Municipal, state, and federal agencies in the U.S. responsible for traffic safety have used crash rates such as fatalities per 100 million vehicle-miles traveled (VMT) as a traffic safety performance of their governing areas. However, appropriateness of such rates being used as a performance measure has not been examined empirically although the rates have been publicly in use.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 of Virginia 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 are the most appropriate as long-term (1971-2006) and short-term (1995-2006) Virginia’s safety performance measures, respectively. Statistical uncertainty should be considered when these rates are used to measure a safety performance.
Abstract