Gap Acceptance Behaviour of Vehicles at Unsignalized Intersection in Urban Area

Abstract

Gap acceptance is an important component in microscopic traffic characteristic, which is used in the determination of capacity and delay of the individual movements of vehicles at an uncontrolled intersection. This concept is based on defining the extent drivers will be able to utilize a gap of a particular duration. Most of the studies related to critical gap estimation have been carried out in developed countries where traffic is homogeneous and rules of priorities as well as lane disciplines are followed. However, in developing countries like India, where heterogeneous traffic condition exists, priority rules are less honoured which consequently creates conflicts on intersections. In this paper, an attempt is made to analyse gap acceptance behaviour of motorized two-wheelers (MTW) and cars as these are the dominating vehicles at the selected study location, which is an unsignalized T-intersection. Data was collected for six hours of duration by videography consisting of two hours of duration each for morning, afternoon and evening time. In the study, the straight going flow was considered as a major stream and the other as a minor stream. In this study, three different methodologies are used to determine critical gap assuming independence between the arrival time of minor stream vehicles and the ones of the major stream vehicles. The critical gap for minor to major manoeuvre was calculated for MTW and cars. It was observed that gap acceptance showed variation between various methods. Two methods show nearly the same time while other shows less time of gap acceptance. The gap acceptance of MTW is significantly less than the car, which indicates there is a considerable effect of size and manoeuvrability of vehicles on gap acceptance. Also, there is variation in morning and evening period gap acceptance behaviour; morning gap acceptance is significantly more than evening time, which may be due urgency of vehicle users to reach their destination on account of tiredness and exhaustion.