Introduction: 1 Intersection Safety Issue Briefslibraryarchives.metro.net/...intersection-safety-issue-briefs-april.pdf · The materials could also be used by a far wider audience

Enclosed is a series of Issue Briefs on various intersection safety-related topics. This is the SecondEdition of these briefs. The issue briefs are targeted primarily for traffic engineers and trans-portation and safety professionals. Many products have developed over the past two years thatwill help practitioners evaluate causes of intersection crashes and potential solutions. The issuebriefs provide practitioners with a substantial number of references and resources for subsequentreview and consideration. The materials could also be used by a far wider audience of people andorganizations who want to promote intersection safety issues within their area of influence.

The topics that are included within this intersection safety communications kit include:

1 Introduction2 The National Intersection Safety Problem3 Traffic Control Devices: Uses and Misuses4 Stop Signs5 Signals6 Engineering Countermeasures to Reduce Red Light Running7 Red-Light Cameras8 Intersection Safety Countermeasures9 Pedestrian Safety10 Older Drivers11 ADA Considerations at Intersections12 Human Factors13 Access Management14 Roundabouts15 Road Safety Audits16 Work Zones17 Resources

The issue briefs are available in print form or electronically on the Federal Highway AdministrationWeb site at www.fhwa.dot.gov and on the Institute of Transportation Engineer’s Web site atwww.ite.org. Issue briefs are available for organizations to use and post on their Web sites. Thegoal is to provide this information to the widest audience possible within the education, lawenforcement and engineering communities and to the general public.

The format of the issue briefs has changed with the second edition. They are now three-holepunched and can easily be placed in a notebook for quick access and for reproduction as required.

Introduction:Intersection Safety Issue Briefs

1INTRODUCTION April 2004

U.S. Department of TransportationFederal Highway Administration

11

Richard A. Cunard, P.E.Transportation Research Board

Gregory W. Davis Federal Highway Administration

Philip Demosthenes PMX Inc.

John FeganFederal Highway Administration

Margaret Gibbs, P.Eng., PTOEHamilton Associates

Geoffrey Ho, M.Eng., P.EngG. Ho Engineering Consultants

Robert P. Jurasin, P.E.Wilbur Smith Associates

William C. Kloos, P.E.City of Portland

Stein Lundebye, P.E.The World Bank

Hugh W. McGee, Sr., P.E.BMI-SG Inc.

John McGill, P. Eng., PTOESynectics Transportation Consultants Inc.

Barbara McMillenFederal Highway Administration

Richard B. Nassi, P.E.City of Tucson

Mike NiederhauserMaryland State Highway Administration

Stanley F. PolanisCity of Winston-Salem, North Carolina

Tamara RedmonFederal Highway Administration

Matthew Ridgway, AICPFehr & Peers Associates Inc.

Michael Robinson Federal Highway Administration

Ida van Schalkwyk University of Arizona

William J. Scully, P.E.MS Transportation Systems

Edward R. Stollof, AICPInstitute of Transportation Engineers

W. Scott Wainwright, P.E., PTOEFederal Highway Administration

Brian WalshWashington State Department of Transportation

Sany R. Zein, M.Eng., P.Eng.Hamilton Associates

Introduction: Intersection Safety Briefing Sheets

ITE and FHWA would like to thank the following reviewers and/or contributors. In addition, we wantto thank Mark Dunn, Iowa Department of Transportation/Center for Transportation Research andEducation (CTRE) for the use of materials within CTRE’s Traffic Safety Information Series, and LindaVoss, Kansas Department of Transportation (KDOT), for use of materials incorporated within anumber of KDOT’s safety publications.

INTRODUCTION April 2004 2

Should your office require print copiesof the Intersection Safety Issue Briefs,please contact:

Edward StollofInstitute of Transportation Engineers1099 14th Street, NWSuite 300 WestWashington, DC 20005Tel: 202-289-0222 x132Fax: 202-289-7722E-mail: [email protected] site: http://www.ite.org

or

Hari Kalla, P.E.Federal Highway Administration400 Seventh Street, SWSuite 300 WestWashington, DC 20005Tel: 202-366-5915Fax: 202-366-2249E-mail: [email protected] site: http://www.fhwa.dot.gov

Identifying the ProblemIn 2002 approximately 3.2 million intersection-related crashes occurred, representing 50 per-cent of all reported crashes. 9,612 fatalities (22percent of total fatalities ) occurred at or with-in an intersection environment (See Table 1).The cost to society for intersection crashes isapproximately $96 billion a year. The numberof fatal motor vehicle crashes at traffic signalsis rising faster than any other type of fatal crashnationwide.

An intersection is, at its core, a planned pointof conflict in the roadway system. With differ-ent crossing and entering movements by bothdrivers and pedestrians, an intersection is oneof the most complex traffic situations that motorists encounter. Add the element of speedingmotorists who disregard traffic controls and the dangers are compounded.

Despite improved intersection design and more sophisticated applications of traffic engineeringmeasures, the annual toll of human loss due to motor vehicle crashes has not substantially changedin more than 25 years.

Intersection safety is a national, state and local priority. Intersections represent a disproportion-ate share of the safety problem. As a result, organizations such as the Federal HighwayAdministration, the Institute of Transportation Engineers and AASHTO,AAA and other private andpublic organizations are devoting resources to help reduce the problem.

The National IntersectionSafety Problem

1INTERSECTION SAFETY PROBLEM April 2004


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Table 1:Key 2002 National Highway and Traffic

Administration (NHTSA) Statistics

Number Percentage Societal Cost in Billion $

Total fatality crashes 38,409Total intersection-related fatality crashes 8,760 22.8 22

Total injury crashes 1,929,000Total intersection-related injury crashes 1,066,000 55.3 69

Total property-damage-only (PDO) crashes 4,348,000Total PDO intersection-related crashes 2,092,000 48.1 5

All crashes 6,316,000 96Total intersection-related crashes 3,170,000 50.2

Total fatalities 42,815Fatalities at intersections 9,612 22.4

The National Intersection Safety Problem

Figure 1 shows the 2002 percentage offatal intersection crashes, by type oftraffic control present at the intersec-tion. As shown, there is a balanced dis-tribution of fatal crashes occurring at atraffic signal and a stop sign (approxi-mately one in three crashes each occurat a signal and stop sign.) It is note-worthy that almost one in three crash-es occur in locations that have no traf-fic controls present. A street “with notraffic control” is one where there is nocontrol signal or stop sign for traffic onthe street being crossed.

Figure 2 shows the distribution of the8,760 fatal intersection crashes by man-ner of collision. As shown, the sideimpact crashes are the most predomi-nate crash type. Side impact crashesaccount for over 60 percent of the fatalintersection collisions. Rear-end andhead-on crash types each account for fivepercent of fatal intersection crashes.Almost one in three fatal crashes at inter-sections do not involve a collision withanother motor vehicle that is in motion.

Designing andOperatingIntersections forAll UsersTransportation engineers must designand operate intersections for all usersincluding

� pedestrians� bicyclists� older drivers and younger drivers� pedestrians of all ages and cogni-

tive and physical abilities/disabilities� transit/light rail/trolley vehicles� trucks including loading/unloading

maneuvers� emergency vehicles� proximate driveways serving com-

mercial properties � commuters

There will be tradeoffs regarding capac-ity, priority, and operations of an inter-section—that is a given. These tradeoffscan only be made when good informa-tion is provided to policymakers regard-ing both dominant and special user pop-ulations within and proximate to anintersection.

Tackling theIntersectionSafety ProblemRequires aMulti-disciplinaryApproachIntersection safety is a complex publichealth issue that cannot always be solvedby making changes in signs and signals,but can be helped by a national compre-hensive effort of improved intersectionvehicle and pedestrian safety manage-ment.

The following actions address ways toachieve substantial reductions in annualcrashes, injuries and fatalities:

� Analyze the reasons for trafficconflicts at intersections. Multi-disciplinary teams (engineers,enforcement, human factors pro-fessionals, etc) are recommendedsince they can have a broader per-spective on crash causes.

� Engage in innovative andstrategic thinking. Engineers

must delicately balance the require-ment for efficient traffic movementand congestion reduction and, atthe same time, the need to protectvehicle occupants and pedestriansfrom the consequences of danger-ous vehicle maneuvers and unwisepedestrian behavior.

� Modify the intersection designand operations based on engi-neering analysis

� Identify the safety benefits ofreconstruction or construc-tion projects and/or opera-tional changes that areplanned at intersections. Selectalternatives that have the greatestsafety benefit. Integrate safety eval-uations of projects into the plan-ning and design processes.

� Provide sustained and consis-tent law enforcement efforts.

� All levels of government mustplay a central role by providingimproved funding, and cooperationwith highway and vehicle engineers,health care authorities, law enforce-ment, national safety organizations,and local citizen safety groups.

INTERSECTION SAFETY PROBLEM April 2004 2

Figure 1

Figure 2

OverviewTraffic control devices are signs, signals, pavement markings and other devices placed along high-ways and streets to move vehicles and pedestrians safely and efficiently.Theses devices are placedin key locations to guide traffic movement, control vehicle speeds and warn of potentially haz-ardous conditions.They also provide important information to drivers about detours and trafficdelays.

Functions of Traffic Control DevicesThe main purpose of a traffic control device is to provide information to drivers so they can oper-ate their vehicles safely along a highway or street.The five basic criteria of a traffic control deviceare to:

� Fulfill a need;� Command attention;� Convey a clear, simple meaning;� Command respect from road users, and� Give adequate time for response.

Signs, signals, pavement markings, cones, barricades and warning lights are designed with dedicat-ed colors, shapes and sizes based on the different functions they provide.They regulate, guide andwarn vehicle and pedestrian traffic about road conditions. Uniformity of design (color, shape, sizeand location) helps drivers to quickly understand the messages of traffic control devices.Consistency is important for driver respect, recognition and proper reaction to the devices.

Characteristics of Uniform TrafficControl DevicesColor. Certain colors are used to trigger instant recognition and reaction; for example, STOPsigns are always red. Similarly, signals at intersections must have the same sequence of red/yel-low/green to communication stop/warning/go to drivers and pedestrians.

Nighttime visibility. Traffic control devices are made visible under nighttime operating condi-tions by either being separately lighted or retro-reflectorized so that the light coming from vehi-cle headlamps is bounced off signs and other devices back to the eyes of drivers.

Daytime visibility. Traffic control devices are designed with highly visible colors or a sharp con-trast of messages against a background. Sometimes traffic control devices are lighted even for day-time viewing to draw the attention of drivers to their messages.

Shape and size. Signs have standard shapes and sizes to trigger instant recognition and reaction.For example, STOP signs have an octagonal shape of a particular size that no other sign is per-mitted to have.There are similar specifications for the shapes and sizes of many other traffic con-trol devices for both permanent and temporary conditions.

Location.Traffic control devices must be placed in locations that provide enough time for all driv-ers to make the appropriate safe maneuvers, such as entering or departing a road or stopping andturning to avoid conflicts with other vehicles and pedestrians.

Traffic Control Devices:Uses and Misuses

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Traffic Control Devices: Uses and Misuses

Messages. Traffic control devices aredesigned with carefully chosen symbolor word messages of specific sizes andcontent. Locations and functions arethen selected in relation to the amountof time that drivers need to detect, readand understand messages to makeappropriate vehicle maneuvers.

How to Selectthe CorrectTraffic ControlDeviceTraffic control devices work in concertwith the basic “rules of the road” con-tained in traffic laws and ordinances,including each states’ uniform code thatregulates vehicle movements. Oneexample is the “right-of-way” principlethat determines which driver has prior-ity when approaching or entering anintersection.

Traffic control devices have undergonea long evolution of design and installa-tion criteria. Current designs and thestandards for using them are the resultof several decades of scientific investiga-tion and the combined experience ofmany professional engineers, humanbehavior and vision researchers andsafety policy-makers.

One of the major resources for deter-mining the design and use of traffic con-trol devices is the Manual on UniformTraffic Control Devices (MUTCD). The2003 Edition of the MUTCD is thenational standard applicable to all publicroads.The MUTCD provides standards,guidance and application informationfor signs, markings, traffic signals andother traffic control devices.This docu-ment can be found on the Web site:http://mutcd.fhwa.dot.gov/.

Additional basic design guides havebeen produced by the Institute ofTransportation Engineers’ such as theTraffic Engineering Handbook and TrafficControl Devices Handbook. These docu-ments can be ordered through the ITEBookstore at http://www.ite.org.

CommonProblems withTraffic ControlDevicePlacement andInstallation

Due to resource constraints, manyjurisdictions do not have traffic engi-neers or traffic engineering technicianson staff.These jurisdictions may rely onpersonnel that may have an engineeringbackground; however, they may not bespecifically trained in traffic engineering.Knowledge of the standards, guidanceand applications included in theMUTCD is an essential element in thedesign, construction, operation andmaintenance of roadway segments andintersections. A few of the commonproblems with traffic control deviceplacement and installation are providedbelow.

1. Use of an improper device.Placing an unwarranted traffic sig-nal where a less restrictive controlwould be more appropriate mayresult in unnecessary delays,excessive violations, increasedcrashes and diversion to less desir-able routes such as residentialstreets.

2. Improper placement. A trafficcontrol device at the wrong loca-tion may result in the device beingseen too late by drivers to safelyreact (e.g., placing a properlydesigned sign too far around thebend of a sharp curve).

3. Wrong color, shape, or size.Using a color, shape, or size for asign or other traffic control devicethat is in conflict with the MUTCDcan result in the inability of drivers

to detect and comprehend theneed to make safe maneuvers andcan cause inattention or visibilityproblems (i.e., “I didn’t see theSTOP sign.”)

4. Land use, traffic and otherchanges can cause existingtraffic control devices tobecome obsolete. As an exam-ple, traffic signs that may have con-trolled the movement of vehiclesand pedestrians for years may nolonger be effective in doing so.

5. Lack of signs or other devicesto warn drivers and pedestri-ans of unexpected, potentiallyhazardous conditions. Forexample, neglecting to provideadvance warning of an upcomingsignal or STOP sign over the top ofa steep hill can result in inappro-priate braking and steering maneu-vers that may result in collisions.

6. Poor Maintenance. Signs andpavement markings need to bemaintained on a regular basis.Faded signs and pavement mark-ings make them harder for roadusers to detect and may lead topotentially dangerous situations.For example, faded STOP signsmay lead to drivers entering anintersection without stopping.

TRAFFIC CONTROL DEVICES April 2004 2

Purpose of a STOP SignThe STOP sign is a regulatory sign that is used when trafficis required to stop. It is a red octagon that has a white bor-der and large white letters that read STOP. At multi-waystop intersections, a small plate is placed below the stop signto inform the driver of how many approaches are requiredto stop.

The Manual of Uniform Traffic Control Devices (MUTCD)describes STOP signs (R1-1), including applications andplacement. STOP signs are used to assign right-of-way at anintersection. Since a STOP sign causes inconvenience tomotorists, it should be used only where warranted.

Where Should A STOPSign Be Installed?STOP signs should be located where vehicles are to stop or as near to that point as possible.Thesign may also be supplemented with a STOP line and/or the word STOP on the pavement.

Where there is a marked crosswalk, the STOP sign should be located approximately 4 ft. inadvance of the crosswalk line.When only one STOP sign is used on an intersection approach, itshould be on the right side of the roadway.

At wide intersections however, placing an additional sign on the left side of the approach mayreduce violations of the STOP sign and the likelihood of right-angle crashes.

If two lanes of traffic exist on an approach, at least one STOP sign should be visible to each laneof traffic.

Under What Conditions Should a Two-WaySTOP Sign Be Installed? Intersections must have one or more of the following conditions for two-way STOP signs to beinstalled:

� An intersection of a minor and major road, where the application of the normal right-of-way-rule would be hazardous;

� A street enters a highway;� An unsignalized intersection in a signalized area; and� Locations where there is a combination of high speed traffic, restricted view, and a previous

crash record that indicates a need for STOP sign control.

The advantage of a two-way stop is that the major flows do not have to stop and they incur almostno delay at the intersection (i.e., the majority of the traffic does not have to stop).

STOP Signs

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STOP Signs

Under WhatConditionsShould a Four-Way (Multi-way)STOP Sign BeInstalled?Four-way STOP signs are often used atthe intersection of two roadways thatexhibit approximately equal traffic vol-umes. The following criteria should beconsidered:

� A traffic signal is going to beinstalled and the intersectionneeds a temporary solution tocontrol the traffic;

� Within 12 months, at least fivecrashes have occurred at theintersection that could have beenprevented by STOP signs. Previouscrash records include right- andleft-turn collisions, as well as right-angle collisions;

� Minimum traffic and pedestriansvolumes;

� 85th percentile major-street vehi-cle speeds in excess of 40 mph;

� Average minor street vehicledelays of at least 30 sec. during themaximum hour;

� The need to control left-turn con-flicts;

� The need to control vehicle/pedestrian conflicts near locationsthat generate high pedestrian vol-umes;

� Locations where a road user, afterstopping, cannot see conflictingtraffic and is not able to safelynegotiate the intersection unlessconflicting cross traffic is alsorequired to stop; and

� An intersection of two residentialneighborhood collector (through)streets of similar design and oper-ating characteristics where multi-way stop control would improvetraffic operational characteristicsof the intersection.

Failure to Stopat Existing STOPSignsWhen there is a history of drivers fail-ing to heed STOP signs that clearly haveadequate visibility, the followingapproaches could be considered:

� Install STOP AHEAD sign;

� Increase size of STOP and STOPAHEAD signs from 30 to 36 in.;

� Install two transverse rumblestrips in the approach lane inadvance of the STOP AHEAD andbefore the STOP sign;

� Consider installation of two addi-tional transverse rumble strips tosupplement the first two locations;

� Install intersection illumination;

� Consider adding a flashing red bea-con in conjunction with the STOPsigns or an overhead intersectioncontrol beacon with flashing redfor the minor street and flashingyellow for the major street;

� Place actuated flashers on the topof a STOP sign. A detector wouldbe in the pavement in advance ofSTOP sign. As a vehicle approach-es, a red flasher would appear.Thissolution would address the driverexpectancy problem and givemore attention to the STOP sign;and

� Use of double-indicating left-sideSTOP sign.

