Estimating Critical Gap at Roundabout under Mixed Traffic Conditions in Sri Lanka

抄録

Capacity of a roundabout is highly dependent on gap acceptance parameters. One of the major influential parameters is critical gap. Many researchers have used various methods in estimating critical gap (tc) at different types of intersections including roundabouts. Much attention has been drawn into homogenous vehicle flow, but less attention has been drawn into heterogeneous traffic flow conditions related to local vehicle conditions based on its composition in Sri Lanka. Motorcycles and three-wheelers possess up to 50% of the vehicle mix in Sri Lanka. It is very important to analyze the impact for critical gap under this condition. In this paper, present methods for estimating critical gap are compared and new method for estimating critical gap is proposed incorporating the vehicular mix. Applicability of the proposed method and critical gap value for each vehicle category for local roundabout condition has been determined.