Modelling and Optimization of Traffic Flows at an Urban Intersection Using Vissim Simulations and CAD Software

Abstract

Urban Intersections are the hub of business and community activity that regulates various conflicting traffic movements to avoid delays. IJP Road – a 10 KM long major arterial situated at the junction of twin cities of Rawalpindi-Islamabad attracts considerable amount of inter- and intra-cities commuters and freight movement. This road segment carries a sizeable volume of heterogeneous traffic including autos, motorbikes, vans, busses and slow-moving trucks/trailers. A signalized intersection with long cycle length at the junction of 9th Avenue and IJP Road causes considerable delays due to congestion and generates long queues not dissipating in the allocated green time. The problem is further aggravated due externalities of traffic safety and environmental degradations at the intersection. In order to mitigate the stated issues, this study evaluated the traffic conditions with a view to suggest measures to improve the traffic flow conditions at the intersection using traffic simulations, traffic management strategies and geometric design improvements. The turning movement data at the selected intersection was collected using Video Counts and evaluated using PTV VISSM 9® which yielded level of service (LOS) “F” at the intersection with recurring queues. VISSIM was further employed to model and evaluate various alternatives in order to improve the LOS. These alternatives comprised short-term (low cost minor interventions) to long-term (high cost major interventions) including optimization of signal timings, adding extra lanes on 9th Avenue and IJP Road to enhance capacity as well as construction of a gradeseparated facility. Each alternative was modelled and evaluated for its efficiency and effectiveness and the best alternative was selected based upon selected performance indicator of LOS as long-term measure of effectiveness at present and future projected scenarios. The geometric design of grade separated facility was proposed using