Control strategies for transit priority based on queue modeling and surrogate testing

To explore the potential benefits of bus priority based on signal phasing strategy, this article proposes a simplified statistical sampling method to simulate vehicle delays at intersections instead of using conventional microscopic traffic simulations. This method greatly reduces the calculation cost and time while maintaining the estimation accuracy of the delay. This research provides a surrogate testing system and tests intuitive traffic signal phasing strategies that shorten average waiting time of queuing vehicles by letting certain buses pass the intersection with a higher priority. Interestingly, the results reveal that the length of the green time should be adaptive with the proportion of buses in the traffic flow. Moreover, a higher priority is suggested for the bus at certain positions in a queue so that it can pass the intersection in one green period with its preceding vehicles. The benefits of this approach include (1) reduced delay of both buses and other vehicles when the proportion of buses is small; (2) keeping the influence on network-wide traffic at a low level even when the proportion of buses is large, because the green time is only extended for a short while; and (3) ease to implement such control strategies by modifying current traffic control systems.