Examination of Fault, Unsafe Driving Acts, and Total Harm in Car-Truck Collisions

Crashes involving large trucks and passenger cars are important topics for research and countermeasure development since they represent more than 60% of all fatal truck crashes and because the passenger car occupant is much more likely to be killed. This study (a) examined “fault” in total car–truck crashes using North Carolina Highway Safety Information System (HSIS) data for comparison with fault analyzed in previous studies of fatal crashes, (b) used general estimates system (GES) crash data to verify unsafe driving acts (UDAs) identified by expert panels in past studies, and (c) used North Carolina HSIS data to identify critical combinations of roadway facility type, roadway location, and crash type based on “total harm”—a measure combining both the frequency and severity of the crash. Fault in total North Carolina car–truck crashes was found to differ significantly from past fatal crash studies, with the truck driver being at fault more often than the car driver both overall and in certain crash types. Car drivers continue to be at fault much more often in head-on and angle crashes. While it was not possible to analyze all UDAs identified in prior studies, when possible, the current analyses revealed differences between the GES crash data results and the expert-based results, pointing to the need for better UDA methods if they are to be used to target treatments. Finally, using the total-harm analysis with North Carolina car–truck crashes indicated that undivided rural arterials and collectors should be primary targets for further investigation and for treatment.