Bicyclist Intersection Safety Index

Each year many bicyclists are injured or killed in intersection-related crashes with motor vehicles. The objective of this study was to develop a macrolevel bicycle intersection safety index (Bike ISI) that would allow engineers, planners, and other practitioners to use known intersection characteristics to prioritize intersection approaches with respect to bicycle safety proactively. Using variables that indicate a higher probability of risk for bicyclists, the Bike ISI identifies which intersection approaches have the highest priority for bicycle safety improvements within a particular jurisdiction. Using video data and online ratings surveys, this study obtained data on avoidance maneuvers and safety ratings at 67 intersection approaches and developed a Bike ISI model that incorporated both measures of safety. The Bike ISI uses data on the traffic volume, the number of lanes, the speed limit, the presence of a bike lane, the presence of parking, and the presence of traffic control to give a rating for an intersection approach according to a six-point scale. Using the Bike ISI, practitioners have the ability to evaluate each approach at all intersections in their jurisdictions or at a select group of intersections. Once safety index values are assigned to each site, the practitioner can then select the sites with the highest index values and conduct more detailed reviews of those sites to determine whether any treatments are needed to improve the safety of the intersection.