OBJECTIVE: Mountainous highways usually exhibit complex geometry features such as steep gradients or sharp curves, which can cause considerably different driver behavior and vehicle performance as compared to non-mountainous ones. In addition, mountainous highways are more often to experience adverse weather conditions than non-mountainous counterparts. We examine different characteristics of crash injury severity from a mountainous (MT) highway and a non-mountainous (NM) highway.
METHODS: One major interstate highway with typical mountainous (MT) terrain and another one with non-mountainous (NM) terrain in Colorado have been selected for this study. A comparative investigation about the impact on injury severity from mountainous and non-mountainous highways is conducted. Separate mixed logit models are estimated for both highways with four-year detailed crash data.
RESULTS: Incorporating two major interstate highways from the same region into the comparative study offers some unique strength on investigating the impacts from different causes. As a result, the study provides better insights about contributing factors and associated mechanism for injury severity on mountainous highways. Substantial differences in the magnitude and direction of the influence of some contributing factors between MT and NM models are observed. Some new findings about injury severity on mountainous highways are made possible for the first time.
CONCLUSION: The findings in this study provide scientific guidance to potentially improve the current highway design and traffic management policy on thousands of miles of mountainous highways in the country.