Evaluation of 2006 South Carolina 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 South Carolina. MCMIS Crash File records were matched to the South Carolina PAR file to determine the nature and extent of underreporting. The vehicle type variable in the PAR file has only two levels for identifying medium/heavy trucks: truck tractors, and other trucks. Overall, it appears that South Carolina is reporting 77.9 percent of crash involvements that should be reported to the MCMIS Crash file. The reporting rate for truck tractors is 84.7 percent, while the reporting rate for other trucks is 64.5 percent. Fatal crashes are reported at about 90 percent, but injured/transported and towed/disabled crashes are reported at about 79 and 76 percent, respectively. With respect to timing issues, there is a declining trend in reporting rates towards the end of the calendar year. The reporting rate in December is 62.7 percent. The Highway Patrol has a reporting rate of 85.2 percent, while the reporting rate for police departments is 57.6 percent and for sheriff’s offices is 60.6 percent. Missing data percentages in the MCMIS Crash file are generally low, with a few exceptions. Because the South Carolina PAR file has only two categories for medium/heavy trucks, the vehicle configuration variable does not match well between the PAR file and the MCMIS file.