Modelling Performance Parameters of Roundabouts Using Gap Acceptance Method for Indian Traffic Scenario

Abstract

Road network connecting the various parts of the country defines the economy of the nation. This lead to vast development of road infrastructure. Intersections form a major unit of the road network. It is of utmost importance to design these intersections safely as they are the areas where maximum conflict points exist, which could otherwise lead to fatal. One such implication can be introducing roundabouts at intersections, which reduces the conflict points, thus providing greater safety and efficient traffic flow. The drivers’ behavior is one of the prime factors which influence the performance of these roundabouts. No such procedure of analysis is available in Indian context to identify the performance of roundabouts. To develop such a model, initially, the parameter defining driver behavior, i.e. Gap acceptance parameters had been estimated for heterogeneity in traffic. For this purpose, data was collected from 10 sites from different regions of India, giving priority to variations in traffic and driver behavior. The critical headway was then determined using three methods, namely, Raff, Ning Wu and Maximum Likelihood, for determining the appropriate one for the model. These parameters were then utilized in deriving an equation for entry capacity in Indian context. The equation obtained satisfied the sites with high circulating flow. When compared with other existing gap acceptance models, the German model mostly over predicted the capacity as compared to developed model, while the HCM model underestimated the same.