Priority metering control for an urban circular intersection

Nevertheless, all three types of circular intersections face capacity problems during periods of high traffic volume, resulting in long queues and delays. Signal metering was introduced to reduce long queues and delays on the dominant approaches to circular intersections by stopping the flow of traffic from other approaches. This methodology was found to ease congestion for circular intersections with historically high traffic volumes. However, most signal metering at those intersections employ fixed signal timing, in which the metering rate is not responsive to changes in traffic condition. This study investigates the performance of an adaptive metering system for circular intersections. The system was implemented on a real traffic circle having high and unbalanced volumes. The model was calibrated, and a case study was simulated for peak-hour traffic conditions. Using the PTV VISSIM application programming interface, the algorithm was tested and the performance of the system was compared to the current intersection operation. The results showed that adaptive metering can significantly reduce delays and queues at a traffic circle. This preliminary study can be a useful reference for the development of priority- controlled circular intersections.