ResourcesThe MUTCD is located at the followingWeb site: mutcd.fhwa.dot.gov.

Ellison, James W., P.E. Case Study: Failureto Stop at a Stop Sign: A ProgressiveApproach.http://www.ite.org/library/Intersection

Safety/ Ellison.pdf.

SIGNS April 2004 2

Purpose of Traffic SignalsTraffic signals are used to assign vehicular and pedes-trian right-of-way. They are used to promote theorderly movement of vehicular and pedestrian trafficand to prevent excessive delay to waiting traffic.

Traffic signals should not be installed unless one of thewarrants specified by the Manual on Uniform TrafficControl Devices (MUTCD) has been satisfied.The satis-faction of a warrant is not in itself justification for a sig-nal. A traffic engineering study must be conducted todetermine if the traffic signal should be installed.

The installation of a traffic signal requires sound engineering judgment and must balance the fol-lowing, sometimes conflicting, goals:

� Moving traffic in an orderly fashion;� Minimizing delay to vehicles and pedestrians;� Reducing crash-producing conflicts; and� Maximizing capacity for each intersection approach.

Where Should A SignalBe Installed?The MUTCD lists eight warrants for the placementof traffic signals. Readers are encouraged to reviewPart 4 of the MUTCD for greater specificity regard-ing signal warrants. Access management considera-tions and the spacing of signals on arterial roadwaysare critical elements of system efficiency and oper-ational safety.

The basic question that must be answered is “Will this intersection operate better with or with-out a traffic signal?”

Advantages of SignalsWarranted traffic signals properly located and operated, usually have one or more of the follow-ing advantages:

� Provide for orderly movement of traffic;� Increase traffic capacity of the intersection;� Reduce the frequency of certain types of crashes, (e.g. right-angle crashes);� Provide for continuous or nearly continuous movement of traffic along a given route; and� Interrupt heavy traffic to permit other traffic, vehicular or pedestrian, to cross.

Traffic Signals

1TRAFFIC SIGNALS April 2004


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Factors toConsider WhenInstalling a SignalA number of factors should be consid-ered when planning to signalize anintersection.These factors include:

� The need to balance delay.Excessive delay results in signifi-cant fuel waste and highermotorist costs and air pollution.Solution: signal timing improve-ments.

� Potential diversion of arterial traf-fic neighborhood streets. Solution:signal timing improvements.

� Red-light running violations andassociated crashes. Solution: SignalTiming,Adequate Yellow ClearanceInterval/All-Red Interval.

� Cost. The cost for a signal rangesfrom $50,000 to more than$200,000 based on the complexityof the intersection and the charac-teristics of the traffic using it. Inaddition, the annual operating costof each signal ranges from $1,000to $5,000.

Signal Improvements ThatMay Decrease Crashes

� Signal retiming;� Signal phasing and cycle improve-

ments;� Review and assure adequacy of

yellow change interval/all-redclearance interval for safer travelthrough the intersection;

� Use of longer visors, louvers, back-plates and reflective borders;

� Installation of 12 in. signal lenses;� Install additional signal heads for

increased visibility;� Provide advance detection on the

approaches so that vehicles arenot in the dilemma zone when thesignal turns yellow;

� Repositioning of signals overhead(via mast arm) instead of postmounted;

� Use of double red signal displays;and

� Remove signals from late nightearly morning programmed flash.

Table 1, Signalization Countermeasuresat Signalized Intersections, includes spe-cific categories of countermeasuressuch as signal operational improve-ments, signal hardware and combination

signal and other improvements. Thetable provides the effectiveness interms of the percentage potential crashreductions that might be experienced, ifavailable. This table is also found inBriefing Sheet No.8, which includes amore comprehensive toolbox of coun-termeasures for consideration at inter-sections. Traffic engineers and othertransportation professionals can usethe information in this Briefing Sheetwhen the public or an elected orappointed official asks a question suchas:

What is the range of solutionsthat might be considered at thesignalized intersection of “Maple”and “Elm” streets due to the highnumber of total crashes and left-turn crashes?” What low-costimprovements can be tried first?If these improvements don’t giveus a higher degree of safety, whatelse can we try?

Traffic engineers will need to considersite-specific environmental, geometricand operational conditions before mak-ing a judgment regarding those counter-measures that can be applied to a par-ticular intersection.

Traffic Signals

TRAFFIC SIGNALS April 2004 2

Traffic Signals


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55Table 1:

Signalization Countermeasures at Signalized IntersectionsNumbers in [n] indicate references used for Table 1

Numbers prior to the [n] represent the range of % crash reduction that might be expected from implementing a given improvement.

� Countermeasure/Crash Type identified; however no estimate of effectiveness is provided.

Potential Effectiveness(Percentage Reduction)

Improvement Type(s) Cost Total Right Angle Left Turn Rear-end Sideswipe Pedestrian Red-Light OlderCrashes Crashes Crashes Crashes Running Driver

SIGNAL OPERATIONS IMPROVEMENTS

Interconnect/Coordinate Medium 15-17 [1] 25-38 [12] � � [2]Traffic Signals; Optimization

Increase/Modify Clearance Intervals Low 4-31 [1,9,10] 1-30 [1,9] � � [2]Improve Signal Timing (General) Low 10-15 [1] � � � �

Add Protected/Permissive LT Phase Medium 4-10 [1,9] 40-64 [1,9]Use Green Arrow/ Protected Left Low 3 [9] 98 [9] �

Turns/Movement Signal PhasingUse Split Phases Low 25 [11] � � �

Use Leading Pedestrian Interval Low 5 [8]Add Pedestrian Phase Medium 23-25 [1] 7-60 [1,8]Add Left-Turn Phasing to an Medium 23-48 [6, 12] 63-70 [1] 5 [8]

Existing Signal Provide Green Extension Variable � �

(Advance Detection)Install Signal Actuation Variable � �

Assume Slower Walking Speeds for Low � �

Pedestrian Signal TimingProvide Advance Warning of Signal Medium � � � �

Changes at Rural Signalized Intersections

Remove Signals from Late Night/Early Low 29[9] 80 [9]Morning Flash

Consider Restricting Right-Turns- Low �

on-RedConsider Installation of Pedestrian Low �

Countdown Signals(incremental cost)

Consider Installation of Animated Low �

Eye Signals (Incremental cost)

SIGNAL HARDWARE

Install Larger (12-Inch) Signal Lenses Low 10-12 [1,9] 48 [9] � � � �

Install Flashing Beacon at Intersection Medium 30-38 [1]Install Flashing Beacon at Advance Medium 25-28 [1] � [2]

of IntersectionReplace Pedestal Mounted Signal High 28-43 [12] �

with Mast ArmInstall Backplates on Existing Signals Low 2-24 [1,9] 7-93 [1,5,9] � � � [2] �

Optically Programmed Signal Lenses 15-18 [1] �

Provide Louvers,Visors, Special Lenses Low � � �

so Drivers are able to View Signals only for their Approach

Upgrade Signal Controller Medium 20-22 [1 8, 11] � � �

Relocate/Shield Signal Hardware in Medium [6] � � �

Clear Zone. Signal Hardware Should Not Obstruct Sight Lines.

Install Additional Signal Heads Medium 10 [9] 42 [9] � � � �

Install More Overhead Traffic Signals High � � � � �

Provide Two Red-Signal Displays Medium �[2]within each Signal Head to IncreaseConspicuity of the Red Display

Use LED Traffic Signal Module. Medium � [2]Stripe for Left-Turn Lane within Low 26 [9] 66 [9]

Existing RoadwayRed T-Display Medium 9 [9] 36 [9]

Traffic Signals

References forTable 11. Agent, Kenneth R. et. Al. Development of

Accident Reduction Factors. Research ReportKTC-96-13. Kentucky Transportation CenterCollege of Engineering, June 1996.

2. Institute of Transportation Engineers.Engineering Countermeasures to Reduce Red-Light Running.Washington, DC: ITE, 2003.http://safety.fhwa.dot.gov/rlr/rlrreport/RLRbook.pdf

3. FHWA Older Driver Handbook.

4. Harwood, D.W., F. M. Council, E. Hauer,W. E.Hughes, and A.Vogt. Prediction of the ExpectedSafety Performance of Rural Two-Lane Highways,Report No. FHWA-RD-99-207. Washington,DC: Federal Highway Administration, 2000.

5. Institute of Transportation Engineers. TrafficSafety Toolbox: A Primer on Traffic Safety.Washington, DC: ITE, 1999.

6. NCHRP 17-18 (3). Initial Draft Compendiumof Strategies, Signalized Intersections, Phase II.Draft April 29, 2002.

7. NCHRP, 500. Volume 5: A Guide for AddressingUnsignalized Intersection Collisions.http://gulliver.trb.org/publications/nchrp/nchrp_rpt_500v5.pdf

8. MetroPlan Orlando. Orlando Urban AreaArterial Pedestrian Crash Study. Orlando:MetroPlan Orlando, July 12, 2000.

9. Polanis, Stanley F. Low Cost SafetyImprovements. City of Winston-Salem, NorthCarolina, November 2003.

10. Retting. R. M. Greene. Influence of Traffic SignalTiming on Red-Light Running and PotentialVehicle Conflicts at Urban Intersections,Transportation Research Record 1595.Washington, DC:TRB, 1997.

11. SEMCOG. Traffic Safety Manual, SecondEdition. September 1997.http://www.semcog.org/TranPlan/TrafficSafety/assets/Safety_Manual.pdf

12. Thomas, Gary B. and Daniel J. Smith.Effectiveness of Roadway Safety Improvements,Final Report. Highway Division of the IowaDepartment of Transportation, CTREManagement Project 00-61, March 2001.

13. TEXDOT 1995.

Other References ConsultedCTRE, Traffic and Information Series FactSheet 15: “What is the Harm in Installing anUnwarranted Traffic Control Device?”

Kansas Department of Transportation,Bureau of Traffic Engineering, Are Traffic SignalsReally A Cure-All.

Manual on Uniform Traffic Control Devices.http://mutcd.fhwa.dot.gov/

Pedestrian-Bicycle Information Center Website. http://www.walkinginfo.org

US Department of Transportation, PTI,FHWA-OP-03-069. Unclogging Arterials,Prescription for Relieving Congestion andImproving Safety on Major Local Roadways.

South Dakota Department of Transportation.Development of South Dakota Accident ReductionFactors: SD 98-13,August 1998.http://www.state.sd.us/Applications/HR19ResearchProjects/Projects/SD1998_13_final_report.pdf




COMBINATION SIGNAL AND OTHER IMPROVEMENTS

Construct Left-Turn Lanes with High � � �

Signal UpgradesLeft-Turn Lane, Signal and NO High 21-25 [1] 46-54 [1] �

Turn PhaseLeft-Turn Lane, Signal PLUS High 25-36 [1] 43-45 [1] �

Turn Phase Add Left-Turn Phasing AND Turn High 46-69 [12] � � �

Lanes to an Existing Signal Removal Signal, Develop a Program Low 50-53 [1] � �

to Identify and Remove Unwarranted Signals.

Install 12” Signal Heads and SIGNAL Low 11 [9] 36 [9]

Table 1 (continued) Signalization Countermeasures at Signalized Intersections

National StatisticsCrash data from the National Highway Traffic SafetyAdministration indicates that in 2002, there were 921fatalities and 178,000 injuries resulting from 207,000crashes attributable to motorists running red lights at sig-nalized intersections. Crashes involving red-light runningare much more likely to cause an injury or a fatality thanother intersection crashes. The number of fatal motorvehicle crashes at traffic signals is rising faster than anyother type of fatal crash nationwide:

� Red-light running (RLR) has become a national safe-ty problem with a societal cost estimated at $14 bil-lion per year;

� Motorists are more likely to be injured in crashesinvolving RLR than in other types of crashes.Occupant injuries occurred in 45 percent of the RLR crashes, compared to 30 percent forother crash types; and

� According to a survey conducted by the U.S. Department of Transportation and theAmerican Trauma Society, 63 percent of Americans witness a RLR incident more than oncea week. One in three Americans knows someone who has been injured or killed because ofa red-light runner

When does RLR occur?RLR occurs when a driver enters an intersection after the traffic sig-nal has turned red.The reasons that motorists run red lights are var-ied and are both intentional—“in a hurry and didn’t want to wait”—and unintentional—“my vision to the signal was blocked.” Accordingto survey research, drivers believe RLR is often an intentional actwith few legal consequences. The traditional way of enforcing thisviolation is to station a patrol vehicle near an intersection. Thismethod is dangerous for the officer, expensive to localities anddrains valuable police resources.

Engineering Countermeasures to Reduce RLR

ITE and the Federal Highway Administration developed a publicationentitled Making Intersections Safer: A Toolbox of EngineeringCountermeasures to Reduce Red-Light Running: An Informational Report.

The principal objective of the publication is to identify the engineering design and whether oper-ational features of an intersection should be upgraded as necessary to discourage RLR.The engi-neering countermeasures can be grouped into four distinct areas:

� Improving signal visibility/conspicuity;� Increasing the likelihood of stopping;� Addressing intentional violations; and� Eliminating the need to stop.

EngineeringCountermeasures to ReduceRed-Light Running (RLR)

1RED-LIGHT RUNNING April 2004


66

Engineering Countermeasures to Reduce Red-Light Running

Table 1 summarizes the countermea-sures that can be considered under eachof the countermeasure groupings identi-fied above. A brief description of eachcountermeasure follows. In addition,Figure 1,Sample Assessment Sheet, on page4, shows the types of information that anengineer or an engineering technicianshould evaluate in the field. A separateassessment sheet would be completedfor intersection approach.

Descriptions ofSummary ItemsIncrease SignalVisibility/Conspicuity

Placement and Number of SignalHeads. Overhead-signal displays help toovercome the three most significantobstacles posed by pole-mounted signalheads,which are:(1) they generally do notprovide good conspicuity, (2) mountinglocations may not provide a display withclear meaning and (3) motorists’ line-of-sight blockage to the signal head due toother vehicles, particularly trucks, in thetraffic stream. Studies have shown signifi-cant reduction in accidents attributed toreplacement of pole-mounted signalheads with overhead-signal heads.

Signal for Each Approach Lane.Section 4D.15 of the Manual on UniformTraffic Control Devices (MUTCD) onlyrequires that “a minimum of two signalfaces shall be provided for the majormovement on the approach.” Under thisstandard, it would be acceptable to haveonly two signals on an approach withthree or more through lanes.When a sig-nal is positioned such that it is over the

middle of the lane, it is in the center ofthe motorist’s cone of vision, therebyincreasing its visibility.The additional sig-nal head further increases the likelihoodthat a motorist will see the signal displayfor the approach.

Size of Signal Displays. 12-in. signallenses should be considered for all sig-nals, and especially those displaying redindications, to increase signal visibility.

Programmable Lens Signals. Theoptically programmed or visibility-limitedsignals limit the field of view of a signal.They allow greater definition and accura-cy of the field of view. The MUTCDspeaks of visibility-limited signals mostlywith regard to left-turning traffic at anintersection. The MUTCD permits theuse of visibility limited signal faces in situ-ations where the road user could be mis-directed, particularly at skewed or close-ly-spaced intersections when the roaduser sees the signal indications intendedfor other approaches before seeing thesignal indications for their own approach.

Louvers.Louvers are used to avoid con-fusion on intersection approaches whereapproaching motorists may be able to seethe signal indication for anotherapproach, typically due to a skewedapproach angle at the intersection. Thepurpose of a louver is to block the viewof the signal from another approach.

LED Signal Lenses.LED units are usedfor three main reasons: they are veryenergy efficient, are brighter than incan-descent bulbs and have a longer lif eincreasing the replacement interval. LEDsignals may be noticeably brighter and

more conspicuous than an adjacent signalwith the incandescent bulb. LED trafficsignal modules have service lives of 6 to10 years as compared to incandescentbulbs that have a life expectancy of only12 to 15 months. However, researchregarding the impacts of LED signal lens-es on crash rates has not been undertak-en. There is a belief that LEDs arebrighter and last longer, and thereforewould provide safety benefits but this hasnot been quantified. Some studies havefound that LED’s tend to loose brightnessover time instead of exhibiting an imme-diate failure.

Backplates. Backplates are used toimprove the signal visibility by providing ablack background around the signals,thereby enhancing the contrast.They areparticularly useful for signals oriented inan east-west direction to counteract theglare effect of the rising and setting sunor areas of visually complex backgrounds.A retroreflective yellow border striparound the outside perimeter of signalbackplates has been found to significantlyreduce night-time crashes at signals andalso helps drivers identify an intersectionas signalized during a power failure.

Increase Likelihood ofStopping

Signal Ahead Signs. The MUTCDrequires an advance traffic control warn-ing sign when “the primary traffic-controldevice is not visible from a sufficient dis-tance to permit the road user to respondto the device.”

Advance Warning Flashers. The pur-pose of an advance-warning flasher(AWF) is to forewarn the driver when a

RED-LIGHT RUNNING April 2004 2

Table 1:Summary of Engineering Countermeasures to

Reduce Red-Light Running

Increase Signal Visibility/Conspicuity Increase Likelihood of Address Intentional Violations Eliminate Need to StopStopping

Placement/Number of Signal Heads Signal Ahead Signs Signal Optimization Unwarranted Signals

Size of Signal Display Advance Warning Flashers Signal-Cycle Length Roundabout Intersection Design

Line of Sight: Programmable Lens Signals Rumble Strips Yellow-Change Interval

Line of Sight:Visors/Louvers Left-Turn Signal Sign All-Red Clearance Interval

LED Signal Lenses Pavement Surface Condition Dilemma Zone Protection

Backplates



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66traffic signal on his/her approach isabout to change to the yellow and thenthe red phase.

Rumble Strips. Rumble strips are aseries of intermittent, narrow, trans-verse areas of rough-textured, slightlyraised, or depressed road surface.Therumble strips provide an audible and avibro-tactile warning to the driver.When coupled with the SIGNALAHEAD warning sign and also thepavement marking word message—SIGNAL AHEAD—the rumble stripscan be effective in alerting drivers of asignal with limited sight distance.

