Project Summary
Accidents are the largest source of external costs related to transportation with an estimated annual cost that exceeds $200 billion in the United States alone. Accidents lead to traffic backups that can result in secondary accidents. The purpose of this project is to investigate empirically whether the implementation of Changeable Message Signs (CMS), which belong to Intelligent Transportation System tools, can reduce secondary collisions by providing motorists with real-time traffic information. I will first review previously published methods of estimating secondary accidents to clarify the definition of secondary accidents and offer improvements. I will then study a 74-mile portion of Interstate 5 from the Mexico-US border to Orange County, CA that has 12 CMS, 3 of which are in southbound direction. This freeway has 4 to 6 lanes in each direction, and a maximum AADT volume of 230,000 vehicles. For this study area, I put together a unique dataset that includes accident data for year 2008 combined with detailed weather data. I will rely on counting and regression models to estimate the number of secondary incidents based on the number of primary accidents, weather conditions, time of day, traffic conditions and the availability of information.
