Optimal cycle model based on active transit signal priority strategies with artery coordination

Studies on active transit signal priority (active TSP) focus primarily on the advantages and parameters of priority strategies within a given cycle time, which is not necessarily the optimal cycle. With consideration for the restrictions resulting from arterial coordination, the effect of three active TSP strategies on vehicle delays at a key intersection on an arterial road was discussed. Using an actual case, the effect of possible real volume variations on optimal cycles under active TSP strategies was analyzed. Results show that under special flow conditions, additional benefits exist when the cycle time is increased from the value generated by the TRRL approach. The extent of increase can rise with the ratio of priority phase flow to nonpriority phase flow. Cycle time can be dynamically established in accordance with the flow conditions in actual operations. The findings also show that the efficacy of red truncation is better than that of green extension.