Evaluation of Illinois Crash Data Reported to MCMIS Crash File

This document is part of a series of reports 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. Earlier studies showed that reporting to the MCMIS Crash file was significantly incomplete in other states. This report evaluates reporting to the MCMIS Crash file from the state of Illinois. MCMIS Crash file records were matched to the Illinois Police Accident Report (PAR) file to determine the nature and extent of reporting. Overall, Illinois submitted 43.0% of its reportable crash involvements to the MCMIS Crash file in 2003. Reporting rates varied by vehicle type, crash severity, and reporting agency. Reporting rates are 71.0% for fatal crashes, 42.3% for injury cases, and 42.6% for tow/disabled accidents. Single unit trucks are reported only 25.6% of the time, while tractor semitrailers and tractors without trailers each have reporting rates over 52%. Buses are only reported 4.3% of the time. The state police reported 61.8% of cases they covered compared with 32.7% for the local police. The Chicago area accounts for a large proportion of the unreported cases. Although Illinois' data collection system is comprehensive, it appears that issues connected with identifying the vehicle as a commercial vehicle (CV) is preventing all MCMIS-eligible vehicles from being identified. Officers are less likely to recognize smaller vehicles as CVs, and thus do not record those variables for these cases. Evidence suggests that failure to fill out the CV section of the PAR form results in such cases not being submitted to the MCMIS Crash file.