Long-run equilibrium and short-run dynamics between risk exposure and highway safety

Based upon monthly California data, this exploratory analysis uses vector error correction methods and associated statistical tests to identify the long-run relationship and the short-run dynamics between highway exposure and crashes. The analysis finds that there is a cointegrating relationship between exposure and crashes, and for fatal, serious injury, and materials crashes, could not reject the hypothesis that crash exposure and frequency move proportionately. The analysis indicates that vector error correction models may be an important tool for improving our understanding of highway crashes and the near and longer term impacts of alternative safety policies.