Examination of Macrolevel Annual Safety Performance Measures for Virginia

Municipal, state, and federal agencies in the United States that are responsible for traffic safety have used crash rates such as fatalities per 100 million vehicle miles traveled (VMT) as traffic safety performance measures. However, the appropriateness of using such rates as performance measures has not been examined empirically, although the rates have been made public. This study examined 20 candidate crash rates (e.g., fatalities per million population and injury crashes per million registered vehicles) for an annual safety performance measure for Virginia by using autoregressive error models and empirical data from 1971 through 2006. The study found that the injury rate per driver and the crash rate per VMT seem appropriate as, respectively, long-term (1971 to 2006) and shorter-term (1995 to 2006) safety performance measures for Virginia. Statistical uncertainty should be considered when these rates are used to measure safety performance.