Evaluation of transit signal priority in RBC and ASC/3 software-in-the-loop simulation environment

In recent years, traffic simulation software packages have become powerful tools in developing and studying the impacts of different traffic scenarios. This study presents a use of the VISSIM traffic simulation software in evaluating Transit Signal Priority (TSP) strategies using two types of emulated signal controllers: the Ring Barrier Controller (RBC) emulator, and the ASC/3 Software-in-the-Loop (SIL) traffic controller. The two signal control types were evaluated and compared for their abilities to provide TSP and the impacts it causes on the overall traffic. The results have shown benefits of the evaluated traffic controllers within VISSIM in simulating different TSP strategies, despite some differences and problems with controller settings. On the test-case network, the results have shown reductions in transit travel times from 4 to 7%, which are assigned to TSP. With combined Bus Rapid Transit (BRT) and TSP strategies, these travel time savings were in a range from 15 to 20%. Impacts on general purpose traffic along the main corridor were not observed, while TSP causes an increase in delays on side streets of approximately 1% and an increase in the number of stops of approximately 0.5%. The results also showed some differences in the way the two controller types implement TSP strategies.