A Proposal of Two Signals Roundabout Analysis Method Using SIDRA6

Roundabouts face a congestion problem when there are unbalanced traffic conditions, especially during peak times. The congestion at roundabouts results in long delay times and low level of service. Some research has addressed congestion problems of the metering roundabout, however, few studies have focused on the congestion issues of the double signals metering roundabout. This research bridges this gap through analyzing the congestion issues of the Old Belair double signals roundabout in Adelaide. The research proposes a new analysis method based on a four-nodes intersection in order for double signals roundabout analysis to be carried out as follows: firstly, at the modeling stage, a connection of four individual intersections, adjustment of lane geometry, input of directional traffic volumes, priority and phase time set up are proposed. Secondly, for calibration, PFF, critical gap, follow-up headway and extra bunching values have been applied. The results from the analysis show that the new method is able to analyze the delay time, level of service, degree of saturation and allow for further analysis.