Left-Turn Signal Sign. The LEFTTURN SIGNAL sign provides addition-al information not given in the actualsignal indication to the driver by speci-fying the control device for differentintersection movements.The MUTCDrequires this sign to accompany a sep-arate signal face controlling a “protect-ed-only mode” left turn movement(turn only allowed on green arrow)when that signal face uses a red ballindication. If the signal face uses a redleft-arrow indication, this sign is not tobe used.

Pavement Surface Condition. As avehicle approaches a signalized inter-section and slows to stop for a redlight, it may be unable to stop due topoor pavement friction and as a result,proceed into the intersection.Countermeasures to improve skidresistance include asphalt mixture(type and gradation of aggregate as wellas asphalt content), pavement overlaysand pavement grooving. Additionally,countermeasures such as the use of aSLIPPERY WHEN WET sign with a sup-plemental Advisory Speed Plate for alower advisory speed can be consid-ered.

Address IntentionalViolations

Signal Optimization. Interconnectedsignal systems provide coordinationbetween adjacent signals and areproven to reduce stops, reduce delays,decrease accidents, increase averagetravel speeds and decrease emissions. Ifdrivers are given the best signal coordi-

nation practical, they may not be ascompelled to beat or run a red signal.

Signal Cycle Length. Proper timingof signal-cycle lengths can reduce driv-er frustration that might result fromunjustified short or long cycle lengths.Longer cycle lengths means fewercycles per hour and therefore feweryellow-change intervals per hour andthus can reduce the number of oppor-tunities for traffic-signal violations. Onthe other hand, signal cycles that areexcessively long can encourage RLRbecause drivers do not want to have towait several minutes for the next greeninterval.

Yellow Change Interval. A properlytimed yellow interval is essential toreduce signal violations.An improperlytimed yellow interval may cause vehi-cles to violate the signal. If the yellowinterval is not long enough for the con-ditions at the intersection, the motoristmay violate the signal. Motorists havesome expectancy of what the yellowinterval should be and base their deci-sions to proceed or stop based ontheir past experiences. In order toreduce signal violations, the engineershould ensure that the yellow intervalis adequate for the conditions at theintersection and the expectations ofthe motorists.

All-Red Clearance Interval. An all-red interval is that portion of a trafficsignal cycle where all approaches havea red-signal display. If used, the all-redinterval follows the yellow-changeinterval and precedes the next conflict-ing green interval.The purpose of theall-red interval is to allow time for vehi-cles that entered the intersection dur-ing the yellow-change interval to clearthe intersection before the traffic-sig-nal display for the conflicting approach-es turns to green.

Dilemma Zone Protection. The“dilemma zone” has been definedrecently to be the area in which it maybe difficult for a driver to decidewhether to stop or proceed throughan intersection at the onset of the yel-low-signal indication. It is also referredto as the “option zone” or the “zone of

indecision” One potential counter-measure to reduce red-light running isto reduce the likelihood that a vehiclewill be in the dilemma zone at theonset of the yellow interval.This can beaccomplished by placing vehicle detec-tors at the dilemma zone.They detectif a car is at the dilemma zone immedi-ately before the onset of the yellowinterval. If a vehicle is there, the greeninterval can be extended so that thevehicle can travel through the dilemmazone and prevent the onset of the yel-low while in the dilemma zone.

Eliminate Need to Stop

Unwarranted Signals. If there is ahigh incidence of RLR violations, thismay be because the traffic signal is per-ceived as not being necessary and doesnot command the respect of themotoring public. Sometimes signals areinstalled for reasons that dissipate overtime. For instance, traffic volume maydecrease due to changing land-use pat-terns or the creation of alternativeroutes. The removal of a traffic signalshould be based on an engineeringstudy. Factors to be considered areincluded in ITE’s Traffic Control DevicesHandbook. If a signal is eliminated, thetraffic engineer must continue to mon-itor the intersection for potentialincreases in crashes.

Roundabout Intersection Design.When a roundabout replaces a signal-ized intersection, the RLR problem isobviously eliminated. Readers shouldconsult the Roundabout Safety BriefingSheet for further information.

References1. Institute of Transportation Engineers,

Publication IR-115, 2003. MakingIntersections Safer: A Toolbox of EngineeringCountermeasures to Reduce Red-LightRunning: An Informational Reporthttp://safety.fhwa.dot.gov/rlr/rlrreport/RLRbook.pdf

2. J. Bonneson, M. Brewer, and K.Zimmerman, Engineering Countermeasuresto Reduce Red-Light Running, FHWA –TX-03/4027-2 and, 04/4196-1 (Washington, DC:Federal Highway Administration, 2002)http://tcd.tamu.edu/Documents/4196-1.pdfhttp://tcd.tamu.edu/Documents/4027-2.pdf

Sample Assessment Sheet:Engineering Countermeasures to Reduce Red-Light Running

Intersection: ________________________________ with ____________________________________________________Approach Name: ____________________________ Direction Heading: Lanes at Intersection: ______________________

CHECK SIGNAL CONTROL PARAMETERS

Calculate the needed change period (CP) for this approach using agency practice or the following equation:

Calculated yellow: ________________ Calculated all-red: ________________ Are yellow and all-red adequate? Y N

CHECK SIGNAL VISIBILITY

Type of signal mounting: ________ Mast Arm ______ Span Wire________ Pole ________Can signal faces on other approaches be seen? Y NIs anything blocking the view of the signals (e.g. utility lines or foliage)? __________________________________________

CHECK SIGNAL CONSPICUITY

Is there visual clutter at the intersection that could detract from the signal? Y N At night? Y NAre the signal indications confusing? ______________________________ Could glare affect signal? __________________Is the left turn signal discernible from the through signal? ____________________________________________________

OPTIONS FOR CONSIDERATION

� Conduct signal warranting study � Relocate signal � Illuminate intersection

� Change yellow or red interval � Change signal mounting � Install backplates

� Provide dilemma-zone protection � Install additional signals � Install LEDs

� Modify cycle length � Install near-side signal � Install rumble strips on approach

� Coordinate signal � Install Advance Warning Flashers � Use visors or louvers

� Remove/relocate sight obstruction � Install larger signal lenses � Install LEFT TURN SIGNAL sign

� Install double red signal � Use programmable lenses � Install SIGNAL AHEAD sign



Measurement Reference Is Existing Adequate?

Distance upstream signal is feet MUTCD Table 4-1 Y Nvisible on approachDistance from stop bar to signal feetDiameter of signal lenses 8 inch 12 inch MUTCD Figure 4D-2 Y NNear side signal Y NNumber of signals Per MUTCD, at least 2 signals Y N

for the major movement

CP = 1.0 + +1.47 * V W + 20(10 + 64.4g) 1.47 * V

Yellow Interval Y = ____________seconds Approach speed V= ____________mphAll-red Interval AR= ____________seconds Cross street width W= ____________feetGrade (as decimal) g = ____________(uphill is positive) Cycle length C= ____________seconds

Red-Light RunningProblemCrash data from the National Highway TrafficSafety Administration indicates that in the year2002, there were 921 fatalities and 178,000injuries resulting from 207,000 crashes attribut-able to motorists running red lights at signalizedintersections.The number of fatal motor vehiclecrashes at traffic signals is rising faster than anyother type of fatal crash nationwide.

When does RLR occur?RLR occurs when a driver enters an intersection after the traffic signal has turned red.The rea-sons that motorists run red lights are varied and are both intentional (“in a hurry and didn’t wantto wait”) and unintentional (“my vision to the signal was blocked”).According to survey research,drivers believe RLR is often an intentional act with few legal consequences.The traditional way ofenforcing this violation is to station a patrol vehicle near an intersection.This method is danger-ous for the officer, expensive to localities and drains valuable police resources.

Using Red-Light Camerasto Reduce Red-LightRunning (RLR)

1CAMERAS April 2004

Putting It in Perspective

� RLR has become a national safety problem, with a societal cost estimated at $14billion per year.

� Motorists are more likely to be injured in crashes involving RLR than in other typesof crashes. Occupant injuries occurred in 45 percent of the RLR crashes, comparedto 30 percent in other crash types.

� According to a survey conducted by the U.S. Department of Transportation andAmerican Trauma Society, 63 percent of Americans witness a RLR incident morethan once a week. One in three Americans knows someone who has been injuredor killed because of a red-light runner.

Crashes resulting from red-light running are

much more likely to cause an injury or fatality

than other intersection crashes.U.S. Department of TransportationFederal Highway Administration

77

Using Red-Light Cameras to Reduce Red-Light Running (RLR)

Solution:Red-light cameratechnology canmake intersec-tions safer.The solution to the RLR probleminvolves a combination of engineering,education and enforcement measures.Research suggests that “intentional”red-light runners, who account for a sig-nificant percentage of red-light runners,are most affected by enforcementcountermeasures.

What are red-light cameras?Red-light cameras encompass a systemthat allows for automated enforcementof RLR. It includes embedded vehicledetectors wired to signal controllersthat can detect if a vehicle has enteredthe intersection when the signal is red.Some systems also record the speed ofthe vehicles as they approach and enterthe intersection. Roadside mountedcameras record images (either film ordigital) of the violation. Depending uponthe camera placement and agency’s pol-icy, front or rear images of the vehicleare processed.The images are reviewedat a central location and if the violationis confirmed by law enforcement, then acitation is issued to the owner of thevehicle. In some jurisdictions, the ownercan challenge the citation if he or shewas not the driver.

The usage of automated RLR enforce-ment is increasing with more than 90jurisdictions in 15 states deploying oneor more camera systems.

Successfulapplications:Researchdemonstratescrash reductionsBased on a literature review and juris-diction survey reported in the NationalCooperative Highway Research

Program Synthesis 310, Impact of RedLight Camera Enforcement on CrashExperience, a majority of jurisdictionsreported downward trends in RLR-related violations and crashes, especial-ly the more severe kind, because of red-light cameras. For example:

� In Fairfax, VA, violations werereduced by 41 percent after thefirst year of camera enforcement;

� San Francisco and Los Angeles, CArealized a 68- and 92-percentreduction in violations, respectively;

� In Charlotte, NC, RLR violationswere reduced by more than 70percent during the first year ofoperation; and

� In Oxnard, CA, the number ofcrashes at all signalized intersec-tions was reduced by 7 percentand the number of injury crasheswas reduced by 29 percent.

ProperImplementationof RLR CamerasThe primary purpose of RLR cameras isto reduce RLR violations and therebyreduce RLR-related crashes. RLR-cam-era programs should not be implement-ed to increase revenue from citations.According to the Federal HighwayAdministration’s Guidance for Using Red-Light Cameras, the following critical ele-ments should be considered whileinstalling red-light camera systems:

� Conduct an engineering studybefore considering camera installa-tion;

� Evaluate effective engineering andeducation alternatives before con-sidering photo-enforcement;

� Make sure the red-light cameraprogram is engineered andinstalled properly;

� Measure, document and makesafety results available;

� Ensure complete oversight andsupervision by public agencies;

� Avoid compensating vendorsbased on number of citations; and

� Include an ongoing photo-enforce-ment public education program.

Resources1. Engineering Countermeasures to Reduce Red-

Light Running. Washington, DC: ITE, 2003.http://safety.fhwa.dot.gov/rlr/rlrreport/RLRbook.pdf

2. Guidance for Using Red Light Cameras. ThisFHWA publication provides information tostate and local agencies on how to initiateand operate an appropriate red light cameraprogram. Call 202-366-5915 to orderPublications No. FHWA-SA-03-018, or visithttp://www.nhtsa.dot.gov/people/injury/enforce/guidance03/Guidancereport.pdf

3. Impact of Red Light Camera Enforcement onCrash Experience. This NCHRP synthesisexamines what impact camera enforcementhas had on crashes and crash severity, basedon published literature and information fromjurisdictions.http://gulliver.trb.org/publications/nchrp/nchrp_syn_310.pdf

CAMERAS April 2004 2

Automated

enforcement can

be an effective

and reliable

tool to help

reduce the number

of RLR violations

and associated

crashes.

IntroductionStudies included in the NCHRP 17-18 (3), Guidance for Implementation of the AASHTO StrategicHighway Safety Plan, as well as in other research by governmental entities have produced estimatesof crash reductions that might be expected if a specified improvement or group of improvementsare implemented.Three tables have been developed that attempt to summarize some of the avail-able information. Readers will note that, by and large, there may be little consensus regarding thevalue of crash reduction factors for a number of countermeasures.The transportation engineer-ing discipline needs to develop a base of statistically sound before-and-after studies for extendedperiods of time to overcome the deficit in countermeasure effectiveness data.

Use of the Tabular DataThe data in this briefing sheet represent a number of countermeasure effectiveness studies andincludes ranges of effectiveness realized from one or more sources. Readers are encouraged toobtain and review original source documents for more detailed information. It must be empha-sized that the potential effectiveness values, for expample percentage reduction in crashes, repre-sent order-of-magnitude estimates only. Traffic engineers need to consider site-specific environ-mental, geometric and operational conditions before making a judgment regarding those counter-measures that will be applied to an intersection.

Traffic engineers and other transportation professionals can use the information contained in thisbriefing sheet when the public or an elected or appointed official asks a question such as:

What is the range of solutions that might be considered at the signalized intersection of Mapleand Elm streets due to the high number of total crashes and left-turn crashes?”What low-costimprovements can be tried first? If these improvements do not give us a higher degree of safe-ty, what else can we try?

The countermeasure effectiveness tables in this briefing package include:

� Table 1: Signalization Countermeasures at Signalized Intersections. Specific cate-gories of countermeasures included in this table are signal timing and phasing improvements,signal hardware and combination signal and other improvements.

� Table 2: Geometric Countermeasures at Unsignalized Intersections. Specific cate-gories of countermeasures included in this table are left-turn treatments, right-turn treat-ments and other geometric improvements.

� Table 3: Signs/Markings/Operational Countermeasures (Applicability Notes forSignalized and/or Unsignalized Intersections). Specific categories of countermeasuresincluded in this table are: signs, pavement markings and modifications, and regulatory, lightingand operational improvements.

Toolbox ofCountermeasures and TheirPotential Effectiveness toMake Intersections Safer

1TOOLBOX OF COUNTERMEASURES April 2004


88

Toolbox of Countermeasures and Their Potential Effectiveness to Make Intersections Safer

TOOLBOX OF COUNTERMEASURES April 2004 2

Table 1:Signalization Countermeasures at Signalized Intersections

Numbers in [n] indicate references used

Numbers prior to the [n] represent the range of % crash reduction that might be expected from implementing a given improvement.




SIGNAL OPERATIONS IMPROVEMENTS

Interconnect/Coordinate Medium 15-17 [1] 25-38 [12] � � [2]Traffic Signals; Optimization

Increase/Modify Clearance Intervals Low 4-31 [1,9,10] 1-30 [1,9] � � [2]Improve Signal Timing (General) Low 10-15 [1] � � � �

Add Protected/Permissive LT Phase Medium 4-10 [1,9] 40-64 [1,9]Use Green Arrow/ Protected Left Low 3 [9] 98 [9] �

Turns/Movement Signal PhasingUse Split Phases Low 25 [11] � � �

Use Leading Pedestrian Interval Low 5 [8]Add Pedestrian Phase Medium 23-25 [1] 7-60 [1,8]Add Left-Turn Phasing to an Medium 23-48 [6, 12] 63-70 [1] 5 [8]

Existing Signal Provide Green Extension Variable � �

(Advance Detection)Install Signal Actuation Variable � �

Assume Slower Walking Speeds for Low � �

Pedestrian Signal TimingProvide Advance Warning of Signal Medium � � � �

Changes at Rural Signalized Intersections

Remove Signals from Late Night/Early Low 29 [9] 80 [9]Morning Flash

Consider Restricting Right-Turns- Low �

on-RedConsider Installation of Pedestrian Low �

Countdown Signals(incremental cost)

Consider Installation of Animated Low �

Eye Signals (Incremental cost)

SIGNAL HARDWARE

Install Larger (12-Inch) Signal Lenses Low 10-12 [1,9] 48 [9] � � � �

Install Flashing Beacon at Intersection Medium 30-38 [1]Install Flashing Beacon at Advance Medium 25-28 [1] � [2]

of IntersectionReplace Pedestal Mounted Signal High 28-43 [12] �

with Mast ArmInstall Backplates on Existing Signals Low 2-24 [1,9] 7-93 [1,5,9] � � � [2] �

Optically Programmed Signal Lenses 15-18 [1] �

Provide Louvers,Visors, Special Lenses Low � � �

so Drivers are able to View Signals only for their Approach

Upgrade Signal Controller Medium 20-22 [1 8, 11] � � �

Relocate/Shield Signal Hardware in Medium [6] � � �

Clear Zone. Signal Hardware Should Not Obstruct Sight Lines.

Install Additional Signal Heads Medium 10 [9] 42 [9] � � � �

Install More Overhead Traffic Signals High � � � � �

Provide Two Red-Signal Displays Medium � [2]within each Signal Head to IncreaseConspicuity of the Red Display

Use LED Traffic Signal Module. Medium � [2]Stripe for Left-Turn Lane within Low 26 [9] 66 [9]

Existing RoadwayRed T-Display Medium 9 [9] 36 [9]



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88Potential Effectiveness(Percentage Reduction)


COMBINATION SIGNAL AND OTHER IMPROVEMENTS

Construct Left-Turn Lanes with High � � �

Signal UpgradesLeft-Turn Lane, Signal and NO High 21-25 [1] 46-54 [1] �

Turn PhaseLeft-Turn Lane, Signal PLUS High 25-36 [1] 43-45 [1] �

Turn Phase Add Left-Turn Phasing AND Turn High 46-69 [12] � � �

Lanes to an Existing Signal Removal Signal, Develop a Program Low 50-53 [1] � �

to Identify and Remove Unwarranted Signals.

Install 12” Signal Heads and SIGNAL Low 11 [9] 36 [9]

Table 1 (continued) Signalization Countermeasures at Signalized Intersections

Table 2 (continued on page 4)

Table 2:Geometric Countermeasures at Unsignalized Intersections


Improvement Type/Special User Cost Total Right Angle Left Turn Rear-end Sideswipe OlderCrashes Driver

LEFT TURN TREATMENTS

Add Left-Turn Lane, No Signal Medium-High 25-41 [1,9] 50-86 [1,9]Provide Separate Left-Turn Lane, Medium 44/rural �

One Major Road Approach, and 33/urban [5]3-Leg Intersection.

