Research On Bus Priority Control Method Under Coordinate Control

With the development of national economy, urban transport problems become increasingly severe, more and more researchers have found that developing public transport was an important way to solve traffic congestion. Bus priority, as a major form for developing public transport, has been an important method to reduce the bus delay, improve the bus speed and service, at the same time it can attract more people to take buses. So it is of great significance to alleviate the cities' traffic congestion.The implementation of bus priority may have an impact on ordinary vehicles, especially for traffic flows in no-bus phase, if the selected priority strategy is inappropriate, it is prone to appear the phenomenon of pressure cars. At present, studies about bus priority aim at a single point control or the coordination control with bus lanes mostly, the single point bus priority only guarantees the optimal control effect at the single point, but without concern the coordination between these intersections, even the whole traffic network control. In our country, the large bus flow, the complexity traffic network, the complex bus lines mix with ordinary vehicles, at the same time the effect of the volatility of the bus travel time and bus stop time, all of these make that only choosing the coordination control methods in which public transportation is the main object hardly can get desirable effect.In order to combine the bus priority with the coordination control of traffic network, this paper focuses on how to propose effective bus priority control and a bus priority control model was put forward under the coordination. The model contains two layers: the upper gives the whole coordinated control strategy, and the lower, as an intersection control, contains two kinds of control methods (active priority and adaptive priority). Each method is controlled by the coordination and the parameters are adjusted appropriately. In the active bus priority model, the prediction accuracy of the bus travel time and its impact on the priority control are taken into account, and the priority time window is introduced as a judging condition to determine whether the priority should give or not, which can avoid the happen of invalid priority. In adaptive priority model, the idea of multi-objective optimization is applied to the control. Considering the total delay of passengers and the queue length, two objective function models of bus priority control are established, and MOPSO (Multi-objective particle swarm optimization) is selected for optimization, which can avoid the road congestion in no-priority phase due to the long queue. In the end, the two proposed control methods are simulated by VISSIM, the simulation results show that the two priority methods both can greatly reduced bus delays, and the impact of priority to the coordinated control is minimal on the whole.