Pedestrian and Bicycle Intersection Safety Indices completed by HSRC

The U.S. Department of Transportation Federal Highway Administration, through research conducted at the UNC Highway Safety Research Center, recently completed the development of the Pedestrian and Bicycle Intersection Safety Indices. These indices are a set of models that enable users to identify intersection crossings and intersection approach legs that should be the greatest priority for undergoing in-depth pedestrian and bicycle safety assessment. Using observable characteristics of an intersection crossing or approach leg, such as number of lanes, area type, presence of bike lane, type of traffic control, and traffic volume, the tool produces a safety index score. Higher scores indicate greater priority for an in-depth safety assessment.

Each leg of an intersection may have different characteristics affecting pedestrian or bicyclist safety. Therefore the tool is intended to provide a rating of the safety of an individual crossing (Ped ISI) or approach leg (Bike ISI) rather than evaluating the intersection as a whole. A practitioner can use the tool to develop a prioritization scheme for a group of pedestrian crossings or bicyclist approaches. This method enables the practitioner to prioritize and proactively address sites that are the most likely to be a safety concern for pedestrians or bicyclists rather than having to wait for analysis following a crash or cluster of crashes at an intersection.

Researchers developed the Ped ISI and Bike ISI tools based on both safety ratings and observed behaviors. The ratings were derived from expert opinions of safety of each site. Behaviors were acquired through observations of interactions between pedestrians or bicyclists and motorists. These measures enabled the researchers to use a multifaceted approach to determine the relative safety of a crossing location for pedestrians or an approach leg for bicyclists.

To develop the Ped ISI and Bike ISI models, researchers studied 68 pedestrian crossings at signalized and unsignalized intersections in Miami, FL, Philadelphia, PA, and San Jose, CA, and 67 bicyclist approaches at signalized and unsignalized intersections in Eugene, OR, Gainesville, FL, Philadelphia, PA, and Portland, OR.

To find out more about the Pedestrian and Bicycle Intersection Safety Indices, please visit: www.tfhrc.gov/safety/pedbike/pubs/06125/.