Provide Separate Left-Turn Lane, Medium 28/rural �

One Major Road Approach, and 27/urban [5]4-Leg Intersection.

Provide Separate Left-Turn Lane, High 42 [5]2 Major Road Approaches

Provide Adequate Length Turn Lane Medium 15-30 [1,7,10] �

Provide Indirect Left Turns Variable � � �

Provide Offset Left Lanes Variable � � � � � [1]Provide Left-Turn Acceleration Lane Medium-High

at Divided Highway Intersections �

Add Continuous Left-Turn Lanes High � [1]

RIGHT-TURN TREATMENTS

Provide Right-Turn Lane, One Major Medium 14 [5, 10] �

Approach, on Rural 4-Lane, IntersectionExclusive Right-Turn Lanes,Two Major Variable 14-27 [5] �

Approaches, on Rural 4-Lane, IntersectionProvide Right-Turn Acceleration Lanes Variable � � �

Provide Longer Right-Turn Lane Variable �

Provide Offset Right-Turn Lane Variable � � � [1]Add Right-Turn Lane Medium 24-30 [1]




Improvement Type/Special User Cost Total Right Angle Left Turn Rear-end Sideswipe OlderCrashes Driver

OTHER/GEOMETRIC IMPROVEMENTS

Shoulder Bypass Lanes; Rural Intersections. Low �

Move Intersection Away from Curve. High 25 [1,7,8] � � �

Horizontal/Vertical Realignment High � [7]of Approaches.

Raised Medians Near Major Intersections. Medium-High 25 [6,1,7,8]Continuous Two-Way Left-Turn Lanes to High 30-40 [1,7,8] �

Separate Left Turn and Through TrafficConvert 4-Leg to Two, 2-T Intersections High 57 [5,10]Convert Two-T Intersections to One 4-Leg. High � [7]Close or Relocate High Risk Intersections Variable 100 [7]Full Width Paved Shoulders. No Shoulder Variable 2.8% per ft. of �

Width Less than 8 ft. additional shoulderwidth [7]

Install Splitter Islands on the Minor Road Medium NCOE [7]Approach where the Intersection or STOP Sign is not Visible to Motorists.

Remove Intersection Skew Angle (of less High 40-50, [1,10]than 80 degrees); Realign Intersection

Increase Curb Turning/Edge of Pavement Radii Medium 15-21 [1,7] � � [1]Widen Approaches to Handle Turns Medium [7] � �

Roundabouts at Appropriate Locations High 38,Total Crashes76, Injuries

90, Fatalities [7]Clear Sight Triangle on Stop or Yield Low � [7] �

Controlled ApproachesClear Sight Triangle in the Medians of Low � [7]

Divided Highways Near Intersections


Table 3:Signs/Markings/Operational Countermeasures Applicability

Noted for Signalized and/or Unsignalized Intersections

Table 2 (continued) Geometric Countermeasures at Unsignalized Intersections


Improvement Type Applicability Cost Total Right Rear Side- Pedestrian Red-Light OlderCrashes Angle End swipe Running Adults

SIGNS

Install SIGNAL AHEAD Sign Signalized Intersection Low 3-40 [7,9, 11] 35 [9] � � � [2]Install LEFT TURN Signal Sign Signalized Intersection Low � [2]Install SLIPPERY WHEN WET Sign Signalized Intersection Low � [2]Enhanced Signing and Delineation Unsignalized Intersection Low � [7] � �

Supplementary STOP Signs Unsignalized Intersection Low � [7] �

Mounted Over the RoadwayInstall YIELD TO PEDESTRIAN Sign Undefined Low 10 [8]

PAVEMENT MARKINGS/MODIFICATIONSInstall Raised Pavement Markings Undefined 6-13 [1] �

20-30 (Night)20-46 (Wet, Night)

Use Wider Pavement Markings Undefined �

Install Rumble Strips on Undefined 2-44 [1]; NCOE [7] �

Intersection Approaches



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88Table 3 (continued) Signs/Markings/Operational Countermeasures Applicability Noted for Signalized and/orUnsignalized Intersections



PAVEMENT MARKINGS/MODIFICATIONS (continued)

Resurfacing Undefined 7-59 [1];W, 40-54 [1]

Add Stop Bars/Crosswalks Signalized Intersection 10-25 [10] � � �

Install Raised Crosswalk Undefined 8 [8]Groove Pavement for Skid Resistance Undefined 1-65 [1]; 25 [11] �

Wet- 42-75 [1]Angled Median Crosswalk Undefined Medium 12 [8]Add Stop bars,Wider Stop Bar on Undefined 10-27 [1,9, 11,13] � [5]

the Minor Road Approach; and 47 [9]Short Segments of Centerlines

Move Vehicle Stop Line Farther Signalized Intersection Low �

Back from Crosswalk AND Add Sign STOP HERE FOR PEDESTRIANS

STOP AHEAD and STOP Messages Undefined Low 6 [9] � [5]on Pavement 30 [9]

Add Centerlines, Stop Bars and Unsignalized Low 45 [9] 67 [9]Replace 24 in. STOP Signs

Double Indicated STOP Signs Unsignalized Low 11 [9] 36 [9]Add Centerlines and Move Stop Unsignalized Low 29 [9] 24 [9]

Bars to Extended Curb Lines.Add Centerlines, Move STOP Bars Unsignalized Low 9 [9] 0 [9]

to Extend Curb Lines, and Add Double-Indicated STOP Signs

Provide Dashed Pavement Lining to Undefined Low � [1]Guide Left-Turning Vehicles Through Selected Intersections

Signed and Marked Crosswalks. Unsignalized Intersection Low 25-48 [1] �

For Greatest Effectiveness,Include Curb Ramps, Curb Extensions

Use Rumble Strips Prior to Rural Rural, Low 35 [8]STOP Signs Unsignalized Intersection

Rumble Strips and SIGNAL AHEAD Signalized Intersection Medium � [2]Warning Sign and Pavement Marking with Message SIGNALAHEAD

Replace YIELD Signs with STOP Signs Unsignalized Low 29 [9] 9 [9]

REGULATORY2-Way to Multi-Way Stop Unsignalized Intersection Low 53-74 [4,9,11] 84 [9] � �

Restrict/Eliminate RTOR Signalized Intersection Low 20-25 [1] � � �

Eliminate Parking that Restricts Undefined Low 8-90Sight Distance [1, 7, 11]

Restrict Driveways Near Unsignalized Intersection Low � [1,7]Intersections; Right Turn In and Signalized IntersectionOut Movements Only

Allow Left Turns In, but Prohibit Unsignalized Intersection Low � [1,7]Left Turns Out at Selected Access Signalized IntersectionPoints (Access Management)

Table 3 (continued on page 6)



References1. Agent, Kenneth R. et. Al. Development of

Accident Reduction Factors. Research ReportKTC-96-13. Kentucky Transportation CenterCollege of Engineering, June 1996.

2. Institute of Transportation Engineers.Engineering Countermeasures to Reduce Red-Light Running.Washington, DC: ITE, 2003.http://safety.fhwa.dot.gov/rlr/rlrreport/RLRbook.pdf

3. FHWA Older Driver Handbook.

4. Harwood, D.W., F. M. Council, E. Hauer,W. E.Hughes, and A.Vogt. Prediction of the ExpectedSafety Performance of Rural Two-Lane Highways,Report No. FHWA-RD-99-207.Washington,DC: Federal Highway Administration, 2000.

5. Institute of Transportation Engineers. TrafficSafety Toolbox: A Primer on Traffic Safety.Washington, DC: ITE, 1999.

6. NCHRP 17-18 (3). Initial Draft Compendiumof Strategies, Signalized Intersections, PhaseII. Draft April 29, 2002.

7. NCHRP, 500. Volume 5: A Guide for AddressingUnsignalized Intersection Collisions.http://gulliver.trb.org/publications/nchrp/nchrp_rpt_500v5.pdf

8. MetroPlan Orlando. Orlando Urban AreaArterial Pedestrian Crash Study. Orlando:MetroPlan Orlando, July 12, 2000.

9. Polanis, Stanley F. Low Cost SafetyImprovements. City of Winston-Salem, NorthCarolina, November 2003.

10. Retting. R. M. Greene. Influence of Traffic SignalTiming on Red-Light Running and PotentialVehicle Conflicts at Urban Intersections,Transportation Research Record 1595.Washington, DC:TRB, 1997.

11. SEMCOG. Traffic Safety Manual, SecondEdition. September 1997.http://www.semcog.org/TranPlan/TrafficSafety/assets/Safety_Manual.pdf

12. Thomas, Gary B. and Daniel J. Smith.Effectiveness of Roadway Safety Improvements,Final Report. Highway Division of the IowaDepartment of Transportation, CTREManagement Project 00-61, March 2001.

13. TEXDOT 1995.

Other ReferencesConsulted

Pedestrian-Bicycle Information Center Website. http://www.walkinginfo.org

South Dakota Department of Transportation.Development of South Dakota Accident ReductionFactors: SD 98-13,August 1998.http://www.state.sd.us/Applications/HR19ResearchProjects/Projects/SD1998_13_final_report.pdf

Table 3 (continued) Signs/Markings/Operational Countermeasures Applicability Noted for Signalized and/orUnsignalized Intersections



LIGHTING

Improve Visibility of the Intersection Unsignalized Intersection Medium 19-75 [1, 7, 8] � � �

by Providing Lighting Signalized Intersection Night- 18-70 [1]Improve Visibility of the Existing Undefined Medium 25-50 [1]

Rural Intersections and Urban N-42-50 [1] �

Corridors by Providing Lighting

OPERATIONAL

Add Signal to a Unsignalized Unsignalized High 20-45 [1,9] 68 [9]Intersection when Warranted

Add Raised Medians Near Undefined 25 [1,10,12] �

IntersectionsInstall Flashing Beacons Unsignalized Intersection � [1] �

Improve Access Control Near Unsignalized Intersection � [1]Intersections Signalized Intersection

Refuge Islands Undefined 56 [8]Pedestrian Overpasses/Underpasses Unsignalized Intersection High 13 [8]

Midblock 90-95 [1]Mid-block Traffic Signal Midblock High 52 [8]Far-side Bus Stops Unsignalized Intersection

Signalized Intersection 1 [8]Install Raised Medians Unsignalized Intersection Medium 69 [8]

Signalized IntersectionSpeed Reduction and Enforcement Unsignalized Intersection High 70 [8]

Signalized IntersectionCut Back Vegetation, Embankments Unsignalized Intersection [5]

as Far as Possible at Existing Stop- Signalized IntersectionSigned Controlled Intersections


Although intersections represent a very small percentage of U.S. surface road mileage, more thanone in five pedestrian deaths is the result of a collision with a vehicle at an intersection.Annually,an average of 5,381 pedestrians died in traffic crashes between 1990 and 2002. 1

OverviewThe Year 2002 National Highway Traffic SafetyAdministration’s pedestrian crash facts are as follows:

� 4,808 pedestrians were killed;� 1,046 pedestrians, or 22 percent, of all pedestri-

ans were killed at intersections;� 71,000 pedestrians were injured;� 31,000 pedestrians, or 44 percent, of all pedes-

trians were injured at intersections;� A pedestrian is killed or injured in an inter-

section traffic crash every 16 minutes;� 13 percent of pedestrian fatalities at intersec-

tions occur at night (between the hours of 6:00p.m. and 6:00 a.m.);

� Pedestrians involved in crashes are more like-ly to be killed as vehicle speed increases. Thefatality rate for a pedestrian hit by a car at 20mph is 5 percent. The fatality rate rises to 80percent when vehicle speed is increased to 40mph; 2

� People aged 70 and older account for 17 percent of all pedestrian fatalities;� People aged 65 and older have about 2.5 as many pedestrian deaths per 100,000 people as

younger groups; and� 36 percent of pedestrian deaths among those aged 65 and older occurred at intersections.

This compares to 20 percent for people of other ages.

Pedestrian Safety Problems atIntersectionsTypes of hazardous intersections for pedestrian crossings include high-volume, high-speed andmulti-lane intersections with complex signal phasing or without any traffic control at all.

Pedestrians are at risk even at simple STOP- or YIELD-sign intersections because of the commondisregard of traffic control devices by both motorists and pedestrians.

Roadways need to be designed to accommodate the needs of all road users. Roadway modifica-tions that include widening streets, adding lanes and using traffic engineering solutions thatincrease vehicular efficiency can decrease pedestrian safety if not properly considered.

Many pedestrians, especially in large urban areas, violate pedestrian traffic control and place them-selves at risk for collisions with motor vehicles. 3 About one-third of fatal crashes involving pedes-trians are the result of pedestrians disobeying intersection traffic control or making misjudgmentswhile attempting to cross a street. 4

Pedestrian Safety atIntersections

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Pedestrian Safety at Intersections

Pedestrian and driver traffic controlviolations generally receive low levels ofenforcement.

Intersection reconstruction projectsand traffic control installations canincrease the distance that one mustwalk to cross at an intersection.Intersection signal timings may be tooshort to permit safe intersection cross-ing. Assumptions of walking speeds forsignal timing may be too fast for manypedestrians to cross to the other sideof the curb.Also, there appears to be apoor understanding of pedestrian signaldisplays by pedestrians.

Crash data consistently show that crash-es with pedestrians occur far more oftenwith turning vehicles than with straight-through traffic. Left-turning vehicles aremore often involved in pedestrian colli-sions than right-turning vehicles, partlybecause drivers are not clearly able tosee pedestrians on the left. 5

Right-turn-on-red (RTOR) can poten-tially contribute to pedestrian crashesbecause it creates conflicts betweenpedestrians and motor vehicles and canreduce pedestrian opportunities tocross intersections, even though pedes-trians have the right-of-way over theright-turning vehicles.

Pedestrian visibility to drivers is worseduring hours of darkness, especially inareas where there is poor lighting onthe road.This is a common shortcomingof rural and suburban intersections.Studies of pedestrian and driver reac-tions indicate that pedestrians generallyperceive that they are visible to driversbefore they are visible.

Pedestrian SafetyCountermeasures The following section provides possiblepedestrian safety countermeasureswithin the following categories: cross-walk improvements, intersection design/physical improvements, intersectionoperations and signal hardware/tech-nology. Modifications to pedestrian con-trol devices from the 2003 Manual onUniform Traffic Control Devices (MUTCD)are also included.

Crosswalk Improvements

� Use a ladder or cross-hatched pat-tern that is more visible tomotorists;

� Use “Pedestrian Crossing” warn-ing signs with pedestrian-actuatedflashing beacons, which alertoncoming traffic to pedestrians inthe crosswalk;

� Move the vehicle STOP line far-ther back from crosswalk ANDadd STOP HERE FOR PEDESTRI-ANS sign;

� Install raised crosswalks;� Sign and mark crosswalks. For

greatest effectiveness, include curbramps or curb extensions;

� Use in-pavement lights to alertmotorists to the presence of apedestrian crossing or whensomeone is preparing to cross thestreet. Transportation profession-als should review the new Chapter4L of the 2003 MUTCD that pro-vides guidance on the use of in-pavement lights at crosswalks;

� Consider using MUTCD Sign R1-6: STOP FOR PEDESTRIANS orYIELD TO PEDESTRIANS signscan be placed at crosswalks with-out signals in central business dis-tricts and other areas of highpedestrian activity to reinforceand remind drivers of the lawsregarding the right-of-way ofpedestrians; and

� MUTCD Sign R1-5(a): YIELDHERE TO PEDESTRIANS signs arefor use in advance of unsignalizedmarked mid-block crosswalks.

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R1-5(a)

R1-6



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99Intersection Design/Physical Improvements

� Install barriers such as fences orshrubs to discourage pedestri-ans from crossing at unsafe loca-tions;

� Install bulb-outs at intersectionsto reduce pedestrian crossingdistance;

� Provide wide refuge islands andmedians;

� Construct pedestrian overpass-es/underpasses;

� Install raised medians; and� Reduce corner radii.

Intersection Operations

� Reassess traffic signal operations,including consideration of pedes-trian walking speeds/pedestriansignal timing and pedestrian-onlyphasing Consider restricting right-turn-on-red (RTOR);

� Illumination;� Mid-block traffic signal; and� Far-side bus stops.

Signal Hardware/TechnologyConsider installation ofPedestrian CountdownSignals

2003 MUTCD Section 4E.07Countdown Pedestrian Signals A pedestrian interval countdown dis-play may be added to a pedestrian sig-nal head in order to inform pedestri-ans of the number of seconds remain-ing in the pedestrian change interval.

Consider installation ofAnimated Eye PedestrianSignal

Animated eyes are intended for useat pedestrian crosswalks as an alter-native to conventional pedestrian sig-nals. Animated eye displays mayencourage pedestrians to look forturning vehicles traveling on an inter-secting path by including a prompt aspart of the pedestrian signal. Theprompt is a pair of animated eyes thatscan from side to side at the start ofthe WALK indication.

Accessible PedestrianSignals

2003 MUTCD: Section 4E.06 AccessiblePedestrian Signals (APS)The installation of APS at signalizedlocations should be based on an engi-neering study, which should considerthe following factors: (1) potentialdemand for accessible pedestrian sig-nals; (2) a request for accessiblepedestrian signals; (3) traffic volumesduring times when pedestrians mightbe present, including periods of low-traffic volumes or high turn-on-redvolumes; (4) complexity of traffic sig-nal phasing; and (5) complexity ofintersection geometry. When usingAPS, the pedestrian signal must bevisible and any push-buttons must beaccessible with audible locator tonesfor people with visual disabilities.

Pedestrian Intervals andSignal Phases

2003 MUTCD Section 4E.10 The pedestrian clearance time shouldbe sufficient enough to allow a cross-ing pedestrian, who left the curb orshoulder during the WALKING PER-SON signal indication, to travel at awalking speed of 4 ft. per second to

make it to at least the far side ofthe traveled way or to a medianof sufficient width for pedestri-ans to wait. Where pedestrians,who walk slower than 4 ft. per sec-ond or use wheelchairs, routinely usethe crosswalk, a walking speed of lessthan 4 ft. per second should be con-sidered in determining the pedestrianclearance time.

