Influencing Factors And Model Optimization Of Expressway Access Capacity

Since the beginning of the new century,the urban expressway has become the focus of the urbanization.The urban expressways are high level road built for medium and large amount,long distance and high-speed traffic.Under the influence of many factors,the urban expressway in reality can not achieve the expected fast and large flow target.The capacity of expressway entrance and exit has become the bottleneck of the overall capacity of urban expressway system.This paper reviews the research results and related theories of road capacity.On this basis,according to the characteristics and ideal conditions of expressway,the influence factors of road condition,traffic facilities,traffic operation state and traffic environment are analyzed in detail according to the complexity and diversity of the influencing factors of expressway entrance and exit capacity.Select the influencing factors of expressway capacity index and determine its weight.According to the relative weight of the sorting,and then identify the main factors affecting the capacity of the expressway entrance and exit.Among them,the distance between entrance and exit and the type of combination have the greatest influence on the capacity of expressway entrance and exit.Therefore,this paper mainly considers the influence of these two factors on the capacity of the entrance and exit to optimize the model.The advantages and disadvantages of the ramp capacity model based on the service level method,gap acceptance theory and dynamics theory are compared.Optimization of the capacity model based on the dynamic theory of the entrance and exit ramp connection is selected.The capacity model of freeway junction at the entrance and exit is established,and the parameters of the model are explained.The model analysis and simulation experiment of the entrance and exit of expressway are carried out.By analyzing the simulation data,the capacity reduction factor and speed reduction corresponding to the distance between the entrances and exits of each type of expressway are obtained.The recommended value of the distance between the entrance and exit is given.According to the reduction factor,the range of the recommended values of the model parameters is presented.The simulation experiment verifies the influence of the setting form of the expressway entrance and exit on the traffic capacity.Finally,combined with the urban expressway system planning and rapid transformation project of Jiangmen core city to verify.The planning scheme is evaluated and analyzed,and the node layout is analyzed.The optimal recommendation scheme is put forward in terms of the distance between important nodes and the type of combination.