Denis Monyo, Dr. Thobias Sando
Dr. Thobias Sando | College of Computing, Engineering and Construction | School of Engineering
Secondary crashes (SCs) on freeways are one of the major causes of non-recurrent delays. Even though they are generally fewer than normal crashes, their impact can be far-reaching and long-lasting than normal crashes. SCs can result in deterioration of traffic flow conditions on freeways and adjacent arterials in addition to injuries and fatalities. Due to the limited nature of secondary crash data for scenarios that may not yet exist, such as operations under the connected vehicles (CV) environment, surrogate measures provide means to examine expected safety characteristics of such deployments. This study evaluated a freeway model of a segment on Florida’s Turnpike system using VISSIM – a microscopic simulation software. Trajectory files generated in VISSIM were imported in the SSAM software for conflict analysis to analyze the potential benefits of CVs in mitigating SCs. The study identified that the location of the primary incident, whether on the inside or outside lane, influences the number of conflicts generated by SCs. A primary incident on the outside lane resulted in more conflicts than the one on the inside lane. This is due to additional conflicts of on-ramp and off-ramp traffic. In both cases, the results showed a potential reduction of SCs with traffic conflicts of up to 90% at high CV market penetration. Notably, the statistical analysis showed that the average time-to-collision was significantly different, even at lower CV market penetration. In the case of primary incidents that resulted in multiple lanes blockage, the results indicate the necessity of diverting traffic to parallel arterials to improve safety benefits of CVs.