| Urban expressways can provide vehicles with safe,fast and efficient driving services,and are currently an effective means to alleviate urban traffic congestion.Therefore,it is very important to ensure the efficient operation of urban expressways.The traffic flow of the on/offramp of the expressway will affect the traffic efficiency of the main road.At the same time,the on-ramp of the expressway is connected with the ground traffic,which will also affect the traffic efficiency of the ground traffic.Based on the analysis of the connection characteristics of ramps and ground traffic and related control strategies,this paper proposes coordinated control strategies for on-ramps and intersections,off-ramps and intersections,and on-ramps and intersections.The coordinated control strategy can optimize the signal timing of intersections or intersections and on-ramps.The signal timing can reduce vehicle delays at intersections and expressways,improve the traffic capacity of intersections and expressways,and effectively improve the speed of intersections and expressways.traffic efficiency.From the content point of view,this article is mainly divided into three parts:(1)A coordinated control strategy for off-ramps and intersections is proposed.In order to prevent the off-ramp vehicle queuing overflow and improve the traffic efficiency of expressways and intersections,this paper establishes a multi-objective optimization model by maximizing the traffic capacity of the intersection,minimizing the intersection delay and the vehicle queuing length at the entrance of the intersection where the off-ramp is located.The optimized signal timing at the intersection can effectively prevent off-ramp queuing overflow and improve the traffic efficiency at the intersection.(2)A coordinated control strategy for on-ramps and intersections is proposed.In order to reduce the impact of on-ramp traffic flow on expressways and intersections,this paper maximizes the capacity of intersections,minimizes intersection delays,the difference between critical occupancy and the downstream occupancy of the on-ramp and main road junction area,and the off-ramp The vehicle queue length at the entrance of the intersection where the vehicle is located,establishes a multi-objective optimization model.The optimized intersection signal timing and on-ramp signal timing can simultaneously reduce the impact of on-ramp vehicles on expressway and intersection traffic efficiency.(3)A coordinated control strategy for off-ramps,on-ramps and intersections is proposed.In order to reduce the impact of on/off-ramp traffic flow on expressways and intersections,this paper maximizes the capacity of intersections,minimizes intersection delays,the difference between critical occupancy and the downstream occupancy of the on-ramp and main road junction area,and the off-ramp The vehicle queue length at the entrance of the intersection where the vehicle is located,establishes a multi-objective optimization model.The optimized intersection signal timing and on-ramp signal timing can improve the traffic efficiency of expressways and intersections at the same time.Taking the intersection of Laodong South Road and Gaoxin Road and the adjacent pair of on and off-ramps in the west section of Second Ring South Road in Xi’an as simulation scenario,the three coordinated control strategies mentioned in the paper are simulated and verified in the VISSIM.The simulation results show that compared with the Webster timing and the actual signal timing at the intersection,the three coordinated control strategies can reduce the vehicle delay at the intersection and expressway,and improve the traffic capacity of the intersection and expressway. |
