What are the safety issues for shared use pathways?

A 12-foot wide shared path with uses separated in Boulder, Colorado.

Image: City of Boulder

Physically separated from roadways, shared use pathways usually accommodate a variety of two-way nonmotorized travel. Users may include bicyclists, pedestrians, wheelchair users, people with baby strollers, in-line skaters, runners, and sometimes equestrians. Although the AASHTO Guide for the Development of Bicycle Facilities (1999) discourages side paths, communities build them because significant numbers of bicyclists want to travel in a dedicated right of way and other alignments are not feasible.

A raised right turn crossing of a shared use pathway in Boulder, Colorado.

Image: City of Boulder

Passing slower users in the same direction and two-way traffic flow are two primary safety issues, particularly where there is a high volume of pathway users. The AASHTO Guide offers design criteria for constructing shared pathways. Minimum pathway width should be 10 feet with two additional feet of clearance on each side. If a mix of users or high volume is expected, the Guide recommends that the pathway be widened to 12-14 feet and that uses be separated. In addition, the pathway should be as straight and direct as practical while still providing an interesting and safe user experience; users should be encouraged to travel on the right and pass on the left; yellow center line stripes and "No Passing Zone" signs should be used only at locations with limited sight distance to allow for free-flow along other sections of the pathway.

Typical treatment of a driveway crossing a shared use pathway in Boulder, Colorado.

Image: City of Boulder

Another safety issue is visibility of the pathway corridor and other users during nighttime travel. State laws usually require a bicycle to be equipped with a mounted white headlamp and rear red reflector from dusk to dawn. Non-wheeled users may not be as visible as bicyclists. This issue can be addressed through education and outreach to raise runners' and walkers' awareness about the importance of wearing reflective clothing and/or carrying a headlamp/red blinking light; enforcing regulations requiring lights and reflectors; or illuminating the pathway.

Shared use pathways running parallel and immediately adjacent to a roadway are referred to as side paths and present additional safety issues at driveway and intersection crossings. Motorists do not expect bicyclists to travel in the opposite direction as roadway traffic, which increases the potential for conflict between bicyclists and motorists. At intersections, there is increased potential for conflict between bicyclists traveling straight through and motorists turning right or left, as these users share the same green signal time. Constructing raised right turn bypass islands may improve visibility and reduce this potential for conflict. Protected left turn phasing will reduce the potential for conflict with left-turning vehicles. Installing standard warning signs and marked crosswalks at intersections and high conflict driveways also addresses these safety issues.

Other resources and information:

American Association of State Highway and Transportation Officials. (1999). Guide for the Development of Bicycle Facilities, 3rd edition. Washington, D.C.: AASHTO.

US Department of Transportation Federal Highway Administration. (2006). Evaluation of Safety, Design, and Operation of Shared-Use Paths: Final Report. (FHWA-HRT-05-137). http://drusilla.hsrc.unc.edu/cms/downloads/Eval_SharedUsePaths_Final.pdf

US Department of Transportation Federal Highway Administration. (2006). Shared-Use Path Level of Service Calculator: A User'sGuide. (FHWA-HRT-05-138). http://drusilla.hsrc.unc.edu/cms/downloads/SharedUse_LevelofService.pdf

"Is it true that trails and bike paths are more dangerous than roads?" http://www.bicyclinginfo.org/faqs/answer.cfm?id=1

Also search the Online Library at www.bicyclinginfo.org for case studies and more resources related to shared use pathways.