Microscopic Simulation Based Assessment of the Level of Service at a Signalised intersection (a Case Study of Wandegeya Intersection)

Abstract

Signalized intersections are one of the critical elements of an urban transportation system and network. The performance of these intersections is a great input to the city planners and traffic engineers to efficiently allocate resources towards their improvement if needed. The determination of the level of service (LOS) is complex due to uncertainties in traffic flow and the difficulty to collect data for the parameters that determines the LOS. The main objective of this research was to use the simulation-based approach to determine the LOS at a signalized intersection. The specific objectives for this study included, examination of the existing phasing and timing of the intersection, determination of the volume of traffic that passes the intersection, development of a microscopic traffic simulation model and to use the output from the model to determine level of service of the Wandegeya intersection. To achieve these objectives, field studies were undertaken to collect traffic volumes in the morning, afternoon and the evening peak hours, geometric data of the intersection and the exiting timing and phasing of the intersection, to be used to calibrate the simulation model. A study was carried out at Wandegeya signalized intersection in Kampala, Uganda. The HCM methodology was used in the analysis of the collected data. The arrival rates of vehicles approaching the intersection were collected. The demand flow rates in vehicles per hour were computed and converted into passenger car units per hour and input into the PTV Vissim multimodal traffic simulation software to carry out simulations and produce the level of service of each approach and the entire intersection. The level of service for each movement and leg were generated from the simulations basing on the vehicle delay in seconds per vehicle. The overall level of service for the intersection was also computed basing on the average vehicle delay.