DELAY AT UNCONTROLLED INTERSECTIONS

Abstract

Delay is the most crucial aspect in judging the performance of any intersection. The delay at an unsignalized intersection may be divided into two parts; queue delay and service delay. In the absence of queue of vehicles at an intersection, service delay is the only component of delay to be estimated as a measure of performance of that intersection. The service delay at an unsignalized intersection is the time spent by a vehicle at the stop-line, waiting for sufficient gap in the conflicting traffic so as to clear the intersection safely. The service delay mainly depends upon the amount of conflicting traffic and its composition in terms of proportion of heavy vehicles. It also depends upon the geometric features of the intersection like number of lanes, lane width etc. Most of the previous delay studies for uncontrolled intersections were conducted on homogeneous and lane-disciplined traffic and their literature review suggested a need of delay study under mixed traffic conditions as prevailing in India. The present study introduces a service delay model based on microscopic analysis of delay data collected at five uncontrolled intersections located in different parts of the country. The delay data were divided into several parts according to the category of the subject approach vehicle and type of the movement. The service delay increases exponentially with the conflicting traffic. It was found that the proportion of heavy vehicles in the conflicting traffic greatly affects the service delay. The proposed delay model is compared with Kyte's linear model for service delay estimation. The delay values estimated by proposed model are found to be on lower side of those by Kyte's model up to a conflicting traffic volume of 3500 veh/hr, beyond which its prediction is above the Kyte's model and increases steadily.