partsof which are visible from the freeway

b. the freeway passes through a series of developments-such as residential, commercial,industrial and civic areas, colleges, parks, terminals, etc. that include lighted roads,streets, parking areas, yards, etc.-that are lighted

c. separate cross streets, both with and without connecting ramps, occur with an averagespacing of 0.5 miles or less, some of which are lighted as part of the local street system

d. the freeway cross section elements, such as median and borders, are substantially reducedin width below desirable sections used in relatively open country.

Sections where the ratio of night to day crash rate is at least 2.0 times the statewide average forall unlighted similar sections, and a study indicates that lighting may be expected to result in asignificant reduction in the night crash rate. Where crash data are not available, ratecomparison may be used as a general guideline for crash severity.

Definition Complete interchange lighting is defined as a lighting system that provides relative uniform lighting within the limits of the interchange, including:

main lanesdirect connectionsramp terminalsfrontage road or crossroad intersections.

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CIL-3

Complete interchange lighting may be warranted under one of the conditions described in the follow-ing table.

TABLE 3 3. Warranting Conditions for Complete Interchange Lighting CIL)

Where existing substantial commercial or industrial development that is lighted during hoursof darkness is located in the immediate vicinity of the interchange, or where the crossroadapproach legs are lighted for 0.5 mile or more on each side of the interchange.

(e h a r r a n in g Conditions

CIL- 1 Where the total current ADT ramp traffic entering and leaving the freeway within theinterchange areas exceeds 10,000 for urban conditions, 8,000 for suburban conditions, or5,000 for rural conditions.

Where the current ADT on the crossroad exceeds 10,000 for urban conditions, 8,000 forsuburban conditions, or 5,000 for rural conditions.

CIL-4 Where the ratio of night to day crash rate within the interchange area is at least 1.5 times the

statewide average for all unlighted similar sections, and a study indicates that lighting may beexpected to result in a significant reduction in the night crash rate.Where crash data are not available, rate comparison may be used as a general guideline forcrash severity.

Partial Interchange Lighting

Definition. Partial interchange lighting is defined as a lighting system that provides illumination onlyof decision making areas of roadways including:

acceleration and deceleration lanes

ramp terminalscrossroads at frontage road or ramp intersectionsother areas of nighttime hazard.

Partial interchange lighting may be warranted under one of the conditions described in the followingtable.

TABLE 3 4. Warranting Conditions for Partial Interchange Lighting PIL)

Case

PIL- 1

PIL-2

PIL-3

Warranting Conditions

Where the total current ADT ramp traffic entering and leaving the freeway within theinterchange area exceeds 5,000 for urban conditions, 3,000 for suburban conditions, or 1,000for rural conditions.

Where the current ADT on the freeway through traffic lanes exceeds 25,000 for urbanconditions, 20,000 for suburban conditions, or 10,000 for rural conditions.

Where the ratio of night to day crash rate within the interchange area is at least 1.25 times thestatewide average for all unlighted similar sections, and a study indicates that lighting may beexpected to result in a significant reduction in the night crash rate.Where crash data are not available, rate comparison may be used as a general guideline forcrash severity.


Not for Resale 03/01/2007 05:32:21 MSTprod ction or net orking permitted itho t license from IHS

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35/78


Special Considerations

Continuous, complete-interchange or partial-interchange lighting is considered justified where thelocal governmental agency finds sufficient benefit in the forms of convenience, safety, policing, commu-nity promotion, public relations, etc. to pay an appreciable percentage of the cost of or wholly finance theinstallations, maintenance, and operation of the lighting facilities. For detail