Commercial Driver Factors in Run-off-Road Crashes

Abstract

The number of commercial vehicles on U.S. roads has grown dramatically over the past few decades. Although the number of large trucks involved in fatal and injury crashes has decreased over the past 20 years, large trucks still have a higher fatal crash involvement rate than passenger cars do. This study sought to gain insights on the impact of commercial driver factors on crash severity with respect to single-vehicle, run-off-road (ROR) crashes. A logistic model was conducted with large truck crash data from the Washington State Department of Transportation (years 2006 to 2009). The model predicted the effects of truck driver distraction, inattention, speeding, seat belt usage, and drowsiness and fatigue on the likelihood of an ROR crash involving injury or fatality. Other factors, such as environmental conditions, roadway types, and truck-related factors, were controlled in the model. Results indicated that speeding, drowsiness and fatigue, and distraction and inattention strongly affected increasing crash severity. As expected, seat belt use significantly decreased the severity of an ROR crash. The study confirms that several driver factors observed in other studies on crash likelihood are also significant for ROR crashes involving large trucks.