Summary

This research aims to reduce wet weather collisions by developing an improved model for identifying locations with excess risk of collisions during wet weather so that risk can be mitigated through enhanced highway design or other countermeasures. The potential for risk reduction is significant: in 2001, there were over 23,000 wet pavement collisions on the California state highway system. The cost of these collisions is estimated to be about $1,382,300,000. Even a modest reduction in such collisions would result in large savings and improved highway safety. The researchers will conduct an empirical investigation to evaluate risk as a function of rain intensity and highway design. This will be done in two phases. Phase I will focus on just two highway sites. In this phase, various data gathering methods will be assessed. If Phase I is successful, a comprehensive proposal for more extensive data collection will occur in Phase II. Based on the findings, recommendations will be reported for evaluating and mitigating wet-weather risk. This new model of wet pavement and collision risk will give Caltrans a tool for evaluating wet weather risk as a function of different highway characteristics and for reducing such risks.