The Benefits of Using Connected Vehicles System on Traffic Delay and Safety at Urban Signalized Intersections

Connected and autonomous vehicles (CAVs) systems have the potential to reduce accidents, improve mobility for the disabled and elderly, increase road capacity, save fuel, and reduce pollution in the transportation system. Congestion is a common problem on every road network, particularly in intersections. With the inevitable deployment of CAVs, it is necessary to explore how they can operate at junctions in terms of traffic operation and safety. The study's primary objective is to determine the impact of CAVs on intersection traffic operations and safety. A 4-legged signalized intersection simulation case study with 5 various penetration rates of CAV scenarios (0 percent, 25 percent, 50 percent, 75 percent, and 100 percent of CAVs) was carried out using VISSIM microscopic traffic simulation to examine the impact of CAV on traffic performance. The safety impact of the different scenarios was evaluated using the Surrogate Safety Assessment Model (SSAM). The results showed that CAVs could significantly improve traffic movement with the increase of penetration rates, even when traveling with shorter headways, to improve road capacity and reduce delay and travel time. The delay reduction was from 4 percent to 10 percent, with the penetration rates between 25 percent and 100 percent. At the same time, the travel time reduction was between 3 percent and 8 percent, with the penetration rates between 25 percent and 100 percent. Moreover, the results showed that CAVs could improve safety significantly by reducing 35 percent of accidents. As for the delay cost, CAVs can reduce the delay cost by at least 3.25 million U.S Dollars per year by each 4-legged signalized intersection when the intersection is fully functioned with CAVs.