Investigation of characteristics and assessment of crash severity factors associated with truck-related crashes in Ohio

Truck safety is a very crucial aspect of the overall safety of the transportation system. Statewide there has been a significant increase in the probability of trucks being involved in crashes, primarily due to the fact that the total number of registered trucks, as well as the truck vehicle-miles traveled, have both increased within the last 10 years. Recognizing the substantial impact of truck-related crashes in the overall transportation safety, this study attempted to identify the contributing factors that influence the increase in truck-related crash severity, using truck-related crash data for the last two and half years (July 2013-December 2015) that were obtained from the Ohio Department of Public Safety Traffic (ODPS). This thesis study used the classification tree model to investigate the important factors affecting injury and fatality related to truck crashes in Ohio. Eighteen independent variables that represent various driver, roadway, environmental and crash characteristics were tested in the classification tree model of truck-related crash model. The dependent variable, crash severity was coded as a binary variable, with no injury and injury/fatal as its two crash severity levels. The classification tree model selected five independent variables as the only most significant factors influencing truck-related crash severity. These variables are crash type, posted speed limit, collision event, speed-related and road contour. Their significance is also in that order, with the crash type being the most significant, contributing about 55.8% to the model, posted speed limit contributing about 18.5%, collision event about 17.7%, speed-related about 6.0% and lastly road contour about 2.0