Comparing Roundabouts and Signalized Intersections Through Multiple- Model Simulation

In modern transportation systems, more and more vehicles result in severe traffic congestion, affecting our daily life and modern logistics. Well-designed traffic infrastructures play an important role in implementing safe and efficient traffic systems. From subjective experience, roundabouts are more efficient than conventional signalized intersections because vehicles do not wait for traffic signals, decreasing which is the main reason for time-loss at signalized crossroads. This paper aims to further investigate the differences between intersections and roundabouts in the capacity of vehicle passing and other performance. Two scenarios with different traffic volumes are considered, including a large volume of traffic flow (2.44 vehicles per second) and a small volume of traffic flow (0.52 vehicles per second). In each scenario, we build six junction models including four intersections with different traffic light time and two roundabouts with different numbers of lanes. Multiple evaluation metrics (i.e., number of passing vehicles over time, mean speed of passing vehicles, mean number of halts per vehicle, mean time-loss per vehicle, and total time for all vehicles to pass) are considered to compare these models' performance. Results illustrate that roundabouts have a higher capability of vehicle passing than intersections, especially for a large traffic volume. But roundabouts bring more halts per vehicle than signalized intersections when the traffic volume is large. When the volume of traffic flow is small, there is no significant efficiency difference between intersections and roundabouts. These results tend to be applied to future traffic junction designs to improve system efficiency.