2. Government Accession No. 3. Recipient's Catalog N

13. Type of Report and Period Covered

A Comparative Analysis of BicycleLanes Versus Wide Curb Lanes:Final Report

PUBLICATION NO. FHWA-RD-99-034

DECEMBER 1999

Research, Development, and TechnologyTurner-Fairbank Highway Research Center6300 Georgetown Pike

McLean, VA 22101-2296

13. Type of Report and Period Covered

Technical Report Documentation Page

1. Report No.

2. Government Accession No.

3. Recipient's Catalog No.

FHWA-RD-99–034

4. Title and Subtitle

5. Report Date

A COMPARATIVE ANALYSIS OF BICYCLE LANES VERSUS WIDE CURB LANES: FINAL REPORT

7. Author(s)

6. Performing Organization Code

William W. Hunter, J. Richard Stewart, Jane C. Stutts, Herman

H. Huang, and Wayne E. Pein

9. Performing Organization Name and Address

8. Performing Organization Report No.

10. Work Unit No. (TRAIS)

University of North Carolina

Highway Safety Research Center730 Airport Road, CB #3430Chapel Hill, NC 27599

12. Sponsoring Agency Name and Address

11. Contract or Grant No.

DTFH61-92-C-00138

13. Type of Report and Period Covered

Office of Safety and Traffic Operations Research & DevelopmentFederal Highway Administration6300 Georgetown PikeMcLean, VA 22101-2296

15. Supplementary Notes

Final Report

March 1995 - May 1998

14. Sponsoring Agency Code

Contracting Officer’s Technical Representative (COTR): Carol Tan Esse, HSR-20Subcontractor: Bicycle Federation of America

16. Abstract

This report is a comparative analysis of bicycle lanes (BLs) versus wide curb lanes (WCLs). The primary

analysis was based on videotapes of almost 4,600 bicyclists (2,700 riding in BLs and 1,900 in WCLs) in the cities ofSanta Barbara, CA, Gainesville, FL, and Austin, TX, as the bicyclists approached and rode through eight BL andeight WCL intersections with varying speed and traffic conditions. The intent was to videotape bicyclists whoregularly ride in traffic. The videotapes were coded to learn about operational characteristics (e.g., intersectionapproach position and subsequent maneuvers) and conflicts with motor vehicles, other bicycles, or pedestrians. Aconflict was defined as an interaction between a bicycle and motor vehicle, pedestrian, or other bicycle such that atleast one of the parties had to change speed or direction to avoid the other. Both bicyclist and motorist maneuvers inconflict situations were coded and analyzed. This covered maneuvers such as a bicyclist moving incorrectly from thebicycle lane into the traffic lane prior to making a left turn, or conversely, a motor vehicle passing a bicyclist and thenabruptly turning right across its path. Bicyclist experience data were also collected separately from the videotaping ateach of the 16 data collection sites in each city through use of a short oral survey. Slightly more than 2,900 surveyswere completed. These data were analyzed to learn about the age, riding habits, and experience levels of thebicyclists riding through these intersections. Bicycle-motor vehicle crash data were also analyzed to determine ifthere were parallels to the videotape data.

In addition to this final report, there is a separate report (FHWA-RD-99-035) containing a synopsis of the keyfindings of the final report and recommended countermeasures, as well as a guidebook (FHWA-RD-99-036) aboutinnovative bicycle accommodations.

17. Key Words:

18. Distribution Statement

Bicycle lane, wide curb lane, bicycle operations, bicyclemaneuvers, conflicts

No restrictions. This document is available to the public through the National Technical InformationService, Springfield, Virginia 22161

21. No. of Pages

22. Price

19. Security Classif. (of this report)20. Security Classif. (of this page)

UnclassifiedUnclassifiedvii, 104

Reproduction of form and completed page is authorized

13. Type of Report and Period Covered

Table of Contents

Chapter 1 - Introduction .......................................1

Background ..................................................1Objective and Scope ............................................2Brief Literature Review.........................................3Bicycle lanes ...............................................3Wide curb lanes ............................................4Other facilities .............................................5Intersection treatments......................................5Organization of the Report ......................................9

