Simulated Capacity of Roundabouts and Impact of Roundabout Within a Progressed Signalized Road

Many intersections in the urban areas are signalized. As roundabouts are beginning to multiply, they are being considered adjacent to signalized intersections and for replacing some signalized intersections. Traffic simulation has been used to study the performance of both signalized and un-signalized intersections. This research uses simulation to study the traffic impacts of roundabouts. In this paper, two problems are studied. Firstly, urban single lane and dual lane roundabouts are modeled in VISSIM traffic simulation software. Simulation results are compared with the results of RODEL (empirical model) and aaSIDRA (analytical model). Comparison with real data collected from various sites in United States shows that VISSIM results are closer to the real data than the RODEL and aaSIDRA results. Secondly, the impact of signalized intersection proximity to roundabouts is studied using the developed model. More specifically, the impact of coordinated signalized arterial when a roundabout is inserted within an arterial corridor is studied. Results of average delay measures are comparable to the signalization alternative when the roundabout is operating below capacity. However, at heavy volumes, when the roundabout is operating at capacity, then the performance of signalization is slightly better.