Research On Coordinated Control Of On-ramp Of Urban Elevated Expressway And Adjacent Ground Intersections

As the main artery of the urban road,the expressway is a relatively closed urban road system.The urban expressway is generally constructed in an elevated form and has no traffic lights on the whole line,and is connected with the ground road system by means of interchange.However,this type of construction and the form of traffic organization also restrict the conversion of the main road traffic flow between the ground road and the urban elevated expressway.When the traffic volume is large,the expressway entrance and exit ramp will become a traffic bottleneck section,causing traffic congestion and even appearing.The on-ramp queues traffic to the ground section,causing regional traffic congestion and affecting the operational efficiency of the entire road network.On the basis of previous studies,this paper considers that most urban expressway on-ramp and ground intersections are connected,so the traffic conditions of adjacent ground intersections are also largely the traffic conditions of expressway on-ramp.Have an impact.Therefore,in the control of the elevated expressway on-ramp,this paper comprehensively considers the traffic conditions of the main line,the on-ramp and the ground intersection,establishes a coordinated control model,improves the traffic efficiency of the expressway system,and reduces the occurrence of traffic accidents and congestion.In practical applications,Has an important meaning.In the research process,the paper first analyzes the traffic characteristics of the study area,including the connection mode between the express road and the conventional road,and studies the traffic flow characteristics of the area.The basis of coordinated control research is the single point control method,so it is of great significance to study the control methods of on-ramps and intersections.The third part of the thesis first analyzes the basic principle of the on-ramp control and the role of the on-ramp control.Then it analyzes the existing on-ramp control methods,including the timing control method and the induction control method.Finally,the ground intersection control scheme is introduced.It provides a theoretical basis for the study of coordinated control.Because of the complexity of regional traffic flow in this paper,if a complex coordination control model is established,it will be too difficult to solve due to parameters,targets and constraints.Therefore,this paper simplifies the model and proposes a hierarchical coordinated control model.When the length of the associated phase queue at the on-ramp or intersection reaches a critical value,the coordinated control scheme is started to avoid waste of road resources.In this paper,the ALINEA optimization control model based on queuing adjustment is adopted for the on-ramp,which avoids the phenomenon of queue length overflow of ALINEA control algorithm.The signal control of the ground crossing also adds consideration to the queue length of the on-ramp and the length of the queue associated with the ramp.Intersection traffic can enter the ramp reasonably,avoiding the occurrence of long queues in the traffic between the ramp and the intersection.In order to verify the rationality of the model,the VISSIM software combined with the VBA programming language,through the micro-simulation of coordinated control and uncoordinated control,found that the network delay,travel time,queue length,etc.after the coordinated control were significantly improved.A good control effect was obtained and the rationality of the coordinated control model was verified.