Paper Details

TRB 91st Annual Meeting (January 22-26, 2012)

Event Number:	652
Event Title:	Pedestrian Safety and Operations
Event Date:	Jan 24 2012 7:30PM- 9:30PM
Event Location:	Marriott, Salon 2
Event Description:
Event Agenda:

Using Event-Based Data to Assess Vehicle Pedestrian Crash Risk in the Absence of Clearance Interval at Signalized Intersections (12-2159)

All-red clearance interval plays a pivotal role in preventing potential vehicle pedestrian conflicts at signalized intersections. A recent study suggested that retiming of clearance interval resulted in a 37% relative reduction in pedestrian and bicycle crashes. Since these modifications generally led to increases in the clearance intervals, results from the study have implications regarding the mechanism by which at least some vehicle-pedestrian collisions occur. To validate such findings, a simulation based method using high-resolution event-based data obtained from loop detectors at three signalized intersections was used to first estimate crash probabilities and then a counterfactual approach to calculate the probability of the absence of the all-red phase as a necessary condition for the occurrence of the crash provided an alternate estimate of crash reduction factor for the all-red phase. Our study suggested that intervention of clearance interval was able to prevent 100% of potential crashes, which would have occurred otherwise even with driver’s emergency braking effort. Such deviation in findings from the previous report could be attributed to the fundamental difference between the nature of the vehicle pedestrian conflicts at the two studies.

Authors
     Chatterjee, Indrajit , University of Minnesota, Twin Cities
     Davis, Gary A., University of Minnesota, Twin Cities