The Three E-Approach:Engineering Alone is NotSufficient

Improved pedestrian safety at inter-sections requires coordination amongpublic authorities, professional engi-neers, media, education experts andvehicle designers to reduce both thenumber and severity of pedestriancollisions. Pedestrian safety cannot beimproved by traffic engineering alone;it is a partnership between the driver,pedestrians, parents of young chil-dren, schools, police departments andothers.

From an enforcement perspective, weneed to ensure motorist compliancewith traffic control devices, postedspeeds and pedestrian safety laws.Pedestrians need to understand andobey intersection traffic control.Pedestrians need to make themselvesmore visible during evening and night-time hours. One way to do this is towear reflective clothing and acces-sories.All partners need to develop asustained and comprehensive inter-section safety public awareness cam-paign that reaches both motoristsand pedestrians.

SamplePedestrianSafetyPrograms/Tools Federal HighwayAdministration'sPedestrian SafetyCampaign Planner

This toolkit contains outreach mate-rials that states and local jurisdictionsand communities can customize and

use locally.The threefold purpose of thecampaign is to (1) sensitize drivers tothe fact that pedestrians are legitimateroad users and should always beexpected on or near the roadway, (2)educate pedestrians about minimizingrisks to their safety and (3) developprogram materials to explain orenhance the operation of pedestrianfacilities, such as crosswalks and pedes-trian signals.http://safety.fhwa.dot.gov/pedcampaign/index.htm

Federal HighwayAdministration’s CrashGroup/GeneralCountermeasure Matrix

This tool identifies potential solutionsfor use by safety practitioners. Thismatrix is particularly helpful as aresource of potential engineering coun-termeasures, which may be implement-ed at a location to address a particularpedestrian crash type.http://safety.fhwa.dot.gov/saferjourney/Library/matrix.htm

Federal HighwayAdministration’s Pedestrianand Bicycle Crash AnalysisTool (PBCAT)

The Pedestrian and Bicycle CrashAnalysis Tool is a crash-typing softwareintended to assist state and local pedes-trian/bicycle coordinators, planners andengineers with improving walking andbicycling safety through the developmentand analysis of a database containingdetails associated with crashes betweenmotor vehicles and pedestrians or bicy-clists.The software allows a person to:

� Determine the crash type througha series of on-screen questionsabout the crash, crash location andmaneuvers of the parties involved;

� Customize the database in termsof units of measurement, variablesand location referencing, as well asimport/export data from/to otherdatabases;

� Produce a series of tables andgraphs defining the various crashtypes and other factors associatedwith the crashes, such as age, gen-der and light conditions; and

� Recommend countermeasureslinked to specific bicycle andpedestrian crash types and relatedresource and reference informa-tion.

This tool can be ordered free of chargethrough the following Web site.http://www.walkinginfo.org/pc/order. htm.

ITE/Partnership for A Walkable America

Pedestrian Project Awards

ITE, in cooperation with thePartnership for a Walkable America anda grant from the Robert Wood JohnsonFoundation, conducted a PedestrianProject Award Program in 2003. Morethan 106 submittals were received in sixcategories: safety, facilities, education,policy, partnerships and elderly andmobility impaired. Each submission,including the program description forboth the winners and all nominees, hasbeen digitized and is included on ITE’sTransportation and Active Living WebSite as follows:http://www.ite.org/activeliving/index.asp.

The 2003 Pedestrian Awards were givento the following organizations:

� Safety. City of Boulder Coloradoand Short Elliott Hendrickson

� Facilities. New York Departmentof Transportation and VollmerAssociates LLP.

� Education. Utah Department ofHealth and the Utah HighwaySafety Office for the GreenRibbon Month project.

� Policies. The WisconsinDepartment of Transportation forthe Wisconsin Pedestrian PolicyPlan 2020.

� Partnership. City CouncilMember Richard Conlin and FeetFirst for Seattle’s PedestrianSummer project.

� Elderly and Mobility Impaired.City of Portland, et. al.

References1. NHTSA, FARS, 2002.

2. Insurance Institute for Highway Safety, StatusReport 35 (5), May 13, 2000.

3. Fatality Facts, Pedestrians 2002, InsuranceInstitute for Highway Safety.

4. NHTSA, FARS, 2000.

5. Insurance Institute for Highway Safety, Q&A:Pedestrians, December 2000.

6. Zegeer, Charles V. et. al. Safety Effects ofMarked vs. Unmarked Crosswalks atUncontrolled Locations. Executive Summary andRecommended Guidelines. FHWA RD-01-075,February 2002.ht tp : / /www.wa lk ing in fo.org /pd f / r&d/crosswalk_021302.pdf

Additional Resources

FHWA. The Effects of Innovative PedestrianSigns at Unsignalized Locations: A Tale ofThree Treatments. REPORT NO. FHWA-RD-00-098 August 2000.http://www.walkinginfo.org/task_orders/to_11/3signs00.pdf

Florida Department of TransportationPedestrian and Bicycle Research.http://www11.myflorida.com/safety/ped_bike/ ped_bike_reports.htm

Institute of Transportation Engineers.Alternative Treatments for At-Grade PedestrianCrossings, Item LP-629. 2001, 200 pp., ISBNNo: 0-935403-61-2.

Institute of Transportation Engineers. Designand Safety of Pedestrian Facilities, Item RP-026A. 1998, 115 pp.

National Center for Statistics and AnalysisAdvanced Research and Analysis. DOT HS809 456 Technical Report: PedestrianRoadway Fatalities,April 2003.http://www-nrd.nhtsa.dot.gov/pdf/nrd-30/NCSA/ Rpts/2003/809-456.pdf

Pedestrian and Bicycle Information Center.http://www.walkinginfo.org/

U.S.Access Board.http://www.access-board.gov/

Walkinginfo.org Accessible Pedestrian SignalsHome Page.http://www.walkinginfo.org/aps/home.cfm



The ProblemDriving within intersection environments requires complex speed-distance judgments under timeconstraints.This scenario for intersection operations can be more problematic for older driversand pedestrians than for their younger counterparts. For the calendar period from 1997 to 2002,fatalities at intersections for drivers aged 65 and older ranged from 2,500 to 2,950 each year.

According to the National Highway Traffic Safety Administration, older drivers are more likely thandrivers in their 30s, 40s, or 50s to be involved in traffic crashes, and they are more likely to bekilled in traffic crashes. The number of Americans 65 years of age and older is expected to dou-ble between 2000 and 2030.Americans are living longer and driving longer.Together these trendssuggest that the number of older drivers killed on U.S. streets and highways will grow. 1

The AAA Foundation for Traffic Safety recently released a report entitled, “Older DriverInvolvement in Injury Crashes in Texas: 1975 to 1999.” This study evaluated 25 years of police-level crash data from nearly 4 million injury crashes in the state of Texas. Crashes were analyzedto determine the association between driver age and four factors: fragility—the likelihood of deathamong drivers involved in injury crashes; illness—the likelihood that drivers were ill or sufferingfrom some other physical defect at the time of their crashes; perceptual lapses—the likelihoodthat drivers involved in crashes failed to yield the right-of-way or disregarded traffic signs or sig-nals and left turns—the likelihood that left turns were involved in injury crashes. Readers areencouraged to review the entire research report which is available in PDF on the AAA FoundationWeb site.

Three different age thresholds were used in defining the older population. Group I, persons are65 years of age and older; Group 2, persons 75 and older; and Group 3, persons 85 and older.Drivers aged 55 to 64 constituted the comparison group in the analyses. When the analyses con-trolled for crash type (single-vehicle vs. multiple vehicle), population density (rural vs. urban), driv-er sex (male vs. female), light condition (daylight vs. darkness) and intersection relatedness, driv-ers in the three older age categories, compared with drivers aged 55–64, were found to be morelikely to die in injury crashes:

� Drivers 65+ years of age were 1.78 times as likely to die;

� Drivers 75+ years of age were 2.59 times as likely to die; and

� Drivers 85+ years of age were 3.72 times as likely to die.

In addition, all three older person groups were more likely to (1) have been ill or suffering someother physical defect at the time of their crashes, (2) have suffered perceptual lapses that con-tributed to their crashes (such as failure to yield the right-of-way or disregarding signs or signals)and (3) have been involved in left-turn crashes.

Older Drivers atIntersections

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Older Drivers at Intersections

Figure 1 shows a comparison of totalfatalities to intersection fatalities for theyears 2000 through 2002 for three agegroups: 64 and younger, ages 65 to 74and for ages 75 and older. As shown,when considering total fatalities, thepercentage of intersection fatalitiesinvolving older people in both the 65 to74 and 75 and older age groups areclearly overrepresented.

Project PlanningConsiderationsDuring the planning stage for each proj-ect involving new construction orreconstruction of an existing intersec-tion, practitioners should seek answersto the following four questions:

� Is there a demonstrated crashproblem with older drivers orpedestrians?

� Has any aspect of design or oper-ations at the project location beenassociated with complaints to localor state officials from older roadusers or are you aware of a poten-tial safety problem, either throughpersonal observation or agencydocumentation, applying your ownengineering judgment?

� Is this project located on a directlink to a travel origin or destina-tion for which older people con-stitute a significant proportion ofcurrent users?

� Is the project located in an areaexperiencing an increase in theproportion of residents aged 65and older?

� Is this project located on a directlink to a travel origin or destina-tion for which older people con-stitute a significant proportion ofcurrent users?

� Is this project located in an areathat will constitute a significantproportion of future older people,perhaps where there is a plannedmedical center or senior housingproject nearby?

EngineeringSolutions To MakeIntersectionsSafer for OlderDrivers The solutions to reduce older drivercrashes incorporated into this briefingsheet have been extracted from theFHWA Older Driver Design Handbook.These solutions should benefit all roadusers, not just older people. It isacknowledged that intersection proj-ects may have constraints, such as highconstruction costs, the need for addi-tional right-of-way, local access manage-ment requirements, sight distance andother issues that may preclude the useof the suggested solutions. In all cases,professional engineering judgementmust be used to validate the use ornon-use of a particular solution set.

Design

� Use a minimum receiving lanewidth of 12 ft. accompanied, wher-ever practical, by a minimum 4-ft.shoulder;

� Use positive offset of opposingleft-turn lanes to increase the safe-ty for older drivers who, as agroup, do not position themselveswithin the intersection before ini-tiating a left turn;

� In the design of new facilities orredesign of existing facilities where

right-of-way is not restricted, allintersecting roadways should meetat a 90-degree angle.Where right-of-way restrictions are present,intersecting roadways should meetat an angle of no less than 75degrees;

� Where roadways intersect at 90degrees and are joined with a sim-ple radius curve, provide a cornercurb radius in the range of 25 ft. to30 ft. to: (a) facilitate vehicle turn-ing movements, (b) moderate thespeed of turning vehicles, and (c)avoid unnecessary lengthening ofpedestrian crossing distances; and

� For left- and right-turn lane treat-ments, provide raised channeliza-tion with sloping curbed medians.

Signs

� Install larger (oversized) regulato-ry and warning signs;

� Use signs fabricated using highintensity retroreflective sheeting;

� Use redundant street-name sign-ing for major intersections with anadvance street-name sign placedupstream of the intersection at amidblock location;

� Increase sign lettering size forstreet names, directional signingand advance intersection signing;

� Install more overhead-lightedadvance signing prior to majorintersections. Include overheadlane-use control signs to help driv-

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Figure 1

Source: Fatal Analysis Reporting System (FARS). 2000, 2001, and 2002.



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1010ers get into the proper lane inadvance of the intersection;

� Use overhead-mounted street-name signs as a supplement topost-mounted street-namesigns;

� When using advance intersec-tion warning signs, accompanythe signs with an advance street-name plaque;

� When different street names areused for different directions oftravel on a crossroad, the namesshould be separated and accom-panied by directional arrows onboth advance midblock andintersection street-name signs;

� Where appropriate (e.g. dual-turn lanes or where a throughlane becomes a turn-only lane)use lane-use control signs atintersections on a signal mastarm or span wire;

� Where appropriate, use theLEFT TURN YIELD ONGREEN with protected-per-mitted mode left-turn signalphases;

� Where practical, use a redun-dant upstream LEFT TURNYIELD ON GREEN sign atthe start of the left-turn lane, inaddition to using the same signadjacent to the signal face, toremind left-turning drivers ofthe requirement to yield tooncoming traffic before turningon green.

Pavement Markings

� Treat the median and islandcurb-sides and curb horizontalsurfaces with retro-reflectorizedmarkings and maintain them at aminimum luminance contrastlevel;

� Provide more visible anddurable pavement markings;

� Use retroreflective raised pave-ment markings;

� Use wider pavement markings;

� Use transverse pavement strip-ing or rumble strips upstream ofstop-controlled intersectionswhere there may be sight

restrictions, high approachspeeds, or a history of ran-stop-sign crashes. This treatment canalso be used in rural areaswhere a stop sign is encoun-tered after a long distance withno traffic control devices;

� Delineate median noses usingretroreflective treatments toincrease visibility and improvedriver understanding; and

� Where appropriate (e.g. forexclusive left- or right-turnlanes) use lane-use arrow pave-ment markings at appropriatedistances in advance of a signal-ized intersection.

Traffic Signal Operations

� Where minimum sight-distancescannot be achieved or where apattern of permitted left-turncrashes occurs, eliminate permit-ted left turns and use protected-only left-turn operations;

� Consider the use of a separatesignal face to control turningphase versus through move-ments;

� Use a leading protected left-turnphase wherever protected left-turn signal operation is imple-mented as opposed to a laggingprotected left-turn phase;

� Consider the use of a leadingprotected left-turn phase wher-ever protected-only left-turn sig-nal operation is implemented asopposed to a lagging protectedleft-turn phase. Lagging left-turnoperations, however, are morebeneficial for reducing vehicu-lar/older pedestrian conflictssince the pedestrian crossing isnormally completed before thebeginning of the lag-left greenarrow display;

� Use of red left arrows instead ofa circular red indication at leftturn signals;

� To accommodate age differencesin perception-reaction time, usethe yellow change interval andall-red clearance interval formu-lae in the Institute ofTransportation Engineers’ publi-

cation entitled, Traffic EngineeringHandbook, Fifth Edition; and

� Assume slower walking speedsfor signal-clearance timing in therange of 3.5 feet per second ifactual crossing times are notavailable. Time the clearanceinterval for a full crossing, or to amedian, but not just to the mid-dle of the farthest lane.

Traffic Signal Hardware

� Install larger (12 in.) signal lenses;

� Consistently use backplates withtraffic signals on all roads withoperating speeds of 40 mph orhigher. The use of backplateswith signals on roads with oper-ating speeds lower than 40 mphshould be used where there maybe special factors such as sunglare, a potential for wrong-waymovements and high nighttimepedestrian volumes;

� Conduct regular cleaning of lamplenses and replace lamps whenoutput has degraded by 20 per-cent or more from peak per-formance for all fixed lightinginstallations at intersections;

� Install additional signal heads;

� Install more overhead traffic sig-nals; and

� Consider using post-mountedsignals (sometimes called “sec-ondary,” “low level” and “far-sideleft signal heads”) to accommo-date left-turn drivers waiting inthe intersection to turn (permis-sive-only). Older drivers some-times cannot easily view an over-head signal (which is usually totheir right) at the same time theyare looking for gaps in opposingtraffic, especially if the overheadsignals are strung on a diagonalspan wire.

Right-Turns-on-Red (RTOR)

� Where a RTOR is prohibited,use more than one NO TURNON RED sign. A supplementalNO TURN ON RED signshould be placed on the over-head mast arm and at a location

on either the near or oppositeside of the intersection where itwill be most conspicuous; and

� At skewed intersections wherethe approach leg to the left inter-sects the driver's approach leg atan angle of less than 75 degrees,prohibit RTOR.

ResourcesFHWA. Older Driver Highway Design Handbook.January 1998. FHWA. Publication FHWA-RD-97-135.http://ntl.bts.gov/DOCS/older/home/index.html

Griffin, Lindsay F. III. Older Driver Involvement inInjury Crashes in Texas: 1995-1999. AAAFoundation for Traffic Safety, February 2004.http://www.aaafoundation.org.pdf/OlderDriverInvolvementInInjuryCrashes.pdf

ITE Traffic Engineering Handbook, 5th Edition.1999.

MUTCD: http://mutcd.fhwa.dot.gov.



IntroductionThe design and operation of intersections often fail toinclude features for good pedestrian access and safety,including consideration of people with visual andmobility disabilities. The pedestrian system must beusable for pedestrians of all ages and capabilities andmust provide safe crossing intersections for older peo-ple and young children.

The pedestrian system has traditionally been designedfor people who are mentally and physically agile, withgood stamina, vision and hearing. However, 20 percentof the U.S. population has a disability and 70 percentof the population will have a permanent or temporarydisability in time.

The Americans with Disabilities Act (ADA) has minimum design standards that are to be appliedto all public environments and this includes the public right-of-way.These standards, the Americanswith Disabilities Act Accessibility Guidelines (ADAAG), are the foundation for designing all pedes-trian environments, and better design practices are encouraged to be applied whenever possible.Pedestrian accessibility enhancements will not only benefit people with disabilities; they will ben-efit able-bodied pedestrians as well. Examples include curb ramp improvements that will assistpeople pushing carts or strollers and placing the WALK push buttons in a place that is accessibleand easily understandable for all intersection users.

Entities are encouraged to design and set codes beyond the minimum standards to facilitate accessfor a wider spectrum of people—they may not design below the standards. An entity is stillresponsible for making the features/facility accessible if a specific standard has not been adoptedfor that feature/facility.The nondiscrimination requirements for usability by people with disabilitiesin ADA are the overarching regulations that must be applied. It is critical for transportationproviders to understand the details and principals for accessible design in order to apply goodengineering judgment in difficult design situations. Pedestrian facilities with physical barriers, unus-able sign and signal information, gaps in the system and poorly designed features have critical safe-ty implications for people with disabilities and may leave them stranded and unable to get to theirdestinations.

