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Revised ratio of crash severities reportable to the MCMIS crash file


Authors: Paul E. Green, Daniel Blower

The Motor Carrier Management Information System (MCMIS) Crash file has been developed by the Federal Motor Carrier Safety Administration (FMCSA) to serve as a census file of trucks and buses involved in traffic crashes meeting a specific crash severity threshold. Each state is responsible for identifying cases that meet the MCMIS Crash file criteria and reporting the required data through the SafetyNet system. UMTRI has completed a set of evaluations of state reporting and found that reporting rates range from over 80 percent to less than 10. The present report provides a method of predicting, given a known number of fatal involvements, the number of crash involvements a state should be reporting. In each state, the number of fatal involvements is well-known, so all states will start with a known quantity, the number of fatal truck and bus crash involvements. It is then hypothesized that the ratio of reportable crash severities, that is, the ratio of fatal involvements to nonfatal involvements, will apply across all the states.Data from eight states that provide all the information necessary to identify MCMIS-reportable cases were used. A weighted log-linear model is fit to MCMIS data for the eight states that have information recorded for both fatal and nonfatal crashes. The model is then used to estimate the number of nonfatal crashes for a new state in which only the number of fatal crashes is known. Prediction intervals are presented.

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