Congestion Management at Roundabouts – A Case Study

In Australia roundabouts are prevalent in controlling many minor and some major intersections. Often the capacity of existing roundabouts at major intersections is tested at peak times and traffic delays on one or more approaches can become unacceptable. One tested method of providing an additional level of control is to signalise one or more of the approaches to the roundabout. A case study of an existing roundabout is presented to demonstrate the situation without partial signal control compared to the situation with partial signal control. Intersection operation is simulated by using SIDRA INTERSECTION software and the theoretical results compared to actual results in the field. This case study presents not only information on major intersection control by roundabouts but also how congestion at peak times can be managed by the introduction of traffic signal control on one or more approaches. It also provides practical information on how roundabouts can be simulated using SIDRA INTERSECTION software.