Chapter 2 - Methods .........................................11

Overview ....................................................11City Selection ................................................11Santa Barbara, California ...................................12Gainesville, Florida ........................................12Austin, Texas .............................................12Site Characteristics ...........................................12Videotaping of Bicyclists .......................................14Bicyclist Experience Data ......................................15Coding of Videotape Data ......................................16Creation of Project Database ...................................16Coding and Analysis of Crash Data ..............................16

Chapter 3 - Results ...........................................19

Bicyclist Characteristics .......................................19Videotape data ............................................19Bicyclist experience survey results ............................21Midblock Actions .............................................23Movements ...............................................23Midblock spacing between bicycles and motor vehicles ...........25Behaviors ................................................27Intersection Actions ...........................................29Movements ...............................................29

13. Type of Report and Period Covered

Behaviors ................................................34Conflicts ....................................................36Midblock .................................................36Intersections ..............................................39Midblock and intersection combined conflict rates ...............43Statistical Modeling of Conflicts Data ............................43Analysis of midblock bike/motor vehicle conflicts ................43Intersection car/bike /motor vehicle conflicts ....................46Reanalysis of conflicts based on data from more

“typical” sites ............................................49A Clinical Analysis of High Conflict BL and WCL Sites ..............50Midblock conflicts .........................................50Intersection conflicts .......................................55Examination of Serious Conflicts ................................62Serious midblock conflicts ...................................62Serious intersection conflicts .................................62Comparisons with Crash Data ...................................66

Chapter 4. Discussion ........................................69

Summary of Main Results ......................................69Bicyclist characteristics .....................................69Midblock movements .......................................69Statistical modeling of spacing between bicycles

and motor vehicles ........................................69Intersection movements .....................................70Midblock conflicts .........................................71Intersection conflicts .......................................71Statistical modeling of conflict data ............................72Clinical examination of high conflict rate sites ...................72Clinical examination of serious conflicts ........................73Comparisons with crash data .................................73Further Comment .............................................73Level of experience ........................................73Wrong-way riding ..........................................74Turning and other maneuvers at intersections ...................74Conflicts .................................................74Recommended Countermeasures for Certain High Conflict

Rate Problems ..............................................75Parked motor vehicles ......................................75

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Driveways and intersecting streets ............................76Additional lanes at intersections ..............................77Conclusions ..................................................78

Appendix A - Experience Form ...............................81Appendix B - Coding Form ...................................83References ........................................95

13. Type of Report and Period Covered

viTable of Contents

List of Figures

Figure 1. Typical bike lane .....................................................1Figure 2. Typical wide curb lane .................................................1Figure 3. Oregon bike lane standards ............................................3Figure 4. Oregon wide curb lane standards ........................................4Figure 5. Profiled marking at a bus stop to separate bicyclists from bus passengers.......5Figure 6. Oregon rumble strip ..................................................6Figure 7. BL dashed to intersection ..............................................6Figure 8. Colored bicycle crossing in Montreal .....................................7Figure 9. A European raised and painted bike path (crossing) .........................7Figure 10. T-intersection marking in Denmark .....................................7Figure 11. Modern roundabout ..................................................8Figure 12. Bike box ...........................................................8Figure 13. Recessed stop line ...................................................9Figure 14. Map of project cities................................................11Figure 15. Typical data collection setup ..........................................15Figure 16. BL and WCL intersection types .......................................47Figure 17. Standard no parking signs for bike lanes................................76Figure 18. Double striped BL with parking .......................................76Figure 19. Combination BL with parking T’s ......................................76Figure 20. Typical conflict situations at a driveway crossing a sidewalk ................76Figure 21. Example of traffic splitting ...........................................77Figure 22 Dashed BL stripe at right-turn situation .................................78Figure 23. European bike box ..................................................78

