Investigating Crash Characteristics of Multiple-Lane Highways in Louisiana

There are about 1,520 miles of multiple-lane (excluding freeway) highways in Louisiana that amounts to 9% of all highways on the Louisiana Department of Transportation and Development (LaDOTD) roadway system. However close to 50% of total crashes and 22% of total fatal crashes occur on multiple-lane highways annually. Reducing number of crashes on multiple-lane highways is crucial for LaDOTD. This paper investigates characteristics of crashes on multiple-lane highways in Louisiana and identifies the top sites for safety improvements by the network screening methods introduced by the on-going Highway Safety Manual projects. Classifying the multiple-lane highways by median (divided and undivided) and area (urban and rural), the results show that urban undivided highway is the most dangerous highway with the highest overall crash rate, and rural divided highways is the most fatal highway with the highest fatality rate in Louisiana. Unlike other types of highways, collisions with other vehicles consist of more than 70% of all crashes. Rear-end crash is the most common type of collision on this type of highways. The results from network screening reveal the characteristics of top ranking sites by four different methods.