Research On Freeway Congestion Mechanism And Ramp Control

The rapid development of economy drives the overall improvement of the national economy.In recent years,the number of cars in china has been increasing immediately,the positive effect of this situation is that the efficiency of residents is generally improved,but the negative effect is that the congestion is more seriously.Our country's freeway traffic congestion is particularly serious,especially during the holiday and the daily traffic peak period,this kind of traffic congestion has already developed into a kind of frequent traffic congestion.It has already become a difficult problem how to alleviate the freeway congestion effectively.Now,the on-ramp control method is one of the most effective means to alleviate this congestion problem.The effects of the on-ramp control method on relieving the traffic pressure on the main line of the freeway was studied by analyzing the traffic flow characteristics of the freeway.The main work of this paper is as follows:Firstly,the reasons for the congestion of Chang-Yi Freeway on the marco level were analyzed in the three aspects:the main line flow distribution,the interworking distance setting and the on-ramp flow distribution based on the actual traffic data of Chang-Yi Freeway-The traffic flow characteristics in the merge area of the on-ramp was analyzed by the traffic wave theory on the micro level.Then,the macroscopic traffic flow characteristics of the freeway and the types of traffic flow model suitable for the freeway were analyzed.A kind of macroscopic traffic flow model suitable for single-point ramp control was proposed,which was based on the Markos Papageorgiou's macroscopic traffic flow model.After comparing the existing research method,the PID ramp control method based on the particle swarm optimization algorithm with faster convergence speed was chosen.At the same time,the PID ramp control system based on the BP neural network algorithm and single neuron algorithm were used to simulate under the real data of Chang-Yi freeway,and the results of the two ramp control system were compared.The results proved that the particle swarm optimization algorithm has faster convergence speed and better convergence effects.At last,because of the existing shortcomings of the single ramp control method in freeway system,the research on the multi-ramp coordinated control is necessary.A PID multi-ramp coordinated control method based on particle swarm optimization algorithm was proposed to solve the deficiency of the single ramp control method.And the effectiveness of this method under the data of Chang-Yi freeway was verified.