Pre-Control Strategies for Downstream Bus Service Reliability With Traffic Signal

As an undesired behavior of the transport system, headway fluctuation or even bus bunching reduce reliability of bus stop service for waiting passengers. This paper proposes a pre-control method to improve the balance of service intervals at downstream stop through an adjustment of green time for bus passing, in which priority and delay of bus passing can be achieved. The proposed pre-control strategies at intersection are triggered based on prediction of service intervals at downstream stop to select priority or delay strategy that includes adjusting starting and ending time of green light. Meanwhile, the influence of adjustment of green time on surrounding traffic delay of vehicle is also considered. The traffic delay is estimated for vehicles arriving during phases within associated two signal cycles induced by the signal adjustment. To derive optimal adjustment of green time, a multi-objective function is established and the objectives include deviation of the bus service intervals and traffic average delay. An exhaustive search algorithm is programmed to solve the objective function. The effects of control strategies are tested by numerical experiments based upon a real bus route in Changchun. Results show that the bus service reliability can be improved through a proper signal pre-control and, compared with the single control strategy with only bus delay, the standard deviations of service intervals with the average running time and the stochastic running time are improved by 8.53% and 7.31%, respectively.