Bus Signal Priority Control Of Intersections On Regional Boundary Using Timed Colored Petri Net

Urban traffic system is quite difficult to be modeled and controlled considering all intersections together,which is an classic open system composed of passengers,vehicles and traffic infrastructures..In this paper,a bus signal priority control model based on Timed Colored Petri Net(TCPN)for sub-region boundary intersections is proposed to investigate the whole process of transition from macro sub-region perimeter control to micro signal control of each intersection unit with sub-region as the research object.The main contents are as followings.Firstly,the dynamic process of subregion level macroscopic traffic flow is described with TCPN,and proposed dynamic traffic flow model based on the conservation equation of the cumulative number of vehicles in subregion.The MFD as the analysis tool to evaluate road network traffic state,using MPC to obtain the optimal perimeter Control parameters of each Control step in the finite Control time domain,and restricting the transfer vehicles into the control area,the traffic situation in the sub-area can be effectively controlled.Secondly,the main intersections on the boundary of sub-area were selected as the research object,and the process of vehicle arrival,waiting and passing at the intersection was described by using TCPN.Three different signal control strategies of "fixed master signal control","adaptive master signal control","adaptive master signal + bus pre-signal control" are mainly given,and the signal control model is established,which is helpful to realize the behavior simulation of the traffic flow in the border intersections.Finally,taking part of the road network in Tianhe district of Guangzhou as the research object,the top-down control strategy from perimeter control to signal control is verified by using Python under different demands.Simulation results show that:(1)The perimeter control method can balance the vehicle density in the sub region,improve the vehicle travel speed and clear the accumulated vehicles in the region faster;(2)Taking the minimum difference between the expected number of transferred vehicles and the actual number of transferred vehicles as the control objective,the main signal optimization control of the intersections at the boundary of the sub area can reduce the number of vehicles waiting in the intersections;(3)The effect of implementing the control strategy of "main signal + bus pre signal" in the border intersections of the sub district is related to the demand level.In the case of low demand,this strategy can effectively reduce the waiting time per capita at intersections without causing a large number of social vehicles to be stranded;While in the case of high demand,this strategy will cause the waiting time of social vehicles at intersections to increase,which will lead to the increase of waiting time per capita.