Effect of Skewed Signalised T–intersection on Traffic Delay

Abstract

Intersections are places where two or more highways intersect. Their performance dictates the performance of the rest of the traffic network. When two highways cannot intersect at right angles due to some geometric constraints, skewed intersection forms. Generally a traffic signal system is designed to control traffic movements at road intersections without considering the orientation of the intersection. Such an approach might lead to inaccurate assessment of operational performance of a signalised intersection because such a configuration influences turning radius and hence the vehicle’s negotiation speeds. This paper describes the result of a study carried out to evaluate the effect of orientation of a signalised intersection on the control delay to vehicular traffic. The evaluation was carried out using aaSIDRA software, which was calibrated using the data collected from site. Two models of skewed intersection based on a normal T–intersection were simulated at minor approach at 45^º (i.e. skewed to the left), and 135^º (i.e. skewed to the right), respectively. The result of the analysis showed that delay to the motorists in the minor approach increases when the minor approach is skewed from left to right..