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Table of Contentsvii

List of Tables

Table 1. Videotaped bicyclist characteristics......................................20Table 2. Experience survey bicyclist characteristics................................21Table 3. Experience survey riding characteristics .................................23Table 4. Midblock actions.....................................................24Table 5. Model for distance from curb for bikes not being passed .....................26Table 6. Model for distance from curb for bikes being passed .......................27Table 7. Model for distance between bikes and passing motor vehicles ................27Table 8. Midblock behaviors...................................................28Table 9. Intersection actions...................................................30Table 10. Intersection movements ..............................................32Table 11. Intersection turning information .......................................33Table 12. Intersection behaviors ...............................................35Table 13. Midblock conflict information .........................................37Table 14. Midblock conflict bicycle and motor vehicle actions .......................38Table 15. Intersection conflict information .......................................40Table 16. Intersection conflict bicycle and motor vehicle actions .....................42Table 17. Example of model results for midblock conflicts ...........................44Table 18. Midblock conflicts model including bike lane width ........................44Table 19. Bike lane width by midblock conflicts ...................................45Table 20. Intersection conflicts by facility type and bicyclist movement ................46Table 21. Intersection conflicts by intersection type for straight through and

right turning bicyclists ...............................................48Table 22. Most frequent occurring crash types rank ordered in each of the three

study sites, based on 1995 police-reported crash data ......................67

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Chapter

1Introduction

Background

A number of recent events renders astudy of bicycle facilities as appropriate andtimely. The passage of the 1991 IntermodalSurface Transportation Efficiency Act

(ISTEA) legislation meant a variety of fundscould be more readily used by local and stateofficials to plan and build such facilities. Indications are that many governments andagencies have taken advantage of the oppor-tunity. Publication of the National Bicyclingand Walking Study in 1994 with the U.S.Department of Transportation (USDOT)goals of doubling the percentage of tripsmade by bicycling and walking and

simultaneously reducing by 10 percent thenumber of bicyclists and pedestrians injuredor killed in traffic crashes adds emphasis tothe need to accommodate non-motoristswith well-designed facilities. User surveyrespondents have clearly stated that morefacilities are desired and will increase theamount of travel by bicycle.

In addition to the recent activitiesmentioned above, during the past 20 yearsbicycle facilities have been planned andimplemented in communities now

considered as pro-bicycling, including Seattle,WA; Davis and Palo Alto, CA; Madison, WI;Eugene and Corvallis, OR; Boulder, CO;Gainesville, FL; Tucson, AZ; and others. These communities tend to have a localbicycle coordinator and bicycling advisorycommittee in place. Not all of the

implemented facilities have been ideallyconstructed. However, what has tended tooccur in all of these communities is thatmotorists have adapted to bicyclists wherebicycle facilities have been implemented,and most facilities appear to

function effectively, although not withoutsome problems. What has not beendone and reported to the bicycling andtraffic engineering community is a thoroughevaluation of the various kinds of facilities incommunities like these.

Given the information presented above,considerable effort was devoted to decidingwhat kinds of bicycle facilities should beevaluated in this project. A long-standingissue in the bicycling community centers onwhether bicycle lanes or wide curb lanes are

Figure 1. Typical bike lane.

preferable. A bicycle lane (BL) is a portionof a roadway that has been designated bystriping and pavement markings for thepreferential or exclusive use of bicyclists(figure 1). BL width is normally in the range of 1.2 to 1.8 m. A wide curb lane (WCL) isthe lane nearest the curb that is wider than astandard lane and provides extra space sothat the lane may be shared by motor

vehicles and bicycles (figure 2). Thus, WCLs

13. Type of Report and Period Covered

may be present on normal two-laneroadways or on multilane roadways. A desirable width for WCLs is 4.3 m. Laneswider than 4.6 m sometimes result in theoperation of two motor vehicles side byside. Many bicyclists report feeling saferwhen riding on BLs, while BL opponentsventure that these facilities make it difficultfor bicyclists to handle turning maneuvers atintersections, especially left turns. WCLadvocates believe that these wider lanesencourage cyclists to operate more like

motor vehicles and thus lead to more correctmaneuvering at intersections. Bothperspectives have merit and should be

addressed in any evaluation of these facilities.Because a WCL is a wider-than-normal

traffic lane that is shared with motor vehicles,some do not refer to this layout as a bicyclefacility. However, for purposes of this study,both BLs and WCLs will be referred to asbicycle facilities.

