Improving the efficiency of an intersection through traffic signal phasing arrangement when no separate right turn lanes available

Abstract

Traffic congestion has resulted in significant losses to the economies worldwide with the valuable time lost on the roads. Nevertheless, significant capacity improvements at the intersections can be obtained through the implementation of proper traffic management initiatives. In terms of traffic signal designs, considerable delay reductions can be obtained through optimum signal phasing arrangement. The research aims to develop a set of guidelines to be followed in phase sequencing in traffic signal designs, when no separate right turn lane is available. Grounding the theoretical aspects of traffic signal design, the research considers the effects of different phasing arrangements for right turns such as total through plus right turn phase, leading green for right turns only phase and lagging green for right turns only phase, when no separate right turn lane is available at a signalized intersection. Using Webster’s theoretical framework for traffic signals and delay estimations, the cycle time reductions and the respective delay reductions were obtained. A traffic micro simulation was also conducted using VISSIM micro simulation software for further analysis and verification purposes. It was observed that leading green for right turns only phase would work only when the right turn percentage is less than 15%. Considerable delay reductions can also be obtained through proper selection of phasing arrangements, depending on varying traffic volumes and right turn percentages.