Severity analysis of single-vehicle left and right run-off-road crashes using a random parameter ordered logit model

ObjectivesSingle vehicle (SV) run-off-road crashes are a major cause of severe injury and fatality. Such crashes can result in different levels of severity depending on the direction (i.e., left or right) in which the vehicle runs off the road. This paper investigated the factors contributing to the crash severities of right run-off-road (R-ROR) and left run-off-road (L-ROR) SV crashes.MethodsThe study used SV crash data from the City of Charlotte, North Carolina, covering 2014 to 2017. Two separate random parameter ordered logit (RPOL) models were developed to estimate the contributing factors to R-ROR and L-ROR SV crash severities. The impact of the explanatory variables on the crash severity outcomes was quantified using the models' direct pseudo-elasticities.ResultsThe model results showed that male drivers, Driving Under Influence (DUI), motorcycles, and dry road surfaces were significant contributing factors to R-ROR and L-ROR SV crash severities. Specifically for the R-ROR model, speeding, reckless driving, 1-2 lanes, and older drivers increased crash severity. For the L-ROR model, phone distraction, crossed centerline/median, 3-4 lanes, rain, and dark unlighted roadway increased crash severity.ConclusionsBased on the estimated parameters for the common significant variables in the two models, it was inferred that L-ROR SV crashes are more likely to result in severe crashes compared to R-ROR SV crashes. Hence, this study contributes to the literature on ROR SV crashes by providing additional insight into contextual factors influencing ROR crash severity for more effective countermeasures.

Automated summary

This study investigated the factors contributing to the severity of single vehicle run-off-road crashes in terms of right run-off-road (R-ROR) and left run-off-road (L-ROR) crashes. The results showed that male drivers, Driving Under Influence (DUI), motorcycles, and dry road surfaces were significant contributing factors to both R-ROR and L-ROR crash severities. Speeding, reckless driving, 1-2 lanes, and older drivers increased the severity of R-ROR crashes, while phone distraction, crossed centerline/median, 3-4 lanes, rain, and dark unlighted roadway increased the severity of L-ROR crashes.