Capacity and Level of Service of Signalized Roundabouts in Urban Indian Context

Modern roundabouts, first installed in England in the early 1960s, are becoming popular substitutes for signalized intersections in India. These facilities were originally introduced in order to solve the problems of the existing rotaries and traffic circles. This thesis presents a formulation for evaluating the capacity, delay, and level of service of multilane signalized roundabouts. Based on the study of available literatures, the formulation uses the gap acceptance theory and evaluates entry lanes on a lane-by-lane basis. Besides circulating and exiting flows, number of lanes and lateral position of the vehicles, as they approach and cross the roundabout, showed significant influence on roundabout entry capacity. Substantial differences in capacity estimates were observed between various considered methods. It is quite essential to calibrate such methods to meet regional needs. This study describes a new model for capacity estimation and level of service analysis of signalized roundabouts derived under heavy demand conditions at large roundabouts. The capacity estimation models, FHWA, IRC & SIDRA shown that the selected roundabout are under saturation condition and the Level of Service (LOS) was found out to be satisfactory.