Challenges for Engineers and DesignersFor pedestrians with disabilities, intersections prove a special challenge:

� Often the walking speed (generally set at 4 ft. per second) used for timing clearance phasesis not sufficient for people who are elderly or have disabilities, leaving them stranded in theintersection when the traffic signal changes;

� At intersections, turning vehicles and the speed at which they travel pose the greatest threatto pedestrians, and often the motorist’s attention is focused on other motorists; and

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Pedestrian Design for Accessibility Within the Public Right-of-Way

� Right-turn-on-red, roundabouts andchannelized right-turn lanes andother features designed to movetraffic more quickly can be haz-ardous for people with visual dis-abilities, who rely on the sounds oftraffic stopping and surging to judgeadequate gaps in traffic and WALKphases. The surging and stoppingcues at traditional intersections arenot present at many of the inter-section designs that have beeninstalled during the past two tothree decades, and if unable to rea-sonably judge crossing gaps, it isnearly impossible for people withvisual disabilities to cross the streetwith an assured amount of safety.

Questions to AskDuring ProjectDevelopment Designing for accessibility is largely amatter of common sense on the part ofthe designer or engineer, once there isawareness and understanding. It meansunderstanding the capabilities of users(children, elderly, people with cognitive,visual and mobility disabilities) andknowing how a facility should performfor all pedestrians.

Some of the questions to ask are:� Are the sidewalks passable by peo-

ple using wheelchairs, walkers andstrollers?

� Are crosswalks accessible?� Are there curb ramps (two per cor-

ner where practical)?� Do the ramps comply with ADA

specifications (critical design aspectsare the presence of a level platformat the top of the ramp, cross-slope

of the ramp and wheelchair traps atthe base of the ramp)?

� Is the ramp located in the pathpedestrian travel (i.e., do peoplewanting to use the ramp need todivert from the most direct path)?

� Is the push button of an actuatedpedestrian traffic signal accessible?

� Does it have a locator tone for peo-ple who are blind?

� Is the button proximate to thecrosswalk?

� Is it clear which crosswalk the but-ton actuates?

� Is the button located within reachof a wheelchair user or child?

� Are there non-visual cues that alertpedestrians to when they are leavingthe sidewalk and entering the street(examples are curb, lip of an ADAramp, or other tactile surface)?

� Is there an alternate route forpedestrians at construction sites?

� Are there cues at the site giving aperson using a white cane the infor-mation that is needed to knowthere is a sidewalk closure or openpit?

� Does the information give cues onhow to navigate safely around thesite and not into the construction?

� Is there a wheelchair ramp at thesite for users to navigate to thealternate route?

� Can pedestrians (especially a per-son with low vision) see the pedes-trian signal across the street?

� Is the pedestrian signal located onthe same pole as the vehicle indica-tion for conflicting movements(normally left and right turns) sothat pedestrians understand vehicleconflicts and visa versa?

� Is the pedestrian signal located onthe inside edge of the crosswalk sothat a truck stopped at the inter-section will not obstruct it?

� Are pedestrian signs easy to under-stand and interpret?

� Are there design features that cre-ate special challenges for visuallyimpaired pedestrians (examples:right-turns-on-red, right-slip lanes,or roundabouts without controlledcrossings)?

ReferencesFor more information on the safeaccommodation of pedestrians withdisabilities, refer to the following publi-cations and Web sites for resources:

1. Accessible Design for the Blind. Research,guidance and instructional materials on theuse of Accessible Pedestrian Signals (APS) anddetectable warnings,http://www.accessforblind.org

2. Barlow, Janet M., Billie Louise and Lee S.Tabor, AIA. NCHRP 3-62: Accessible PedestrianSignals: Synthesis and Guide to Best Practices,Final Report. May 2003.http://www.walkinginfo.org/aps/pdf/APS-Synthesis.pdf

3. Barlow, Janet, Pat Cannon, Dan Dawson, et. al.Building a True Community: Final Report: PublicRights-of-Way Access Advisory Committee,for the U.S. Access Board, February 2001.http://www.access-board.gov

4. Bentzen, Billie Louise and Lee S. Tabor, AIA.Accessible Pedestrian Signals. Work performedin support of the U.S. Access Board underContract No.PD-97-0772,August 1998.http://www.access-board.gov/research&training/pedsignals/pedestrian.htm

5. Bentzen, Billie Louise PhD, Janet M. Barlow,COMS and Lee S. Tabor. Detectable Warnings:Synthesis Of U.S. And International Practice. May2000.http://www.access-board.gov/publications/DW%20Synthesis/report.htm

6. FHWA. Designing Sidewalks and Trails for Access:Best Practices Guide Part II of II.http://www.fhwa.dot.gov/environment/side-walk2/index.htm

7. FHWA.Manual on Uniform Traffic Control Devices(MUTCD) provides the standards for trafficcontrol devices and included information onAccessible Pedestrian Signals (APS), Chapter4E and Temporary Traffic Control Elements,Chapter 6D, http://mutcd.fhwa.dot.gov

8. ITE. Traffic Control Device Handbook.Washington, DC: ITE, 2001. Pedestrians,Chapter 13.

9. Noyce,David A. Ph.D., P.E. and Janet M.Barlow,C.O.M.S. Interfacing Accessible Pedestrian Signalsand Traffic Signal Controllers.April 2003.http://www.access-board.gov/research&training/APS/report.htm


Research indicates that driver error may account for approximately 90 percent of all crashes.While advances in automotive safety and highway design continue to improve, the one componentthat has not changed is the driver. Understanding how drivers and all roadway users interact with-in an intersection environment is fundamental to improve roadway safety and save lives.

Driver Attention and Decision-Making Negotiating intersections is one of the most complex and demanding tasks a driver faces.To suc-cessfully execute a vehicle maneuver through an intersection, the driver must assimilate the infor-mation, make a decision and execute the desired action. One limitation is that humans are serialprocessors and the cognitive task-load at intersections can be quite large. Common items a driv-er must consider when approaching an intersection include:

� Monitoring and adjusting speed;� Maintaining lane position;� Being aware of other vehicles;� Attending to signals or signs;� Scanning for pedestrians, bicyclists, people in wheelchairs and blind or visually-impaired people;� Decelerating for a stop;� Searching for path guidance; and� Selecting proper lane.

Given the short time drivers have to process a large amount of information, it is imperative thatdesigners and engineers provide clear and accurate information to drivers to help them navigatean intersection.

Vision is the most important information reception characteristic of drivers. Features of humanvision are tied to specific roadway design elements as illustrated in Table 1.

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Table 1:Human Vision Characteristics as Related to

Roadway Elements

Visual Characteristic Related Roadway Element(s)

Visual Acuity. Ability to see small details clearly. Sign size; reading distant traffic signsContrast Sensitivity. Seeing objects that are similar in Pavement markings and delineation;brightness to their background. detection of dark clothed pedestrians at nightColor Vision. Discrimination of different colors. Sign and signal design and retroreflectivityVisual Field/Peripheral Vision Sign placement, signal placement; seeing a bicycle

approaching from the leftScan Patterns Sign placement, delineation treatmentsMotion Judgment/Angular Movement. Seeing objects School zones, highway railroad crossings;moving across the field of view. Judging the speed of cars crossing our path of travelMovement in Depth. Detecting changes in visual image size. Judging the speed of an approaching vehicle Visual Illusions Guide signs, pavement markingsDepth Perception. Judgment of the distance of objects. Passing on two-lane roads with oncoming trafficEye Movement. Changing the direction of gaze. Scanning the road environment for hazardsGlare Sensitivity. Ability to resist and recover from the Reduction in visual performance due to headlight glareeffects of glare

Human Factors Issues in Intersection Safety

Driver ErrorPerceptual failures account for a largeportion of driver errors. These caninclude such items as “looked but failedto see,” visual obstructions, reduced vis-ibility due to environmental factors, poorjudgment of speed and/or distance andlow conspicuity of target. However dis-traction, misinterpretation of informa-tion and driver impairment are alsomajor contributing factors. Intersectionsthemselves present their own unique setof driver errors, depending on the typeof intersection at hand.

Signalized Intersections

Common driver errors include:

� Not understanding whether toproceed or stop at a yellow-signalindication (e.g.This is known as thedilemma zone);

� Underestimating time to reach anintersection;

� Underestimating time to make asmooth stop;

� Failure to detect signal and properlane assignment; and

� Misinterpreting guide sign informa-tion.

Unsignalized Intersections

Common driver errors include:

� Unsafe gap acceptance;

� Inaccurate estimation of approach-ing vehicles’ speed;

� Underestimating time to accelerateafter making a turn; and

� Failure to yield right-of-way.

Design Considerations

Design policy implicitly incorporatesprinciples of human factors.The “designdriver” is assumed by AmericanAssociation of State HighwayTransportation Officials (AASHTO) tobe alert and in control of physical andmental abilities; to have a reasonable abil-ity to see and perceive the roadway envi-ronment; and to have reasonable motorskills to enable steering, braking andother operations. Table 2 summarizeskey human factor considerations andtheir relationship to design elements.

HUMAN FACTORS April 2004 2

EngineeringSolutionsHumans are not perfect when makingdecisions, and some errors in judgmentare inevitable. However, steps can betaken to help reduce the likelihood thatdriver errors will take place.Therefore,intersection design and features areimportant and should take the limita-tions of human performance intoaccount.

A signification proportion of intersec-tion crashes involve left-turn maneu-vers. Older drivers in particular run thegreatest risk of being involved in a left-turn accident, due in part to theirdiminished ability to judge closure ratesof oncoming vehicles. Using alternativeintersection designs for left-turn lanescan help alleviate this problem. Forexample, a positive offset design can

help improve visibility of oncomingvehicles. Adding protected left-turnphases can also assist drivers in turningmovements.

Other elements of the intersection canbe added or modified to improve driv-er performance and reduce the likeli-hood of errors. Some include:

� Using advanced guide signs thatare placed in conspicuous loca-tions;

� Using large pavement markingsand scribing path markings formultiple turn lanes;

� Using larger 12 in. signals or bea-cons;

� Using pedestrian refuge islandswhen possible;

� Reducing size of dilemma zonewith appropriate amber-phasetiming or advanced detection;

Table 2:Human Factors and Their Relationship to

Roadway Design Elements

Human Factor Design Value Design Element Affected

Perception-reaction time 1.0-2.5 sec. Stopping Sight DistanceDeceleration rate 11.2ft./sec.2 Stopping Sight DistancePre-maneuver. 3.0-9.1 sec. Decision Sight DistancesDistance for driver to detect an unexpected condition.Gap acceptance 7.5 sec. Minimum Stopping Sight DistanceTurning left or right from stop 6.5 sec. Minimum Stopping Sight DistanceCrossing from stopDriver height of eye 1080 mm Stopping Sight DistancePedestrian walk times 3.0-4.5 fps Pedestrian Facilities

� Ensuring that the intersection isfree of visual obstructions;

� Avoiding permissive right-turn-on-red when intersection skewangle is less than 75 degrees; and

� Ensuring crosswalks are easilyvisible with high visibility mark-ings and/or beacons.

TrainingNational Highway InstituteCourse:

Human Factors forTransportation Engineers

For further information, contactFHWA, Office of Safety, at 202-366-8156.

This one-day workshop includesinteractive modules on informationreception, decision-making, driverresponses and human factors princi-ples. Upon completion of the course,participants will be able to:

� Recognize that human factorshave a role in highway design,operations and safety decisions;

� Describe human factors infor-mation that is included in today'sguidelines and standards;

� Identify human capabilities need-ed for using roadways; and

� Apply basic human factors prin-ciples to resolve issues relatedto highway design, operationsand safety.

Resources1. American Association of State Highway

and Transportation Officials. A Policy onGeometric Design of Highways and Streets,Fourth Edition. Washington, DC: AASHTO,2001.

2. Institute of Transportation Engineers.Traffic Engineering Handbook, 5th Edition.Washington, DC: ITE, 1999.

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Access Management:A Key to Safety and MobilityAccess management can be defined as the process or development of a program intended to ensurethat the major arterials, intersections and freeway systems serving a community or region will oper-ate safely and efficiently while adequately meeting the access needs of the abutting land uses alongthe roadway.The use of access management techniques is designed to increase roadway capacity,manage congestion and reduce crashes.

Through the years, extensive investment for public roadway infrastructure has been made.This haslargely involved public funds, but private monies also have contributed to rebuilding and enhancingthe street system. During the past 30 years or more, the ability to increase roadway capacity hasbeen increasingly difficult due to both economic and environmental constraints.Areas that do notpractice effective access management face more rapid deterioration of the quality of traffic flow thanthose areas with a well-thought out access management policy in place.

The purpose of this briefing sheet is to describe the traffic engineering and design considerations inrelation to the use of access management techniques to increase safety and reduce crashes.

The lack of an access management plan or policy will ultimately result in a number of negative con-sequences including:

� Reduction in overall safety reflected by the increase in crashes;� Greater number of conflicts and potential hazards between vehicular bicycle and pedestrian

movements;� Diversion of through traffic into abutting neighborhoods in attempt to bypass added congestion;� Increased congestion with slower travel speeds and delays to arterial traffic; and� Non-transportation effects such as increase in strip commercial development, less pleasing visu-

al settings and ultimately, a poor image for the businesses along the corridor.

Traffic Engineering and Design Considerations to Enhance AccessManagement

Some of the most significant areas to address in relation to access management are related to traf-fic signal spacing, the number of driveways and the characteristics of an intersection.

Traffic Signal SpacingFigure 1 shows comparativeaccident rates for a givensignal density and numberof unsignalized accesspoints per mile. The graphclearly shows that a greaternumber of access pointsand signals per mile trans-late into increases in crashrates. As an example, if thenumber of access pointsare held constant at less

Access Management

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Figure 1

Access Management

than 20 unsignalized access points permile, and the number of signals per mileare categorized as less than two, ascompared to two to four signals permile, there is a 50 percent increase inthe crash rate (from 2.6 million vehiclemiles of travel (mvmt) to 3.9 mvmt.

Table 1 considers the number of signalsper mile in comparison to crash datacompiled from seven states. As shown,there is an increase in the crash rate of158 percent (from 3.53 crashes permvmt to 9.11 crashes per mvmt) whenunder conditions of less than two sig-nals per mile as compared to six ormore signals per mile.

IntersectionSpacingAs the number of intersections per mileincreases, the opportunity for crashesincrease. The existence of too manyintersections per mile also increasesdelay and congestion.Table 2 provides afew rules of thumb for intersectionspacing:

The Iowa Department of Transportationconducted an access managementresearch project and collected data inseven communities in conjunction withthe development of an access manage-ment awareness program. Figure 2shows the number and type of accidents

per year (and percentage reduction)prior to and after implementation of aseries of access management tech-niques. As shown, total accidents werereduced by approximately 39 percent;and rear-end and left-turn accidentswere reduced by 41 and 42 percent,respectively.

Functional Areasof Intersections The functional area of an intersection isthat area beyond the physical intersec-tion of two roadways that comprisesdecision and maneuvering distance, plusany required vehicle storage length.Thefunctional area includes the length ofroad upstream from an oncoming inter-section needed by motorists to per-ceive the intersection and begin maneu-vers to negotiate it.

The upstream area consists of distancefor travel during a perception-reactiontime, travel for maneuvering and decel-eration and queue storage. The func-tional area includes the length of road

downstream from the intersectionneeded to reduce conflicts betweenthrough traffic and vehicles entering andexiting a property.

Driveways located within the functionalarea may create too many conflictpoints within too small an area formotorists to safety negotiate.

The integrity of functional areas ofintersections can be protected throughcorner clearance, driveway spacing andintersection spacing requirements.Intersections should be spaced farenough apart so that functional areasdo not overlap.

ACCESS MANAGEMENT April 2004 2

Table 1

Signal Per Mile Crashes Per MVMT

Under 2 3.532 to 4 6.894 to 6 7.49

6+ 9.11

Table 2

Intersection Spacing/ SuggestedRoadway Types Spacing

Arterial (major roadway) to arterial (intersecting minor ≥ 1 mileroadway)Arterial (major roadway) to collector (intersecting minor ≥ 0.5 mileroadway)Intersection of local roads with arterials is not 500 to 660 feetrecommended; However if requiredRural areas, intersections 0.5 mile;between public roads preferred 1 mile

Figure 2

Driveways should not belocated within the

functional area of anintersection.

Figure 3

AccessManagementTools andTechniquesThere are a number of other toolsand techniques available to considerfor use as part of an access manage-ment plan.They include both physicaldesign techniques as well as policyrelated addressing land developmentand roadway design standards.Examples of common and highlyeffective techniques are:

� Consolidate and minimize leftturn exits from driveways;

� Use a two-way center left-turnlane;

� Use of raised center median;� Encourage shared driveways for

adjacent land parcels/develop-ments;

� Create service roads for directland access parallel to majorarterial; and

� Provision of adequately designedturn lanes.

Resources1. American Association of State Highway

Transportation Officials. A Policy onGeometric Design of Highways and Streets.Washington, DC:AASHTO, 2001.

2. Center for Transportation Research andEducation. Intersection Spacing and TrafficSignal Spacing, Access ManagementFrequently Asked Questions 4;http://www.ctre.iastate.edu/Research/access/toolkit/4.pdf

3. Center for Transportation Research andEducation. Intersection Spacing and TrafficSignal Spacing, Access ManagementFrequently Asked Questions 5;http://www.ctre.iastate.edu/Research/access/ toolkit/5.pdf

4. Center for Transportation Research andEducation. Intersection Spacing and TrafficSignal Spacing, Access ManagementFrequently Asked Questions 13;http://www.ctre.iastate.edu/research/access/ toolkit/13.pdf



7. FHWA. Benefits of Access Management,FHWA Document FHWA-OP-03-066.

8. Institute of Transportation Engineers. TheTraffic Safety Tool Box: A Primer on TrafficSafety.Washington, DC: ITE, 1993.

9. Iowa Department of Transportation andthe Iowa Highway Research Board. AccessManagement Awareness Program, Phase IIReport, the Iowa DOT Project TR-402CTRE Management Project 97-1. Centerfor Transportation Research and EducationCTRE, December 1997.

10. Parsonson, P.S. M.Walters, and J. S. Fincher.Effect on Safety of Replacing an ArterialContinuous Two-Way Left-Turn Lane with aRaised Median. 1st National Conference onAccess Management.Vail, CO, 1993.

11. Parsonson, P.S. M.Walters, and J. S. Fincher.Georgia Study Confirms the Continuing SafetyAdvantage of Raised Medians over ContinuousTwo-Way Left-Turn Lanes. 4th NationalConference on Access Management.Portland, OR, 2000.

