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Evaluation of Maryland crash data reported to MCMIS crash file


Authors: Paul E. Green, Anne Matteson

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 Maryland. MCMIS Crash file records were matched to the Maryland Police Accident Report (PAR) file to determine the nature and extent of reporting. Overall, Maryland submitted 31.1% of its reportable crash involvements to the MCMIS Crash File in 2004. Reporting rates varied by crash month, vehicle type, crash severity, and reporting agency. Reporting rates were unusually low in November, December, and January. Reporting rates are 84.6% for fatal crashes, 56.0% for injury cases, and 15.6% for tow/disabled accidents which account for 77.3% of unreported cases. Thus, the reporting rate is mostly influenced by low reporting of reportable tow/disabled cases. Single trucks with 2 axles are reported 26.4% of the time, and school buses are reported 23.5% of the time. The state police reported 39.2% of cases they covered compared with 24.8% for the local police. The Baltimore City local police reported only 2% of reportable cases, and in addition had the largest percentage of unreported cases among local police agencies (18.5%). Data quality is also reviewed. The MCMIS file is examined for missing data rates and the Maryland PAR file is compared to the MCMIS Crash file with respect to vehicle type for reportable and matched cases.