An Simulation Study On Urban Traffic Congestion Pricing Policy Model Considering Logistics Vehicles

The process of "new urbanization" is advancing rapidly,the passenger transport demand of residents in commuting,social events and other aspects continues to grow,and the logistics demand to meet the needs of residents’ life,such as fast retailing and e-commerce distribution,also increases rapidly.The resulting traffic congestion has become a bottleneck restricting the overall development of the city,leading to huge waste,time delay,environmental pollution and loss of health.In order to alleviate traffic congestion,many cities have carried out beneficial exploration.As one of the effective means of traffic demand management,traffic congestion pricing policy internalizes external costs based on negative economic incentives,which has important practical significance to crack the dilemma of urban traffic congestion.Urban transportation system consists of urban freight and urban passenger transport.Urban traffic system is a complex nonlinear dynamic system affected by population,economy,environment and other factors.The change of any element of the system will lead to a change in others,which is difficult to cope with by traditional methods.Moreover,previous studies rarely considered the impact of logistics systems on urban traffic.Based on the above mentioned,this thesis analyzes the formation mechanism and negative externality of urban traffic congestion,uses system dynamics thinking to determine the interaction mechanism of subsystems,and divides the model structure,constructs the system dynamics model of urban traffic congestion pricing considering logistics vehicles,taking advantage of Vensim PLE simulation software.The model includes three kinds of external costs: time delay,pollution emission and health loss caused by traffic congestion.Poisson regression model in air pollution epidemiology as well as BPR impedance function are used to quantify the health loss and cost of time delay respectively,and the cost of pollution emission is measured by emission factors.The model takes Xi’an as an example for simulation experiments,and sets dynamic simulation parameters of congestion pricing policy.By the comparative analysis of simulation results under different pricing,proposes the optimal charging level,and calculates the external cost caused by urban traffic congestion.Afterwards,the charge rate is applied to the actual road network to verify the feasibility and rationality of the urban traffic congestion pricing policy.The experimental results show that: when the private car charges 8-9 yuan,while the logistics vehicle charges 16-18 yuan,the amount of urban motor vehicle traffic volume will drop by 42%-46%,the average speed of urban motor vehicles can reach 30km/h,and the road condition will be basically smooth.After implementing congestion charge policy,the negative external cost of urban traffic congestion will be reduced by 86.84% until 2025.With the charge rate applied to the actual road network and the congestion pricing policy implemented,the road service level is between 0.6-0.75,which can effectively reduce the delay and alleviate the congestion.