ROUNDABOUT INTERSECTIONS: ANALYSIS FOR SCENARIOS BY MICRO-SIMULATION

In the literature, many analytical techniques allow the study of the performances (Capacity, Levels Of Service, etc) of roundabout intersections: probabilistic methods (HCM, HBS etc.), statistic methods (TRRL, SETRA) etc.. Each method, when formulated, has to consider some aspects of roundabout circulation in comparison to others (geometric elements, vehicular flow and consumer behaviour). Often, recorded results are not comparable among themselves if all the analytical methods used in the same case study are applied. An approach that allows a global vision of the problem is today represented by the use of refined simulation analysis software of vehicular circulation. In this paper the authors introduce the first results of a large survey conducted on an ample range of roundabout scenarios through the application of a modern simulation software. Each scenario describes a fixed roundabout phenomenon using the following variables: - geometric elements (Inscribed circle radius, Circulatory roadway, Central and Splitter Islands etc.); - characteristics of the traffic flow (Density, Distribution, Crossing and approach speeds etc.); The results are presented in terms of level of service offered.