The debate over whether BLs or WCLsare preferable has been heated for manyyears and is not unlike the seat belts versus airbags dichotomy that prevented a concertedapproach to the promotion of occupantrestraints in the United States in the 1970sand 1980s. While both BLs and WCLs areacceptable facilities in many locations, thedebate has sometimes forced decisionmakers to choose which facility type theyprefer, to the exclusion of the other. Morebicycle facilities might be in place in this

country except for this long-standing divisionof opinion. Because of the interest in BLsand WCLs, it was decided to make thesefacilities the focus of this project, with anemphasis on operations and interactionsbetween bicyclists and motorists atintersections.

Objective and Scope

The primary objective of the currentstudy was a comparative analysis of BLs

Chapter 1

versus WCLs. Bicyclists riding in either a BLor WCL were videotaped as theyproceeded through BL and WCL

intersections with varying speed and trafficconditions in three U.S. cities. Thevideotapes were coded to learn aboutoperational and safety characteristics.

Operational characteristics pertained to howbicyclists maneuvered through the sites,while safety characteristics pertained to

conflicts with motor vehicles, other bicycles,or pedestrians. A conflict was defined as aninteraction between a bicycle and motorvehicle, pedestrian, or other bicycle such thatat least one of the parties had to changespeed or direction to avoid the other.Exposure/experience data were also

collected separately from the videotaping ateach of the data collection sites in each citythrough use of a short oral survey.

Information was obtained about the age,gender, race, helmet use, levels ofexperience, etc., of the bicyclists ridingthrough these intersections.

A secondary study objective was todevelop a guidebook of current innovativebicycling activities, with a primary focus onintersection treatments that pertained to BLsand WCLs. The innovative treatment“shopping list” included advance stop bars(often called bike boxes) where bicycles areallowed to proceed ahead of motor vehicletraffic at an intersection; painting a modifiedversion of the bicycle logo near the curb ina WCL to alert drivers that bicycles wouldbe operating in this space; colored

Figure 2. Typical wide curb lane.

2

13. Type of Report and Period Covered

pavement designating the appropriate pathfor the bicycle through an intersection; trafficcalming measures like diagonal diverters andspeed humps with "slots" in the pavementfor bikes and buses; bicycle traffic signals;combination bus/bike lanes; differenttechniques for separating bike lanes; andothers. The Bicycle Federation of America(BFA) was responsible for locating therelevant examples and developing

appropriate descriptions. This guidebook isone of the final products of this contract.

Brief Literature Review

The National Bicycling and WalkingStudy (1994) established USDOT goals ofdoubling the percentage of trips made bybicycling and walking, while simultaneouslyreducing the number of bicyclists and

pedestrians injured or killed in traffic crashesby 10 percent. To realize these goals, ourtransportation system needs better ways toaccommodate bicycling and walking. The1991 ISTEA allowed cities and States tospend Federal transportation funds onfacilities for bicycling and walking. Local

Figure 3Source: Oregon Bicycle and Pedestrian Plan,. Oregon bike lane standards.

1995

bicycle planners can choose among

conventional roadway treatments such as

3

BLs and WCLs, and more innovative

treatments such as modern roundabouts andadvanced stop bars (popularly referred to asbike boxes in the United States).

Bicycle lanes

A bicycle lane is a section of the roadwaythat is delineated from the adjacent motorvehicle travel lane by a stripe. BLs are

usually along the right edge of the roadway,but may be designated to the left of parkingor right-turn lanes. Recommended widthsfor bicycle lanes (figure 3) are generally 1.2to 1.8 m

(see, for example, North Carolina DOT,1994; New Jersey DOT, 1995; OregonDOT, 1995). A Dutch design manual(C.R.O.W., 1994) suggests 2.0 m so thatbicyclists can ride side-by-side, and anotherDutch study (Botma and Mulder, 1993) callsfor a width of 2.5 m when the 1-hour peakvolume exceeds 150 bicycles to allowbicyclists to pass one another. In anationwide survey of U.S. cyclists takenmany years ago, 85 percent considered BLs

Chapter 1

13. Type of Report and Period Covered

wider than 1.8 m to be adequate; only 41percent considered BLs narrower than 1.5 mto be adequate (Kroll and Sommer, 1976).

