Optimizing Performance at Signalized Intersections through Signal Coordination in Two Intersections of Nepal

Abstract

Intersections in urban areas can often cause significant traffic delays due to the multiple directions of traffic flow. The Kathmandu Valley experiences chronic gridlock and congestion. This study aims to improve traffic flow at two busy intersections (Kanti Children's Hospital and Shital Niwas) in Kathmandu Valley, Nepal through evaluation of the existing traffic flow condition and reducing delays and queues using various alternatives and including signal coordination. A survey was carried out to collect morning peak hour traffic volume and geometrical features of the two intersections and developed a signalized intersection model in SIDRA software. The model was validated based on observed and modelled queue lengths for each approach, and the existing performance of the intersections was evaluated. Various alternatives were then developed to improve the performance of the intersections. Results showed that coordinating the signal systems significantly reduced the average delay time and maximum queue length at both intersections. Specifically, the average delay time was reduced from 106 seconds per vehicle to 26.5 seconds per vehicle at the Shital Nivas intersection and from 43.1 seconds per vehicle to 21.7 seconds per vehicle at Kanti Children's Hospital intersection. Similarly, the maximum queue length was reduced from 744.7 meters to 122 meters at the Shital Nivas intersection and from 456.2 meters to 147.7 meters at Kanti Children's Hospital intersection.