Evaluation of 2006 Idaho crash data reported to the MCMIS crash file

Abstract

This report is part of a series evaluating the data reported to the Motor Carrier Management Information System (MCMIS) Crash File undertaken by the Center for National Truck and Bus Statistics at the University of Michigan Transportation Research Institute. The earlier studies showed that reporting to the MCMIS Crash File was incomplete. This report examines the factors that are associated with reporting rates for the state of Idaho. MCMIS Crash File records were matched to the Idaho Crash file to determine the nature and extent of underreporting. Overall, it appears that Idaho is reporting 72.9 percent of crash involvements that should be reported to the MCMIS Crash file. Reporting rates vary by crash severity and vehicle type. Overall, more than 90 percent of fatal and injured/transported involvements are reported, but the rate drops to 60.7 percent for crashes that are reportable based on the towed and disabled criterion. Furthermore, 86 percent of the unreported cases fall into the towed and disabled category. It appears that injury-related crashes tend to be reported, while those involving no injury are less likely to be reported. Crashes involving large trucks such as tractor-semitrailers or doubles combinations were more likely to be reported than crashes involving small, single-unit trucks or buses. The reporting rate for the state police is 82.0 percent, while the rate for police departments is 55.7 percent. Missing data rates, except for a few variables, are generally low in the MCMIS Crash file. Compatibility between the vehicle configuration and number of fatalities variables in the Idaho Data file and the MCMIS Crash file is generally good.