Ninety-three percent of U.S. cyclistsusing BLs thought the street was safer withthe lanes than without them, although therewas no conclusive evidence that they actuallyimproved cyclist safety (Kroll and Sommer,1976). Two other studies credited BLs withreducing bicycle-motor vehicle crashes bymore than half in Corvallis, Oregon, and bytwo-thirds in Eugene, Oregon (Ronkin, nodate; City of Eugene, 1980). The installationof BLs along a one-way arterial pair inMadison, Wisconsin, was associated with asignificant increase in the number of crashesassociated with turning movements;

however, crashes decreased sharply after thefirst year of operation (Smith and Walsh,1988).

A manual prepared for the FederalHighway Administration (FHWA) usesvarious factors to make recommendationsfor roadway design treatments foraccommodating bicyclists. The factors

include definitions of design bicyclists, typeof roadway, traffic volume, average motorvehicle operating speeds, traffic mix, on-street parking, sight distance, and number ofintersections and entrances. BLs are oftenrecommended when most bicyclists on theroute are less experienced (Wilkinson, Clarke,Epperson, and Knoblauch, 1994).

In Denmark, roadway stretches withBLs or bicycle paths tended to have a lowerfrequency of crashes involving cyclistcasualties than stretches without lanes orpaths (Herrstedt et. al., 1994). Anotherevaluation of BLs in Denmark found nochange in the number of overall crashes orbicycle-motor vehicle crashes at signalizedjunctions, but did find an increase in thenumber of bicycle-motor vehicle crashes atpriority junctions (unsignalized junctions,usually signed, where one roadway has

Chapter 1

priority over the other). There was also areduction in all crashes on stretches (thesections of roadway between intersections)(Jensen, 1997).

The presence of a stripe separatingbicyclists and motorists (as with a BL orpaved shoulder) has been shown to result infewer erratic driver maneuvers, morepredictable bicyclist riding behavior, andenhanced comfort levels for both groups ofusers (Harkey and Stewart, 1997; Kroll andRamey, 1977; McHenry and Wallace, 1985).The principal findings from the 1997 studyof bicyclists riding in midblock situations byHarkey and Stewart for the Florida DOTwere the following:

!The separation distance betweenbicyclists and motorists was about 1.8 m andvaried only a small amount by facility type(BLs, WCLs, and paved shoulders).

!The distance between the bicyclistand the edge of the roadway wasconsiderably greater on BL and paved

shoulder facilities (0.8 m) than on WCLs (0.4m).

!Motor vehicles moved about 0.4 mfurther to the left when passing a bicyclist onWCLs compared with BL and pavedshoulder facilities.

! Motor vehicle encroachment into theadjacent lane to the left when passing abicycle was much greater on WCLs (22.3percent) than on BL (8.9 percent) and pavedshoulder facilities (3.4 percent).

! For a BL facility, the change in lateralposition of the motor vehicle when passing abicycle was approximately 0.3 m regardlessof BL width.

Wide curb lanes

Wide curb lanes can accommodate bothbicyclists and motorists and allow sufficientroom for passing. These are sometimesdesignated when right-of-way constraints

4

13. Type of Report and Period Covered

Chapter 1

5

preclude the installation of “full width” BLs. WCLs should be 4.0 to 4.6 m wide (figure 4) avoid road hazards or to overtake otherbicyclists, motor vehicles, or pedes- triansto provide enough width for lane sharing but not so much width that motorists formtwo lanes at intersections (McHenry andWallace, 1985). Wilkinson et al. (1994)recommend WCLs in many kinds of

roadway situations where most bicyclists areexperienced riders. The Harkey and Stewartstudy (1997) performed for the FloridaDOT showed that motorists encroach intothe adjacent lane of traffic significantly moreoften when WCLs are used as comparedwith BLs.

