Research Of The "Feedback-Variable" Control Method Of Speed Limit On Heavy Rainfall And System

At present,the problems of traffic congestion and safety are highlighted in China.After study,bad weather conditions,such as:heavy rainfall,are the main factors causing traffic jams and frequent accidents.However,in China,the control method of legal speed limit is used usually on the highway.Thus,it results in a serious threat to road safety and traffic efficiency that the value of speed limit can’t be adjusted dynamically based on traffic and weather conditions.This paper relies on the project of Science and Technology Department:the demonstration system of road traffic sensor network information detection,mining,convergence,post and decision support,and research has important theoretical significance and application value.This paper describes various freeway traffic flow models and control methods of speed limit,and it analyzes some deficiencies.For example,the existing models can’t adjust the traffic flow parameters according to the actual traffic environment,and the speed limit value is not only stationary but also its accuracy is not high.This paper puts forward the rainy macroscopic dynamic traffic flow model and the feedback control method of variable speed limit,on how to improve the model with static parameters and optimize the control method of speed limit.This paper evaluates the accuracy of the model and the effectiveness of the control method by the MATLAB.Main tasks are as follows:1)Considering the deficiency that METANET dynamic traffic flow model can’t adjust the traffic flow parameters according to the actual traffic environment,this paper analyzes the impact of rainfall on traffic and the relationship between rainfall intensity and traffic flow parameters,replaces static traffic flow parameters with dynamic traffic flow parameters,and establishes a rainy highway macroscopic dynamic traffic flow model.2)Considering the deficiency that speed limit value is stationary and its accuracy is not high,this paper analyzes the spatial relationship of the upstream and downstream,determines the traffic flow of upstream based on the maximum capacity of heavy rainfall sections,feeds back the live information of heavy rainfall sections and replaces the top-down model with the down-top feedback mode.Thus,the new method improves the traffic congestion.3)This paper sets up tow experiments:one is that highway simulation experiments of METANET model and the improved METANET model under the conditions of rains and no control measures,another is that highway simulation experiments of no control method,optimal control method,control method of fixed speed limit,feedback control method of variable speed limit.The results show that the improved model can reflect better highway actual vehicle situation in the rain.4)From the perspective of managers and users of the highway,This paper conducts needs analysis,divides the module,analyzes key technologies,and designs the overall program of the system the feedback control method of variable speed limit in the heavy rainfall sections.The major contributions of this paper are as follows:1)This paper establishes a rainy highway macroscopic dynamic traffic flow model.It solves the problem that model can’t adjust the traffic flow parameters according to the actual traffic environment.Thus,the new model can better reflect the actual situation of freeway traffic flow in the rain.2)This paper comes up with the control method of feedback speed limit.It solves the problem that speed limit value is stationary and its accuracy is not high,to improve the efficiency of heavy rainfall sections.Thus,Total Time Spent(TTS)has 14.8%improvement,compares to that in the case of simple control method.