An Examination of the Safety of Signalized Intersections in Consideration of Nearby Access Points

Effective access management is critical to the safe and efficient operation of roadway corridors. Access management is particularly important near signalized intersections, where adjacent driveways exacerbate the crash risks created by conflict points at the primary intersection. This study examines the relationship between crash risk and access spacing in the vicinity of 415 signalized urban intersections. The frequency of access points near each signalized intersection of interest was collected to examine the differences in experienced crash frequency over a five-year period. Additional information about each access point was collected, including details of turning movement restrictions and estimated driveway volumes. A series of buffers of varying radii were considered to examine how crash rates varied based upon the spatial proximity of access points to each signalized intersection. In addition, traffic volume and roadway geometric information was collected and utilized as a part of this evaluation. A series of crash prediction models were estimated to discern how crash rates varied based upon the access point density on the intersection approaches along the major (i.e., higher volume) roadway. As the number of access points increased, the crash rates also increased. This relationship was consistent in direction, but varied in magnitude, depending on the size of the buffers, which varied in radius from 50 ft to 600 ft at 50-ft intervals. The number of crashes by location was also shown to vary based upon the number of travel lanes, the number of intersection legs, and the land use type of the adjacent driveways.