Noncoordinated Phases in Coordinated Traffic Signal System: Evaluation of Alternative Permissive Periods on Performance

Currently, there is no standard nomenclature to describe coordination modes. Different traffic signal controller manufacturers use various terms, and the terms are not always easily understood. Furthermore, there is no documented understanding of the effectiveness of alternative approaches. The purpose of this study is to investigate the main issues related to noncoordinated movements of coordinated semiactuated traffic signals. A set of consistent terms and definitions is proposed. Based on this terminology, three coordination modes are presented, and their performance is evaluated for three different volume-to-capacity (v:c) ratios by using hardware-in-the-loop simulation. With average vehicle delay as the measure of effectiveness, results suggest that for lower v:c ratios, the modes perform differently. This paper provides some guidance on the use of coordinated semiactuated traffic signal operation by making traffic engineers aware of how different coordination modes can affect intersection performance.