The 2010 Highway Safety Manual (HSM) provides methods for predicting the number of motor vehicle crashes on various roadway facilities. However, it includes only a rudimentary method for predicting the number of bicycle-related crashes. Despite research demonstrating that bicycle volume is an important factor in estimating number of bicycle crashes, the method does not include the volume of bicyclists using the roadway.
To remedy this, this project will investigate the potential of various simplified methods to include bicycle volumes in future versions of the HSM. By studying locations where bicycle traffic volumes, motor vehicle traffic volumes, bicycle collisions, and roadway facility types are known, the research team will study how best to predict bicycle collisions. This includes creating bicycle specific safety performance functions. The project will then examine how and if these methods could be simplified for use in future versions of the HSM. Potentially, bicyclist volumes could be simplified into high, medium, and low categories in order to reduce the need for difficult to find data. The impact of different facility types will also be investigated, such that a generalized table appropriate for HSM users can be generated.
While this research cannot provide a final HSM-ready version, it will investigate locations where data are available and could lead the way in developing such. In addition, this work will investigate the impact of cyclist volume on bicyclist collision risk. This work could have an impact on cyclist safety by facilitating a better understanding of the impact of facility design on bicyclist safety by separating out the effect of bicycle volume on predicted bicycle crashes.