Selection of Optimum Junction Operation Strategy for Gatambe Intersection Using VISSIM Simulation

Abstract

At present, traffic congestion is a major issue in the Kandy city area. It is observed that most of the congestion occurs at junctions and intersections. One of the most congested locations in the Kandy road network is the Gatambe junction. Under this research, the aim is to simulate the Peradeniya – Gatambe corridor using VISSIM simulation software and identify the optimum junction improvement strategy for the Gatambe intersection. Gatambe intersection is a four-way intersection that connects the Colombo – Kandy road (A1), William Gopallawa Mw (AB42) and Gannoruwa road (B365) directly. At present, the Gatambe intersection operates as a roundabout and at peak hours it is controlled manually by traffic police. Because of the heavy upstream traffic congestion near the Gatambe intersection, queues propagate upstream of the junction. Although many solutions including those needing heavy capital investment have been proposed to reduce congestion at Getambe junction, it is important that all possible solutions are tested on a simulation model before any physical implementation. In this study VISSIM is used as the simulation model. VISSIM is a microscopic simulation model that can predict network performance at the operational level, optimize control systems, and predict their behaviour before implementation. For simulation the necessary geometric and traffic data were collected as the first step. Then, the existing situation was simulated using VISSIM and the results validated with the observed survey queue length results. After that, the model was used to simulate three improvement strategies; signalization without geometric improvement, signalization with geometric improvement and grade separation. According to the delay results, the benefit of each alternative was estimated and a cost benefit analysis was conducted to identify optimum junction improvement strategy.