Evaluating ITS strategies for real-time freeway safety improvement

Traffic crashes on urban freeways account for thousands of lives lost and billions of dollars wasted every year in America. Previous research has shown that certain freeway conditions are more susceptible to crashes occurring than others. These conditions are said to have a high crash potential. The purpose of this research is to test the effects of intelligent transportation system (ITS) strategies on reducing the potential for crashes to occur on a major urban freeway. In this research, Interstate-4 in Orlando, Florida was simulated using the PARAMICS micro-simulation software package. The crash potential was then determined through models that were created in the previous research conducted by Abdel-Aty et al. (2005) using logistic regression to associate traffic characteristics with the risk of a crash occurring. Several mitigation strategies were used while simulating the freeway and the crash potential was determined for each technique. The before (pre-ITS) and after case were then compared to examine the effects of the crash mitigation methods. The results of this research show that variable speed limits (VSL) have a positive effect on lowering the crash potential during high-speed conditions. VSL does not affect the low-speed case but if ramp metering is instead implemented the potential for a significant reduction in the crash potential is realized. However, there are still more strategies that need to be tested including route diversion, lane change restrictions, and feedback controlled ramp metering