12. S & K Transportation Consultants. Inc.Access Management, Location and Design,Participant Notebook for NHI Course133078. National Highway Institute, April2000.

13. Transportation Research Board. AccessManagement Manual.

14. Transportation Research Board. NCHRP348, Access Management Guidelines forActivity Centers.Washington, DC:TRB, 1992.

15. Transportation Research Board. NCHRP420, Impacts of Access ManagementTechniques.Washington, DC:TRB, 1999.

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History of RoundaboutsThe “modern roundabout” is commonly confused with older-style traffic circles and rotaries.Traffic circles have been around almost a century, with the first documented one being built in1905 on the southwest corner of Central Park in New York City and named after ChristopherColumbus. From the start, traffic circles provided the ability for a city to tie a number of inter-secting streets together and make a landscaped central circle that had aesthetic value to the com-munity. Many large circles or rotaries were built in the United States until the 1950s when theyfell out of favor.The older-style rotaries enabled high-speed merging and weaving of vehicles thatled to a high crash experience.

The modern roundabout was developed in the United Kingdom to rectify problems associatedwith these traffic circles. In 1966, the United Kingdom adopted a mandatory “give-way” rule at allcircular intersections, which required entering traffic to give way, or yield, to circulating traffic.Thisrule prevented circular intersections from locking up by not allowing vehicles to enter the inter-section until there were sufficient gaps in circulating traffic.

What is a Modern Roundabout? A modern roundabout is a one-way circular intersection without traffic signals in which trafficflows around a center island. Roundabouts feature yield control for all entering traffic, channelizedapproaches and appropriate geometric curvature to ensure that travel speeds on the circulatoryroadway are typically less than 30 mph. Roundabouts must be designed to meet the needs of allusers—drivers, pedestrians, pedestrians with disabilities and bicyclists. When designing round-abouts, special considerations must be given to the needs of pedestrians with visual disabilitieswho are unable to judge adequate gaps in traffic at roundabouts. Proper site selection and pedes-trian channelization are essential to making roundabouts accessible to all users. Roundabouts canalso be designed for trucks and larger vehicles and in geographic areas where significant snowfallis the norm during the winter.

RoundaboutsA proven safety solution that reduces the number andseverity of intersection crashes.

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Roundabouts

Features of ModernRoundaboutsThe design and traffic control featuresof roundabouts are as follows:

� Yield control is used on all entries.

� The circulatory roadway has notraffic control. Circulating vehicleshave the right-of-way. All vehiclescirculate counter-clockwise andpass to the right of the centralisland.

� Central island. Once within thecirculatory roadway, vehicles’paths are further deflected by thecentral island.

� Pedestrian access is allowed onlyacross the legs of the roundabout,behind the yield line to the circula-tory roadway. Pedestrian crossingsare located at least one vehiclelength upstream of the yield point.

� Splitter island.A splitter island isa raised or painted area on anapproach used to separate enter-ing from exiting traffic, deflect andslow entering traffic and providestorage space for pedestrianscrossing the road in two stages.

� Yield line is a pavement markingused to mark the point of entryfrom an approach into the circula-tory roadway. This is generallymarked along the inscribed circle.Entering vehicles must yield to anycirculating traffic coming from theleft before crossing this line intothe circulatory roadway.

� Landscaping buffer Landscapingbuffers are provided at mostroundabouts to separate vehicularand pedestrian traffic and toencourage pedestrians to crossonly at the designated crossinglocations. Landscaping buffers canalso significantly improve the aes-thetics of the intersection.

� Accessible pedestrian cross-ings. Accessible pedestrian cross-ings should be provided at allroundabouts.The crossing locationis set back from the yield line andthe splitter island is cut to allowpedestrians, wheelchairs, strollersand bicycles to pass through.

Tactile surfaces should be used towarn pedestrians with visual dis-abilities that they are about toenter the roadway.

RoundaboutSafetyResearch indicates that well-designedroundabouts can be safer and more effi-cient than conventional intersections.Safety benefits of roundabouts include:

� Roundabouts have fewer conflictpoints in comparison to conven-tional intersections. The potentialfor hazardous conflicts, such asright-angle and left-turn head-oncrashes is eliminated with round-about use. Single-lane approachroundabouts produce greater safe-ty benefits than multilaneapproaches because of fewerpotential conflicts between roadusers and because pedestriancrossing distances are shorter;

� Low absolute speeds associatedwith roundabouts allow driversmore time to react to potentialconflicts, also helping to improvethe safety performance of round-abouts;

� Since most road users travel atsimilar speeds through round-abouts, i.e., have low relativespeeds, crash severity can bereduced compared to some tradi-tionally controlled intersections;

� Roundabouts have fewer annualinjury crashes than rural two-waystop-controlled intersections, andthe total number of crashes atroundabouts is relatively insensi-tive to minor street demand vol-umes; and

� Roundabouts have fewer injuryaccidents per year than signalizedintersections, particularly in ruralareas. At volumes greater than50,000 average daily traffic (ADT),urban roundabout safety may becomparable to that of urban sig-nalized intersections.

Table 1 shows the crash frequencies(average annual crashes per round-about) experienced at 11 intersectionsin the United States that were convert-ed to roundabouts. As the exhibitshows, both types of roundaboutsshowed a reduction in both injury andproperty-damage crashes after installa-tion of a roundabout.

A December 2002 report by theMaryland Highway Administration indi-cates that 15 single-lane roundaboutshave greatly improved intersection safe-ty in the state. The analysis shows thatthere has been a 100 percent decreasein the fatal crash rate; a 60 percentdecrease in the total crash rate; an 82percent reduction in the injury crashrate; and a 27 percent reduction in theproperty damage only accident rate.

ROUNDABOUTS April 2004 2

Table 1

Before Roundabout Roundabout Percent Change 5

Type of Roundabout Sites Total Inj.3 PDO4 Total Inj. PDO Total Inj. PDO

Small/Moderate1 8 4.8 2.0 2.4 2.4 0.5 1.6 -51% 73% -32%

Large2 3 21.5 5.8 15.7 15.3 4.0 11.3 -29% 31% -10%

Total 11 9.3 3.0 6.0 5.9 1.5 4.2 -37% 51% -29%

Notes:1. Mostly single-lane roundabouts with inscribed circle diameter of 100 ft. to 115 ft.2. Multilane roundabouts with an inscribed circle diameter greater than 165 ft.3. Inj. = Injury crashes4. PDO = Property Damage Only crashes5. Only injury crash reductions for small/moderate roundabouts were statistically significant.

Source: Jacquemart, G. Synthesis of Highway Practice 264: Modern Roundabout Practice in theUnited States. National Cooperative Highway Research Program. Washington, DC: NationalAcademy Press, 1998.

Roundabouts

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Safety ProblemsSusceptible toCorrection byRoundaboutsThe decision to install a roundaboutas a safety improvement should bebased on a demonstrated safetyproblem of the type susceptible tocorrection by a roundabout.A reviewof crash reports and the type of acci-dents occurring is essential.

Examples of safety problems include:� High rates of crashes involving

conflicts that would tend to beresolved by a roundabout (right-angle, head-on, left/through, U-turns, etc.);

� High-crash severity that could bereduced by the slower speedsassociated with roundabouts;

� Site visibility problems thatreduce the effectiveness ofSTOP sign control (in this case,landscaping of the roundaboutneeds to be carefully consid-ered); and

� Inadequate separation of move-ments, especially on single-laneapproaches.

Issues to Review WhenConsidering RoundaboutDesign Alternatives

During the planning and alternativesdevelopment stage of a project, thefollowing issues should be consideredprior to making the decision toimplement a roundabout design:

� Context. What are the region-al policy constraints that mustbe addressed? Are there site-specific and community impactreasons why a roundabout ofany particular size would not bea good choice?

� Space feasibility. Is thereenough right-of-way to build theroundabout? Is right-of-wayacquisition required? If “yes,”this introduces administrativecomplications that some agen-cies might want to avoid.

� Physical or geometric com-plications such as right-of-waylimitations, utility conflicts, drain-age problems and unfavorabletopography that may limit visibilityor complicate construction.

� Proximity of generators ofsignificant traffic that might havedifficulty negotiating the round-about, such as high volumes ofoversized trucks.

� Proximity of traffic controldevices that would require pre-emption, such as railroad tracksor drawbridges.

� Traffic congestion that wouldcause routine back-ups into theroundabout, such as over-capac-ity signals or freeway entranceramps. The successful operationof a roundabout depends onunimpeded flow on the circula-tory roadway.

� Intersections of a majorarterial and a minor arterialor local road where an unac-

ceptable delay to the major roadcould be created. Roundaboutsdelay and deflect all traffic enter-ing the intersection and couldintroduce excessive delay orspeed inconsistencies to flow onthe major arterial.

� Heavy pedestrian or bicyclemovements in conflict withhigh traffic volumes. (These con-flicts pose a problem for alltypes of traffic control.)

� Coordinated signal system.Intersections located on arterialstreets within a coordinated sig-nal network. In these situations,the level of service on the arte-rial might be better with a sig-nalized intersection incorporat-ed into the system.

The existence of one or more ofthese conditions does not necessarilypreclude the installation of a round-about. Roundabouts have, in fact, beenbuilt at locations that exhibit nearlyall of the conditions listed above.Theymay be resolved through coordina-tion with and support from otheragencies and implementation of spe-cific mitigation actions.

Resources 1. FHWA has published a comprehensive

guide called Roundabouts: An InformationalGuide.The information supplied in this doc-ument is based on established internation-al and U.S. practices and is supplementedby recent research. Call 202-366-5915 toorder Publication No. FHWA-RD-00-067,or download this guide from the Internetat http://www.tfhrc.gov/safety/00068.htm

2. Florida Department of Transportation.Florida Roundabout Guide. FloridaDepartment of Transportation, March1996.

3. Garder, P. The Modern Roundabouts: TheSensible Alternative for Maine. MaineDepartment of Transportation, Bureau ofPlanning, Research and CommunityServices,Transportation Research Division,1998.

4. Jacquemart, G. Synthesis of HighwayPractice 264: Modern Roundabout Practice inthe United States. National CooperativeHighway Research Program. Washington,DC: National Academy Press, 1998.

What is a Road Safety Audit?Every year, a large number of people are killed and injured on roads in developed and developingcountries. Every year, states, counties, regions and municipalities spend considerable amount ofresources on trying to reduce crashes by reconstructing and improving the roads. This work—crash reduction—is still necessary and should continue to be of high priority. However, theseactivities are reactive.

New roads must incorporate design and operational safety elements from the start. Roadway safe-ty in new projects can be improved by having independent road safety specialists systematicallyexamining and commenting on the projects, while they still only exist on paper. This is called aroad safety audit (RSA).

RSAs are in essence, crash prevention.The purpose is to make new roads as safe as possible—before the projects are implemented, and before any crashes happen. RSAs require an independ-ent and systematic formal procedure for assessing or checking the crash potential and safety per-formance of a new road project or existing roads. Safety should be considered throughout theentire project—from planning and development, to construction and operations and maintenance.

The basis for a RSA is the application of safety principles to new project design and improvementsto the highway to prevent crashes from occurring or to reduce their severity.The outcome of theaudit is the identification of any potential safety issues, together with suggestions on how toaddress the issues.Additionally, road safety audits are systematic; auditing takes place according toagreed upon procedures, in which the parties involved have designated roles in the process.

The central principle of an RSA is the independence of the auditors.The auditors exclusively eval-uate the road safety of projects—and not participants in the planning or design of the projectitself. Furthermore, it is not the task of the auditors to weigh safety considerations against otherconsiderations, e.g., economic criteria although they may be aware of them.

Road safety audits can be applied to both smallas well as large projects, regardless of whetherthe project concerns new construction or therebuilding of existing roads.

It will often be advantageous to carry out anaudit several times during the course of a proj-ect, depending on its size, complexity and char-acter. Therefore, the following five stages havebeen defined:

� Stage 1: Planning � Stage 2: Preliminary Design � Stage 3: Detailed Design � Stage 4: Construction � Stage 5: Monitoring Existing Projects

Road Safety Audits: AnEmerging and EffectiveTool for Improved Safety

1ROAD SAFETY AUDITS April 2004

"We view RSAs as a proactive low-costapproach to improve safety.

The RSAs helped our engineeringteam develop a number of solutions

incorporating measures that were notoriginally included in the projects.

The very first audit conducted savedSCDOT thousands of dollars by correcting a design problem.”

Terecia Wilson,Director of Safety

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Road Safety Audits: An Emerging and Effective Tool for Improved Safety

It is essential that the suggestions of theRSA are consistent with the stage ofthe project. For example, audit sugges-tions related to design details are inap-propriate at the planning phase, andaudit suggestions that require majordesign alterations are inappropriate atthe detailed design phase. Experiencedauditors will limit the safety audit sug-gestions to items that can still be prac-tically and cost-effectively addressed atthe stage of the project.

The final design-related decisions arealways the responsibility of the designteam and the project owner. The audi-tors simply provide input, and thedesign team and owner have absoluteflexibility to accept or reject any of theaudit suggestions, with proper justifica-tion and documentation.

Who needs RSAguidelines?RSAs should be an integral part of high-way planning, design, construction andmaintenance.Therefore, there needs tobe an explicit commitment to safetyamongst elected officials, managementin any transportation organization,together with an awareness of the roleand benefits of safety audits.

The RSA process requires an objectiveapproach to the assessment of crashrisk. The principal method of ensuringthis objectivity is through the inde-pendent safety assessment of projectsby persons not connected with theoriginal design. Designers and plannersneed to be familiar with procedures andpractices, and provide the necessarybackground information required forthe audit to be undertaken.A designat-ed audit team should undertake theaudit with experience conducting roadsafety engineering techniques.

What Should beAudited?Projects eligible for audit cover a widerange of types and sizes, on differentclasses of roads, in urban and ruralareas. The variety of design is broadlycovered under the following categories:

(i) major highway projects; (ii) minorimprovements (rehabilitation, retro-fitting, upgrading) projects; (iii) trafficmanagement plans; (iv) developmentprojects; and (v) maintenance.

Ideally, all projects should be subject toan independent safety audit. If this is notachievable within available resources, aclear procedure is required for priori-tizing projects in terms of type of proj-ect and level of audit required. Projectsthat benefit from audits typically havethe following characteristics:

� Complex, unusual, or new designcharacteristics;

� Significant budget or land con-straints;

� A high public profile; and� A history of high crash risk at the

project location.

What resourcesare needed?RSAs require the assembly of a RSAteam, and some resources from the

design team and the owner to compileinformation, attend meetings andrespond to the audit suggestions.

The cost of a road safety audit is oftenan insignificant amount compared tothe overall project cost. In the UnitedStates and Canada, highly complex RSAsfor major projects (with a capital cost inthe hundreds of millions of dollars) havebeen conducted at a cost of $30,000 to$40,000. Small audits for relativelyminor projects can be completed for acost of $15,000 or less. Audits can beconducted by in-house transportationdepartment staff or from a consultingorganization.

The cost of implementing the accept-able suggestions from the RSA (includ-ing re-design) may be relatively low andmanageable, since by definition RSAsuggestions need to be compatible andcost-efficient relative to the phase ofthe project. Allowance should be madein the original design costing and timeschedule of projects for both audit andpossible redesign.

ROAD SAFETY AUDITS April 2004 2

Before RSA

After RSA

What are theBenefits ofRSAs?It is difficult to quantify the benefits ofroad safety audits, since by definitionaudits are preventing crashes fromoccurring. Studies that have attempt-ed to quantify the benefits of auditshave yielded impressive results. In theUnited Kingdom, a local authority hasestimated the benefit-cost ratio of anRSA to be 15:1, while TRANSIT NewZealand has estimated the benefit tocost ratio as 20:1. Cost-benefit analy-sis of safety audited projects inDenmark yielded an expected aver-age first year rate of return of 146percent.

With the low cost of conducting roadsafety audits, it is fair to say thataudits need only to prevent a verylow number of crashes, injuries andfatalities over the life of the project toprovide a high benefit to cost ratio.

Who is NowUsing orPlanning to UseRoad SafetyAudits? The RSA concept was originallydeveloped and introduced in theUnited Kingdom (UK) in 1989. Thebenefits of such systematic checkingwere soon recognized by many safetyprofessionals around the world andthe following countries, among manyothers, are actively conducting RSAs:USA, Canada, UK, Australia, NewZealand, Denmark, Norway, Ireland,Singapore, India, Italy and Malaysia.

Road SafetyAudits in theUnited Statesand CanadaThere are many successful on-goingRSA programs in the United Statesand Canada. The states ofPennsylvania, Iowa, New York,Minnesota and South Carolina areactively conducting RSAs. The firstRSA for a mega-project was conduct-ed in 2003 at the MarquetteInterchange in Milwaukee,Wisconsin.In Canada, the provinces of BritishColumbia, Alberta and NewBrunswick have been actively imple-menting RSAs. In 2001, a NationalRoad Safety Audit Guide was publishedby the Transportation Association ofCanada (TAC). RSA training is avail-able in both countries, through theNational Highway Institute (NHI) inthe United States and through TAC inCanada.

Road Safety Audit Training

National Highway Institute (NHI)Course 380069ARoad Safety Audit and Road SafetyAudit Reviewshttp://www.nhi.fhwa.dot.gov703-235-0528

Transportation Association ofCanada (TAC}http://www.tac-atc.ca/english/educationandtraining/courses-safetyaudit.cfm613-736-1350 ext. 261

Key References1. Transportation Association of Canada.

Canadian Guide to Road Safety Audits.Ottawa:TAC, 2001.

2. Institution of Highways and Transportation.Guidelines for the Safety Audit of Highways,London: IHT, London, 1996.

3. Ministry of Transport. Manual of SafetyAudit, Road Directorate. Copenhagen,Denmark: 1997.

4. Transfund New Zealand. Safety AuditProcedures for Existing Roads. Wellington:TNZ, 1998.

5. Asian Development Bank. Road Safety Auditfor Road Projects – An Operational Toolkit.Manila:ADB, 2003.

6. Public Works Department. Guidelines forthe Safety Audit of Roads and Road Projects inMalaysia. Kuala Lumpur: PWD, 1997.

