Identification of High-Crash Locations
A first step in the problem-solving process of improving bicycle safety and mobility is to identify locations or areas where bicycle crash problems exist and where engineering, education, and enforcement measures will be most beneficial. Mapping the locations of reported bicycle crashes in a neighborhood, campus, or city is a simple method of identifying sites for potential bicycle safety improvements. One method of analyzing crash locations is through computerized Geographic Information Systems (GIS) software. This type of map can help transportation engineers and planners focus safety improvements on intersections, corridors, or neighborhoods where bicycle crashes have occurred.
Several issues should be considered when creating GIS maps of reported crash locations. First, the volumes of bicycle and motor vehicle traffic that use each location will affect reported crash density.
Second, bicycle crashes may not be reported frequently enough to establish a pattern of unsafe bicycling locations. In either case, other steps may improve the identification of unsafe locations for bicycling. These include:
- Using bikeability checklists.1
- Noting bicycle and driver behavior and examining roadway and bicycling characteristics at specific sites.
- Observing and recording the number of bicycle-motor vehicle conflicts at specific sites.2
- Mapping locations known to have a high potential for bicycle crashes in an area.
- Calculating a bicycle level of service.3
In regard to conflicts, a number of studies have been performed using bicycle-motor vehicle conflicts as a study variable in lieu of crash data, and the technique is described within the body of the report.2 A conflict is usually defined as a sudden change in speed or direction by either party to avoid the other. In regard to bicycle level of service, one popular tool is the Bicycle Compatibility Index, where a user inserts values for several easily obtained variables to determine the comfort level (level of service) for bicyclists on a midbock section of a street or roadway.3 An intersection level of service for the bicycle through movement has also been developed.4 Another intersection rating tool is under development for the Federal Highway Administration (FHWA) for both bicyclists and pedestrians. The bicyclist portion considers the through movement, right turns, and left turns.5
