Motor Carrier Safety: Crash Patterns of Inspected Commercial Vehicles

A linked database comprising state and federal roadside inspection, crash, and firm records of commercial motor vehicles is described. This combined database links information on vehicles inspected in the state of Illinois to the crashes that these vehicles may have been involved in anywhere within the United States. Two issues are addressed: determination of the components of an inspection-violation detection rate and the relationship between inspections and crashes. The first issue involves an attempt to quantify the components of a violation detection rate. For the second issue, four separate research questions are posed. The results of the second component indicate that there is no evidence that a significant difference exists in the expected number of crashes in which vehicles incurring zero violations were involved compared with the expected number in which vehicles incurring one or more violations were involved. About 2 percent of all inspected vehicles, which incurred zero violations, were subsequently involved in crashes. With every increase in the number of violations, the percent of vehicles involved in crashes increases by about 0.04. Further, a smaller percentage of vehicles that incur zero violations in Level I inspections are subsequently involved in crashes, compared with vehicles incurring zero violations under all Level II and Level V inspections. Moreover, the rate of increase in the percent involvement in crashes is greatest for vehicles incurring a positive number of violations in Level I inspections compared with vehicles subject to other types of inspection.