A modern injury risk curve for pedestrian injury in the United States: the combined effects of impact speed and vehicle front-end height

Monfort, Samuel S. / Mueller, Becky C.
Insurance Institute for Highway Safety
December 2024

Objective: Estimating the likelihood of pedestrian injuries at different impact speeds is important for research and regulatory efforts related to infrastructure and vehicle design. However, a risk curve is only valuable if it is based on crash data that accurately represent the current vehicle fleet. This study, therefore, aimed to provide an updated estimate of pedestrian injury risk at different severity levels using recent crash data from U.S. roads.
Method: We analyzed 202 pedestrian crashes to generate an estimate for the link between injury outcomes and impact speed. Measurements of the vehicles involved were used to examine the moderating effect of hood leading edge height.
Results: We generated injury risk curves by impact speed at three different severity thresholds (MAIS 2+F, MAIS 3+F, and fatal). As expected, impact speed strongly predicted injury risk, and hood leading edge height significantly increased the risk of pedestrian injury overall as well as the potency of impact speed for serious injuries. Formulas are included to generate injury risk curves for pedestrians of different ages and sexes, and for vehicles of different hood leading edge heights.
Conclusions: Our risk curves for pedestrian injury risk are shifted leftward (i.e., with injury inflicted at lower impact speeds) compared with contemporary estimates of pedestrian injury risk in Europe. This difference is likely due to the prevalence of larger, taller vehicles in the United States.