Quantifying the benefits of coordinated actuated traffic signal systems : a case study.

Coordinated actuated traffic signal systems have been widely implemented for the past few decades because they provide better progression along the major corridors through proper coordination. However, little has been done to quantify the benefits that can be obtained from coordinated traffic signal systems. Most efforts reported in the literature focused on system performance estimated from simulation software as opposed to field studies. The purpose of this study was to quantify the benefits of coordinated actuated traffic signal systems by conducting an analysis of before-and-after data. The travel time on the coordinated arterials and the stopped delay on a few key approaches were selected as measures of effectiveness. Synchro, a macroscopic traffic signal timing evaluation and optimization software, was used to generate the coordinated actuated traffic signal timing plans for comparison purposes. In addition, the performance of an adaptive split feature, implemented within the coordinated actuated traffic signal system, was evaluated through a before and after study. The data showed an improvement in performance of the coordinated actuated system over the actuated isolated system (the before condition), including a 30 percent reduction in travel times on the coordinated corridor. There was a corresponding increase in stopped delay on non-coordinated approaches, but the addition of the adaptive split feature was able to reduce this delay by 40 percent at one site without impacting progression on the coordinated approaches. The study recommends that the Virginia Department of Transportation regional traffic engineers implement the coordinated actuated traffic signal system over the non-coordinated system and the adaptive split feature with the coordination to reduce delays on side street approaches. Further, a cost/benefit analysis indicated that the coordinated actuated traffic signal system has a benefit/cost ratio of 461.3 when compared to the non-coordinated actuated traffic signal system. (Author/publisher)