For a two-year period large truck crashes on the interstate system in Washington State were investigated using a case-control method. For each large truck involved in a crash, three trucks were randomly selected for inspection from the traffic stream at the same time and place as the crash but one week later. The effects of truck and driver characteristics on crashes were assessed by comparing their relative frequency among the crash-involved and comparison sample trucks. Truck configuration, truck equipment condition, and driving hours were the dominant factors associated with increased crash risk. Double trailer trucks were consistently overinvolved in crashes by a factor of three regardless of driver age, hours of driving, cargo weight, or type of fleet. Driving in excess of eight hours increased the risk of crash involvement by a factor of two; drivers with logbook violations, young drivers, and interstate drivers also had increased crash risks. Trucks with defective equipment were overinvolved incrashes. Trucks with brake defects had a crash risk one and one-half times that for truck without brake defects. Trucks with steering defects had a risk that was at least twice that of trucks without defects.
Abstract