At present there appears to be a trendtoward more use of BLs at the State andlocal levels, perhaps due to preferences citedby bicyclists. (See, for example, a statement inthe Florida Bicycle Facilities Planning and DesignManual (Florida DOT, 1995) that WCLsshould be used as a last resort because “onlyfive percent of bicyclists feel comfortableusing these facilities.”) On the other hand, theNorth Carolina DOT (1994) refers to a1970s FHWA publication to list principalproblems with BL applications in its bicyclefacilities planning and design guidelines,including: (1) provision of inadequate lanewidth or use of unrideable street surface asthe BL area, (2) abrupt termination of lanesat hazard or constraint situations, creating afacility that leads bicyclists to a trap, as well astransitions that force awkward bicyclistmovements at other termination points, (3)use of non-standard and poorly visible lanedemarcation signs and markings that createuncertainties in motorist and bicyclist

understanding of lane presence and purpose,(4) lane configuration and lane use ordinancesthat prevent the bicyclist from establishingproper position with respect to motorvehicle traffic at intersections, as well as formid-block turns into driveways, and (5) laneuse ordinances that conflict with reasonablebicyclist desires to leave the lane in order to

occupying the bike lane.

Other facilities

A combined bus and bike lane in Torontowas found to increase bicycle traffic andlower accident rates. More than 75 percent

Figure 4. Oregon wide curb lanestandards.

Source: Oregon Bicycle and Pedestrian Plan,1995

of riders felt safer riding along the new busand bike lane (Egan, 1992). Combinedbus/bike lanes should be 3.1 to 3.7 m wide(Harrison, Hall, and Harland, 1989). Withbus/bike lanes, the potential exists forconflicts between buses and bikes at thecrossing points. One design places a bicyclelane to the right of the through traffic lanesand to the left of the bus and right-turn lane. This allows bicyclists to ride without leap-frogging past stopped buses (Berchem andSomerfeld, 1985).

Other Danish designs are aimed at

reducing conflicts between bicyclists and buspassengers due to the high incidence ofcrashes in bus stop areas. These designsinclude: (1) a pedestrian crossing combined withprofiled markings (figure 5); (2) a profiled

marking on the offside of the bicycle path; and (3) apainted pattern with a visual brake. The intentwas to use pavement markings to highlight the conflict area at bus stops and move

13. Type of Report and Period Covered

bicyclists away from the passengers alightingfrom buses. The proportion of cyclists whowait for bus passengers to cross the bicyclepath did not change with any of the designs.

Figure 6. Oregon rumble strip.

Source: Oregon Bicycle and Pedestrian Plan,1995

All three designs reduced the speed of

cyclists when there was a bus at the bus stop. The distance from where cyclists first reactedto a bus to the nearest conflict point

increased. The number of serious conflictsdecreased with the painted pattern(Herrstedt, 1994).

The expected number of bicycle-motorvehicle crashes is much lower when bicyclistsride along paved highway shoulders than whenbicyclists and motorists share the travel lanes(Khan and Bacchus, 1995). Operationally ithas been shown that paved shoulders

essentially function like BLs with respect tobicycle and motor vehicle interactions (i.e.,the stripe separating bicyclists from motoristsresults in a lower risk environment for bothmodes of travel (Harkey and Stewart, 1997).

One potential hazard is that an inattentiveor sleepy driver may drift off the roadwayonto the shoulder and strike a bicyclist ridingon the shoulder. Although there isconsiderable debate regarding the mosteffective design, a shoulder rumble strip (figure6) is an efficient device to waken

drivers who are drifting off the roadway(Garder, 1995). On highways with posted

Chapter 1

Figure 5. Profiled marking at abus stop to separate bicyclistsfrom bus passengers.

