Evaluation of Roundabout Performances Using a Micro-Simulation Software

The growing use of roundabout to solve traffic problems has given rise to a large number of models to predict the performances of a roundabout. Each of these ones allows estimation of several features, such as capacity, approach delays and queue lengths through probabilistic or statistical formulations. The restrictions of these models, as well as the difficulty of their use, especially during oversaturation conditions, have driven researchers to use software that can simulate roundabout users behavior. In this regard the Authors present an extensive campaign of research based on several scenarios of roundabout with the aid of VISSIM micro-simulation tool. So three separate sets of scenarios for single-lane roundabouts are composed and analyzed, in total, 288 scenarios, considering as variables both the geometric features (width of splitter island, external roundabout radius, width of circulatory roadway) and the characteristics of traffic flow (distribution and assignment) and the circulation rules (approach and circulatory speed, priority rules). The evaluation of approach delay for each scenario allows to show the results in terms of level of service offered according to HCM 2010.