Traffic congestion in U.S. cities has grown rapidly in recent years, and numerous solutions are needed to address the problem. New research is described for producing basic improvements in the practice of traffic signal timing design, which is one of the many available weapons for fighting congestion and delay. Models in the literature for predicting traffic-actuated phase times are oversimplified. In some cases, they do not recognize the signal settings associated with today's controllers, which affect phase times. In other cases, models from the literature do not recognize operational effects (for example, progression, queue blockage, permitted left turn, critical movement, early return to green, and stochastic effects) that affect phase times or that are applicable only to isolated signals instead of coordinated signals. Consequently, the recommended average phase times are not practical, and the resulting performance estimates and timing plan designs are unlikely to materialize in the field. The overall goal of this research is to describe and demonstrate an improved methodology for predicting actuated phase times. An improved methodology is needed to improve the overall timing plan design process. Experimental results indicate an improvement in the accuracy of actuated phase time calculation based on the improved methodology.
Abstract