Source: Safety of Cyclists in UrbanAreas, 1994

speeds of less than 100 km/h, a minimumwidth of 1.5 m of paved shoulder issufficient space to accommodate both arumble strip and bicyclist travel (Khan andBacchus, 1995).

In the Netherlands, separate bicycle pathsare recommended when motor vehiclespeeds exceed 50 km/h or when trafficvolumes exceed 1,200 vehicles per hour. One-way cycle paths should be at least 1.8 mwide, and two-way cycle paths should be 2.8m wide (Diepens and Okkema TrafficConsultants, 1995). In an earlier survey ofU.S. cyclists, bike paths were rated as beingsafer than bike lanes, and most thought thatpaths wider than 2.8 m were “good” (Krolland Sommer, 1976).

Intersection treatments

Intersections and intersection-related locationsaccount for 50 to 70 percent of bicycle-motor vehicle crashes (Hunter, Stutts, Pein,and Cox, 1996). Countermeasures such asgrade separation can be adopted to reduceintersection conflicts between bicycles andmotor vehicles. More than 50 interchanges

6

13. Type of Report and Period Covered

in Beijing, China, provide for gradeseparation between bicyclists and motorvehicles (Liu, Shen, and Ren, 1993; Burden,Wallwork, and Guttenplan, 1994).

Figure 9. A European raised andpaintedSource: Oregon Bicycle and Pedestrian Plan, bike path (crossing).

1995

Grade separation is expensive, though,and thus lower cost, at-grade treatments aremore widely used. For example, bicycle pathcrossings of roadways can be offset awayfrom the intersection to enhance bicyclists’view of motorists (NCHRP, 1976). On onestreet in Cupertino, California, a BL stripewas dashed to guide cyclists riding in the BL(next to the curb) to the left of right-turningvehicles (Grigg, no date). The Florida DOT

7

(1995) is one of a number of State DOTsrecommending that BLs be discontinued ordashed in advance of an intersection, so thatbicyclists and motorists can merge (figure 7). Right-angle bicycle crossings with good sightlines are recommended at intersections.At five intersections in Montreal, coloredbicycle crossings were installed (figure 8), with the pavement colored blue at bicycle pathcrossing points. After the markings werepainted, bicyclists were more likely to obeystop signs and to stay on designated cyclepath crossings. Improved bicyclist behaviorled to a decline in the level of conflictbetween cyclists and motorists (Pronovostand Lusginan, 1996). In Denmark, the

marking of bicycle travel paths (raised overpasses) at

Figure 7. BL dashed to intersection

.

signalized junctions resulted in 36 percentfewer accidents with motor vehicles and 57percent fewer cyclists who were killed orseverely injured (Jensen, 1997). Some ofthese crossings also used blue color on thepavement.

A raised and painted bicycle path (crossing)(figure 9) introduced at 44 intersections in Gothenburg, Sweden, reduced motor

vehicle speeds (by 35 to 40 percent for right-turning motor vehicles) and increased cyclistspeeds (by 10 to 15 percent). The safetyimprovement was estimated by using aquantitative model and by surveying

Chapter 1

13. Type of Report and Period Covered

bicyclists and experts. The model estimatedthe combined effect of lower motorist

speeds and higher bicyclist speeds to be a 10percent reduction in the number of bicycle-motor vehicle crashes. Bicyclists perceived a20 percent improvement in safety after thebicycle path was raised and painted. Expertsestimated a 30 percent improvement insafety. However, the authors suggested thatthe total numbers of crashes should beexpected to increase due to a 50 percentincrease in bicyclists using the improvedcrossings (Leden, 1997). A follow-on paperusing a Bayesian approach for combining theresults of the model and surveys estimated arisk reduction of approximately 30 percentattributable to the raised and painted crossing(Gårder, Leden, and Pulkkinen, 1998).

A different report based on a review ofthe literature, interviews with bicyclists, andexpert opinion concluded that the crash riskwould increase by about 40 percent when abicycle path is added at a signalized

intersection (Leden, Gårder, and Thedéen,

Figure 11. Modern roundabout.

Sourcein press:

Innovative Bicycle Accommodations,1993).

