Comprehensive Injury Severity Analysis Of Suv And Pickup Truck Rollover Crashes Alabama Case Study

The research described in this paper explored the factors contributing to injury severity resulting from rollover accidents of light trucks-SUVs and pickups in particular-in Alabama. Given the occurrence of a rollover crash, random parameter logit models of injury severity (with possible outcomes of fatal, major, minor, and possible or no injury) were estimated. The estimated models identified a variety of statistically significant factors influencing the injury severities resulting from SUV and pickup rollover crashes. According to these models, some variables were significant in one model (SUV or pickup) but not the other. For example, variables such as roadway downgrade, female drivers, and daylight were significant only in the SUV model. Variables such as driver fatigue, driver or occupant wearing a seat belt, and freeway were significant only in the pickup model. In addition, some variables (such as not wearing a seat belt, two-lane roadway, horizontal curve, and old driver) were significant in both models. Estimation findings showed that two parameters (horizontal curve and at intersections) in the SUV model and two parameters (horizontal curve and dry roadway surface) in the pickup model could be modeled as random parameters, indicating their varying influence on the injury severity related to unobserved effects. The results obtained are used in this paper for a discussion of the effects of variables on pedestrian and bicyclist injury severities and their possible explanations.