Primary pedestrian crash scenarios: factors relevant to the design of pedestrian detection systems

April 2011

Objectives: Vehicle manufacturers are implementing advanced technologies aimed at reducing the severity of pedestrian crashes or avoiding them altogether. The objective of the current study was to determine the most common and injurious pedestrian crash scenarios in the United States to help set priorities for the design of pedestrian detection systems. The study focused on single-vehicle crashes in which pedestrians were struck by the fronts of passenger vehicles. Methods: Crash records were extracted from the 2005-09 files of the National Automotive Sampling System General Estimates System (NASS GES) and the Fatality Analysis Reporting System (FARS). Crash descriptors such as vehicle movement, pedestrian movement, and driver view obstruction were reviewed to develop a typology of crash scenarios. Crashes then were classified into various scenarios, and the most common scenarios were identified. Results: The largest number of pedestrian crash involvements and deaths involved a pedestrian crossing the roadway while the vehicle was traveling straight. This scenario accounted for 43 percent of pedestrian involvements and 46 percent of pedestrian deaths in single-vehicle crashes. The other main crash scenarios involved the pedestrian traveling in-line with traffic while the vehicle was traveling straight and the pedestrian crossing while the vehicle was turning. A larger proportion of fatal pedestrian crashes occurred in nondaylight conditions and on roadways with speed limits higher than 40 mi/h, when compared with pedestrian crash involvements of all severities. Conclusions: Vehicle technologies that can quickly and accurately detect pedestrians in the three most common crash scenarios potentially can mitigate as many as 65 percent of pedestrian involvements and 58 percent of pedestrian deaths in single-vehicle crashes in the United States. There is great potential for pedestrian detection systems, but they must function in low-light conditions and at higher vehicle speeds to address a large proportion of pedestrian deaths.