The evolving vehicle fleet and pedestrian harm: Heterogeneity based data-driven analysis

This study disaggregates pedestrian injury severity outcomes by both vehicle type and vehicle generation to statistically examine how pedestrian risk has evolved in the modern U.S. vehicle fleet. Using nationally representative Crash Report Sampling System data from 2021 to 2023, random-parameter logit models with heterogeneity in means are estimated separately for passenger cars and light trucks (which includes SUVs, and pick-up trucks) across three model-year cohorts: older vehicles manufactured between 2000 and 2010, transitional vehicles produced between 2011 and 2015, and modern vehicles produced in 2016 or later. This disaggregation reflects major shifts in vehicle mass, geometry, and the diffusion of pedestrian-related safety technologies over the past two decades. The results reveal substantial generational instability in pedestrian injury-severity relationships, particularly for light-truck vehicles. Out-of-sample simulations show that, under identical crash circumstances, transitional and modern vehicles in both classes are associated with higher predicted probabilities of severe pedestrian injury compared to older vehicles. While light trucks exhibit higher severe-injury risk than passenger cars in older generations, this class-based gap narrows substantially in modern vehicles, indicating a convergence in pedestrian injury severity outcomes. These findings demonstrate that treating vehicle classes as static masks important generational effects and highlight the need to explicitly account for vehicle generation when evaluating pedestrian risk and developing safety countermeasures.