7. Transportation Research Board. RoadwaySafety Tools for Local Agencies, NCHRPSynthesis Report 321. Washington, DC:TRB, 2003.

8. A. Schelling. Road Safety Audit—The DanishExperience. (Presentation at IRSAF inLondon) Road Directorate, Copenhagen:2003.

9. P. Jordan. The Costs and Benefits of RoadSafety Audit. (Presentation at IRSAF inLondon), Melbourne:Vic Roads, 2003.

10. I. Appleton. The Safety Audit of ExistingRoads. (Presentation at PIARC C13 meet-ing in Lisbon),Wellington:TNZ, 2003.

11. E. Wilson. Auditing of Existing Routes –Experiences from the USA, Presentation atIRSAF. Wyoming: 2003.

Road Safety Audits: An Emerging and Effective Tool for Improved Safety

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It is a challenge to maintain safety and mobility at intersections in a work zone. For drivers unfa-miliar with an intersection, a work zone can be a sudden, potentially dangerous surprise. Formotorists who regularly drive through an intersection, a work zone can be a frustrating nuisancebecause of the way it adds to travel time. But the development and application of well-designedtemporary traffic control plans can ensure safe mobility for workers and all road users (motorist,bicyclists and pedestrians including persons with disabilities) in an intersection work zone.

OverviewWork zones at intersections present variousengineering design challenges. Intersectioncrashes represent about 16 percent of thetotal work zone fatalities in the last 5 years.The task of maintaining mobility and ensuringsafety for pedestrians, bicyclists, workers,motorists and transit operations is moredemanding at intersections than on road seg-ments. The realignment of travel lanes andreduction of road capacity are often necessaryto accomplish reconstruction or rehabilita-tion, such as pavement replacement, pavementpatching, widening a street, utility work andreapplying pavement markings.All of these cancause delays and pose a threat to safety.

Transportation agency coordination with transit, police, fire, emergency medical services, utilities,schools and railroads should occur (especially in urban areas) to alert these organizations tochanges in road conditions. Suggesting alternate routes is time well spent to ensure safety andtravel time reliability, particularly for school buses and emergency providers.

MUTCD, Part 6, Temporary Traffic ControlThe Manual on Uniform Traffic Control Devices (MUTCD) contains the basic principles of design anduse of traffic control devices for all streets and highways open to public travel, regardless of typeor class, or the public agency having jurisdiction.The latest version of the MUTCD, Part 6 titled“Temporary Traffic Control” was published November 20, 2003 and contains the standards, guid-ance, options and support information related to work zones. Part 6 has been significantly revisedand expanded with new signs and revised "Typical Applications" detailed for a variety of street andhighway work situations commonly encountered by road users.There is new language about theheight and projection of signs in accordance with the American with Disabilities Act.There is alsoguidance for providing detectable paths for protecting pedestrians with visual disabilities in urbanareas.The MUTCD can be accessed at the following Web site: http://mutcd.fhwa.dot.gov.

Cones or drums knocked out of alignment by an errant driver or a work vehicle, for example,could result in vehicles being channeled into oncoming traffic.The condition of devices should alsobe checked regularly to ensure that they continue to perform as intended. Modifications may alsobe necessary based on changing road conditions or work staging and progress. Safety in a tempo-rary traffic control zone is the responsibility of the contractor, transportation agency and the driv-er. No traffic control device, however, can overcome the shortcomings of imprudent drivers.

Work Zone Intersection Safety

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Work ZoneIntersectionSafety GoalsMotorists entering and travelingthrough work zones must be providedwith adequate time and distance tomake decisions and stop whenrequired. Drivers should never beforced to make unexpected stops orperform unanticipated steering orcrash-evasion maneuvers whenapproaching or within a work zone.

Traffic congestion in intersections shouldbe mitigated to the greatest extent pos-sible. If long queues are expected or areoccurring because of a work zone, addi-tional advance traffic control devicesmay be necessary to provide users withinformation about lane choice or alter-nate routes before being trapped in aqueue. Long delays often create impa-tient drivers who may change their usu-ally good driving habits and take unnec-essary risks that result in potential haz-ards to themselves and others.Pedestrians and bicyclists may ignoresigns and walk against traffic signals ifthey are forced to wait too long to beaccommodated in a work zone. Thisincreases their vulnerability to vehicleswhose drivers may also be frustrated.

Improving WorkZone IntersectionSafetyEnsuring a high level of intersection workzone safety depends on proper pedestri-an accommodation, worker safety andvisibility and proper traffic control.

Pedestrian AccommodationsIn Work Zones

� Access to temporary transit stopsshould be provided;

� Temporary crosswalk facilitiesshall be detectable;

� Curb parking shall be prohibitedwithin 15 m (50 ft.) of the mid-block crosswalk;

� Pedestrian signals should be deac-tivated for closed crosswalks;

� Nighttime lighting may be consid-ered; and

� Alternate route informationshould be communicated topedestrians with visual disabilitiesby providing such things as audibledevices, accessible pedestrian sig-nals, or barriers and channelizingdevices that are detectable.

Did you consider:

� Special consideration for seniorsand pedestrians with disabilities(lower walking speeds at signalizedintersections, refuge island at wideintersections, flared curbs, over-sized signs and signals, night light-ing)?

� Adequate pedestrian protection –physical separation from the work-space and vehicular traffic, over-head protection, etc.?

� Requirements of the Americanwith Disabilities Act (ADA) of1990?

� Location/access to business andresidences?

� Adequate and safe detour ordiversion due to sidewalk closureor blockage?

� Impact on existing pedestrianflow?

� Impact on pedestrian generators(schools, senior centers and tran-sit stops)?

� Pedestrian information needs—advance, transition, work area andexit information?

Worker Safety atIntersections Worker safety in work zones, especiallyat intersections, is an overarching con-sideration for highway agencies and util-ity companies.The combination of heav-ier traffic and a greater reliance on nightwork results in increased risks for high-way workers. As a rule of thumb, flag-gers or highway workers should notcontrol intersections controlled by traf-

WORK ZONE April 2004 2

Note: For long-term stationary work, the double yellow centerline and/or lane lines should be removed between the crosswalk lines.

See Tables 6H-2 and 6H-3 for the meaning of the symbols and/or letter codes used in this figure.(optional)

Temporarymarking for crosswalk lines(cross-hatchingoptional)

(optional)

fic signals or STOP signs. Police offi-cers generally receive training for thisjob. Other methods that can be usedto minimize and control risks forworkers are as follows:

� High-visibility apparelAll workers exposed to trafficshould wear high-visibility safetyapparel labeled as ANSI 107-1999and be classified as either Class 1,2, or 3 for risk exposure;

� Worker TrainingAll workers should be trained onhow to work next to motor vehi-cle traffic in a way that minimizestheir vulnerability;

� Positive SeparationTemporary traffic barriers shouldbe placed along the work spaceon various factors such as dis-tance between workers and traf-fic, traffic speed and volume, timeof day and duration and type ofoperation;

� Worker Safety PlanningPlanning, implementation andoversight of worker safety shouldbe the responsibility of a compe-tent safety specialist, and shouldadequately address the require-ments of OSHA and theMUTCD;

� Activity Area PlanningPlanning the internal work activi-ty area to minimize backing-upmaneuvers of construction vehi-cles should be considered to min-imize exposure to risk; and

� Speed ControlCompliance with posted speedlimits, mainly through regulatoryspeed zoning, funneling, lanereduction, or the use of uni-formed law enforcement offi-cers or flaggers, should be con-sidered.

ImprovingTemporaryTraffic Controlat IntersectionsWhen the normal function of theintersection is suspended due toroadwork, temporary traffic controlplanning provides for the continuityof movement of motor vehicle; bicy-cles; pedestrian traffic (includingaccessible passage); transit opera-tions; and access (and accessibility) toutilities. Nighttime roadwork alsocontinues to increase and the safetyissues relating to traffic control are amajor concern.

The following strategies can improvetraffic safety and mobility in workzones:

� Enhanced Traffic ControlDevicesWhere possible use drums, ver-tical panels, or Type II barricadesin tapers instead of cones.Thesedevices provide more targetarea than cones;

� Visibility of Work VehiclesHigh visibility of work vehicles atintersections, especially at nightmay reduce the risk of crashes;

� Controlling Speed andIncreasing DriverAwarenessAlthough designing work zonesto maintain normal speeds isdesirable, restrictions may benecessitated by such things aslane width reductions, severealignment changes, or workersexposed to high-speed traffic;

� Providing Good, Glare-FreeIlluminationFor night work at intersectionsproperly aimed and adjustedwork lights can provide goodillumination without causingglare problems; and

� Regularly check the worksite to ensure that theplacement and operation oftraffic control devices con-tinue to conform to applica-ble plans.

ResourcesThe FHWA developed the BestPractices Guidebook for Work ZoneSafety to give state and local trans-portation agencies, construction con-tractors, transportation planners,trainers and others with interest inwork zone operations, access to con-tacts and information about currentbest practices for achieving workzone mobility and safety. More infor-mation on this guidebook can beobtained on the following Web site:h t t p : / / o p s . f h w a . d o t . g o v / w z /wzguidbk/.


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AAdvocates for Highway and Auto Safety. Driving the Agenda: Intersection Safety—Potential Federal FundingSources for Safety Improvements. April 2001. http://www.saferoads.org/polls/intersectionsafety2001.htm

Agent, Kenneth R. et. al. Development of Accident Reduction Factors. Research Report KTC-96-13. KentuckyTransportation Center College of Engineering, June 1996. http://www.ktc.uky.edu/Reports/KTC_96_13.pdf

American Association of State Highway and Transportation Officials.� Highway Safety Design and Operations Guide.Washington, DC:AASHTO, 1997.� Policy on the Geometric Design of Highways and Streets.Washington, DC:AASHTO, 2001.

EEhlinger, P.E., Erin. Successful Traffic Signal System Procurement Techniques, A Summary of Effective Processes,FHWA-OP-02-032. January 31, 2002. http://www.itsdocs.fhwa.dot.gov/jpodocs/repts_te/13611.html

FFederal Highway Administration.

� Accident Models for Two-Lane Rural Roads: Segments and Intersections, FHWA-RD-98-133.October 1998.http://www.tfhrc.gov/safety/98133/index.html

� Automated Enforcement of Traffic Signals: A Literature Review � Association of Selected Intersection Factors with Red-Light Running Crashes, FHWA-RD-00-112.

http://www.hsrc.unc.edu/hsis/pdf/00-112.pdf� Crash Models for Rural Intersections: Four-Lane by Two-Lane Stop-Controlled and Two-Lane by Two-Lane

Signalized, Report FHWA-RD-99-128. 1999.http://www.fhwa.dot.gov/tfhrc/safety/pubs/99128/intro.htm

� Designing Sidewalks and Trails for Access: Best Practices Guide, Part II of II.http://www.fhwa.dot.gov/environment/sidewalk2/index.htm

� Flexibility in Highway Design. Chapter 8, Intersections, Report FHWA-PD-97-062. 1997.http://www.fhwa.dot.gov/environment/flex/ch08.htm

� Guidance for Using Red Light Cameras. FHWA-SA-03-018. March 2003.http://www.nhtsa.dot.gov/people/injury/enforce/guidance03/Guidancereport.pdf

� Guidelines and Recommendations to Accommodate Older Drivers and Pedestrians, FHWA-RD-01-051.http://www.tfhrc.gov/humanfac/01105/01-051.pdf

� Intersection Collision Warning System, FHWA-RD-99-103.http://www.fhwa.dot.gov/tfhrc/safety/pubs/its/ruralitsandr&d/tb-intercollision.pdf

� Manual on Uniform Traffic Control Devices. 2003. http://mutcd.fhwa.dot.gov/� Modeling Intersection Crash Counts and Traffic Volumes, FHWA-RD-98-096.� Prediction of the Expected Safety Performance of Rural Two-Lane Highways, FHWA-RD-99-207.� Roundabouts: An Informational Guide, FHWA-RD-00-067. http://www.tfhrc.gov/safety/00068.pdf� Statistical Models of At-Grade Intersection Accidents—Addendum, FHWA-RD-99-094.

http://www.tfhrc.gov/safety/99-094.pdf � Synthesis and Evaluation of Red-Light Running Automated Enforcement Programs in the United States,

FHWA-IF-00-004. September 1999. http://safety.fhwa.dot.gov/fourthlevel/pdf/rlrfinal.pdf� Traffic Control Systems Handbook, FHWA-SA-95-032. 1995.� Work Zone Operations Best Practices Guidebook, FHWA-OP-00-010,April 2000.

GGluck, J., H.S. Levinson and V. Stover. Impacts of Access Management Techniques, NCHRP Report420.Washington, DC:Transportation Research Board, 1999.

Griffin, Lindsay F. III. Older Driver Involvement in Injury Crashes in Texas: 1995-1999. AAA Foundation for TrafficSafety, February 2004.http://www.aaafoundation.org.pdf/OlderDriverInvolvement InInjuryCrashes.pdf

Intersection SafetyResources

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Intersection Safety Resources

HHarwood, D.W., J.M. Mason and R.E. Brydia. Intersection SightDistance, NCHRP Report 383. Washington, DC: TransportationResearch Board, 1996.

IIHSDM Intersection Diagnostic Review Model Knowledge BaseReport, FHWA-RD-02-045. March 2003.http://www.tfhrc.gov/safety/ihsdm/pubs/02045/index.htm

Institute of Transportation Engineers.� Automated Enforcement in Transportation.Washington, DC:

ITE, 1999.� Design and Safety of Pedestrian Facilities. Washington, DC:

ITE, 1998.� Engineering Countermeasures to Reduce Red-Light Running.

Washington, DC: ITE, 2003.http://safety.fhwa.dot.gov/rlr/rlrreport/RLRbook.pdf

� A History of the Yellow and All-Red Intervals for Traffic Signals.Washington, DC: ITE, 2001.

� Manual of Traffic Signal Design, 2nd Edition. Washington,DC: ITE/Prentice Hall, 1991.

� Traffic Control Device Handbook. Washington, DC: ITE, 2001.� Traffic Engineering Handbook, 5th Edition.Washington, DC:

ITE, 1999.� Traffic Safety Toolbox: A Primer on Traffic Safety.Washington,

DC: ITE, 1999.

MManual on Uniform Traffic Control Devices (MUTCD).Web site: http://mutcd.fhwa.dot.gov

NNational Highway Traffic Safety Administration.Traffic Safety Facts2002. 2002.

NCHRP� Accessible Pedestrian Signals: Synthesis and Guide to Best

Practices, Final Report, NCHRP 3-62, May 2003.http://www.walkinginfo.org/aps/pdf/APS-Synthesis.pdf

� Application of Traffic Conflict Analysis at Intersections, NCHRPReport 219.

� Evaluating Intersection Improvements: An Engineering StudyGuide, NCHRP Report 457.

� Guidance for Implementation of the AASHTO StrategicHighway Safety Plan, NCHRP Report 500.http://safety.transportation.org/guides.aspx?cid=26(HTML Version) or http://gulliver.trb.org/publications/nchrp/nchrp_rpt_500v5. pdf (PDF Version)

� Volume 5: A Guide for Addressing UnsignalizedIntersection Collisions

� Guidelines for Converting STOP to YIELD Control atIntersections, NCHRP Report 320.

� Impact of Red Light Camera Enforcement on CrashExperience. 2003http://gulliver.trb.org/publications/nchrp/nchrp_syn_310.pdf

� Integrated Management Process to Reduce Highway Injuriesand Fatalities Statewide, NCHRP Report 501.http://gulliver.trb.org/publications/nchrp/nchrp_rpt_501.pdf

� Left-Turn Treatments at Intersections, NCHRP Report 225.� Median Intersection Design, NCHRP Report 375.

� Photographic Enforcement of Traffic Laws, NCHRP Synthesis219.

� Traffic Signal Operations Near Highway-Rail Grade Crossings,NCHRP Synthesis 271.

� Single Point Urban Interchange Design and OperationsAnalysis, NCHRP Report 345.

Neumann, T. R. Intersection Channelization Design Guide, NCHRPReport 279.Washington, DC:TRB, 1985.

North Carolina Department of Transportation.� Accident Reduction Factors, Signalized Angle Crashes.

http://www.doh.dot.state.nc.us/preconstruct/traffic/safe-ty/project_ guide/arf_sig_angle.html

� Pedestrian Vehicle Crashes At Signalized Intersections.http://www.doh.dot.state.nc.us/preconstruct/traffic/safe-ty/project_ guide/arf_sig_ped.html

� Roadway Design Manual.http://www.doh.dot.state.nc.us/preconstruct/highway/dsn_srvc/value/manuals/RDM2001/part1/chapter9/pt1ch9.pdf

RRobertson, H.D., J.E. Hummer and D.C. Nelson, Manual ofTransportation Engineering Studies.Washington, DC: ITE, 1994.

SSan Diego Street Design Manual.http://www.sandiego.gov/planning/pdf/lighting.pdf

SEMCOG. Traffic Safety Manual, Second Edition. September 1997.http://www.semcog.org/TranPlan/TrafficSafety/assets/Safety_Manual.pdf

TTexas Department of Transportation.

� Bonneson, James, Karl Zimmerman and Marcus Brewer.Engineering Countermeasures to Reduce Red-Light Running,Report 4027-2. http://tcd.tamu.edu/Documents/4027-2.pdf

� Bonneson, James, Dan Middleton, Karl Zimmerman,Hassan Charara and Montasir Abbas. Intelligent Detection-Control System for Rural Signalized Intersections, Report4022-2. http://tcd.tamu.edu/Documents/4022-2.pdf

Texas Transportation Institute.� Review and Evaluation of Enforcement Issues and Safety

Statistics Related to Red Light Running, Research Report4196-1. http://tcd.tamu.edu/Documents/4196-1.pdf

� Texas Design Guidelines for At-Grade Intersections NearHighway-Railroad Grade Crossings.

INTERSECTION SAFETY RESOURCES April 2004 2

For more information contact:

FHWA Office of SafetyContact: Hari Kalla Phone: 202-366-5915http://safety.fhwa.dot.gov/programs/intersections.htm

Institute of TransportationEngineersContact: Edward StollofPhone: 202-289-0222 x132http://www.ite.org