Profiled pavement marking aimed atreducing the lateral distance betweenmotorists and cyclists and increasing

attentiveness between bicyclists and motoristschanged motorist and cyclist behavior at T-intersections and four-way intersections inDenmark (figure 10).

Chapter 1

Profiled markings were placed to guide

approaching cyclists closer to the travel lanes. At the intersection, the cyclists were guidedaway from the travel lanes. More motoristsadapted their speeds to the cyclists’ speedsand stayed behind the stop line. Motoristswere less likely to turn right in front ofcyclists. At T-intersections, cyclists becamealert earlier (Herrstedt et al., 1994).

Many bicycle-motor vehicle crashes atroundabouts occur when motorists cut in frontof bicyclists or fail to yield the right-of-way. Small roundabouts with flared entry roadsare the most dangerous design, whereaslarge roundabouts are the most feared bybicyclists. Crash rates for bicyclists atroundabouts in the United Kingdom aretwo to three times higher than thoseexperienced by bicyclists at traffic signal-controlled intersections. Mini-roundaboutshave a much better crash record, similar tothat of four-way traffic, signal-controlledintersections. Lane markings, warning signs,sharper entry angles, and visibility

improvements have helped reduce bicyclistcrashes in roundabouts (figure 11). Smaller roundabouts, where motorists cannot

overtake bicyclists, are recommended (Allottand Lomax, 1993; Balsiger, 1995). In acomparison of Swedish, Danish, and Dutchroundabouts, a separate cycle path with an

Figure 10. T-intersection marking inDenmark.

Source: Safety of Cyclists in Urban Areas, 1994

8

13. Type of Report and Period Covered

ordinary cycle crossing was found to be thesafest design when motor vehicle trafficflows were large, compared with a cycle lanewithin the roundabout or no specific bicyclefacility at all (Brüde and Larsson, 1996). Results were based on observed versusexpected crashes, with expected crashesobtained from a predictive model. Theauthors noted that data were limited. Aroundabout on the University of Californiaat Davis campus allows five times as manycyclists to pass through, compared withwhen the intersection was controlled by stopsigns, and bicycle crashes that result in injury

Figure 13Source: Safety of Cyclists in Urban Areas, 1994

. Recessed stop line.

are rare (Burden, Wallwork, and Guttenplan,1994).

On roads with marked BLs, an advancedstop line (ASL) or bike box may be placed inthe BL at a signalized intersection. The bikebox is placed in front of the motor vehiclestop line to give bicyclists a space to wait infront of motorists and to allow them to passthrough first when the green phase starts. Being in the box makes bicyclists morevisible to motorists and can reduce conflictswith turning motor vehicles (figure 12).Under a single-signal design, one trafficsignal is placed at the box. With a two-signaldesign, used in the United Kingdom,motorists are held by a red signal, while aspecial green signal directs bicyclists ahead tothe box (U.K. Department of Transport,1993; Zegeer et al., 1994).

9

Bike boxes have worked successfully onroads in the United Kingdom with up to1,000 vehicles per hour passing through theintersection. Wheeler (1995) and Wheeler etal. (1993) monitored schemes at nineintersections. Two-thirds or more of thebicyclists used the cycle lane and the reservedwaiting area. Signal violations by bicyclistswere less than 20 percent. As many as 16percent of motorists encroached into theBLs. At one intersection, more than half ofall lead motorists encroached into thecyclists’ reserved waiting area. The single-signal design is likely to be as effective as thetwo-signal design if a mandatory cycle laneand a distinctly-colored road surface in thecyclist areas are used. In Denmark, recessedstop lines (figure 13) for motor vehicles significantly reduced the number of crashesbetween right-turning motorists and cyclistsgoing straight through the intersection(Herrstedt et al., 1994).

Organization of the Report

The results of this research are providedin three documents. This final report

contains the comprehensive results pertainingto operations and conflicts. A researchsummary provides planners, engineers, andpedestrian/bicycle coordinators a tool with

Figure 13.

Bike box.

Chapter 1