Exploring run-overs in two-wheeler–motor vehicle crashes: Injury severity, mediating effects, and implications for prevention

Concerns regarding the injuries and fatalities of two-wheeler riders are rising in China, particularly when the riders are run over by motor vehicles. This article aims to: (1) examine the impact of being run over on the severity of injuries sustained by two-wheeler riders, and to ascertain whether run-overs act as mediators in the relationship between injury severity and other contributing factors, and (2) identify the main causes leading to run-over crashes. 2,281 two-wheeler–motor vehicle crashes were collected from the China In-Depth Accident Study Database from 2017 to 2020. Random-parameter binary logit model and random-parameter ordered logit model were used to investigate factors influencing run-overs and injury severity. Based on the marginal effects of the two models, path analysis was conducted to quantify the direct and indirect relationships between the contributing factors and both run-overs and the severity of injuries sustained. Model results reveal that being run over is a predominant factor exacerbating the severity of injuries among two-wheeler riders. Furthermore, the occurrence of run-overs is significantly correlated with riders’ age, crash location, two-wheeler length, and the presence of work zones. Additionally, the influence of certain factors on injury severity is mediated through the occurrence of run-overs, with both partial and full mediation effects observed. For example, the impacts of riders’ age and two-wheeler’s primary crash position on injury severity are partially mediated by run-overs. This indicates that both the age of riders and the primary crash position contribute to severe injuries, operating through direct effects as well as in the context of run-overs. Findings of this study highlight the mediating role of run-overs in the injury severity of two-wheeler riders. Practically, the findings provide insights for roadway design and installation of proactive equipment aimed at mitigating the risk of run-overs and the associated severe injuries.