1371399 - An Anatomy of Crashes Involving Physically Impaired Drivers in Alabama: A Random Parameter Modeling Approach

People with physical impairment are one of the most vulnerable road users. Physically impaired drivers face many driving challenges and are prone to crashes. However, not many studies have been carried out to understand the factors that contribute to crashes involving these drivers and how these factors influence their crash outcomes. This study contributes in this regard to literature by exploring the factors influencing the severity of crashes involving drivers with physical impairment. The study used historical crash data from the State of Alabama and adopted random parameters with heterogeneity in mean modeling approach to account for unobserved heterogeneity in the data. Three crash outcomes, severe injury, minor injury, and property damage only (PDO), were considered in this study. The model estimation results revealed that rural areas, driving over the speed limit, time of crash between 6.00 pm-11.59 pm, younger drivers, employed and distracted drivers are associated with the occurrence of severe crashes. Minor injury crashes were found to be associated with female drivers, state roads, and residential land uses. Finally, PDO crashes were more associated with weekdays, driving under the influence of alcohol or drugs, a road with left curvature, driving too fast for the road condition, and intersections. The results obtained provide a foundation for the adoption of the safe systems principles to improve highway safety for physically impaired drivers. Ultimately, the findings of this study are expected to stimulate discussions among road safety professionals in developing appropriate and targeted countermeasures that may be implemented to improve the driving safety of people living with disabilities.