Study On The Equilibrium Model Of Asymmetric Polycentric City System And The Impact Of Rail Transit Investment

In recent years,with the completion of a moderately prosperous society and the acceleration of urbanization,China’s urban population is increasingly concentrated,with 18 "mega cities" with a resident population of 10 million or more,accompanied by serious traffic congestion and other "urban diseases".In order to alleviate the increasingly serious traffic congestion problem,the government has vigorously strengthened the investment and construction of urban rail transit in recent years.According to the statistics of China Urban Rail Transit Association,by the end of 2021,a total of 9192.62 km of rail transit lines were in operation in 50 cities in Chinese mainland,and 1222.92 km of new urban rail transit lines were added in 2021.The investment in rail transit will have an important impact on the residential location selection behavior of residents,which in turn will affect the housing price and spatial layout of the city.For this reason,there is an urgent need to address the issue of how rail transit investment affects residents’ travel choices,residential location selection,housing prices and spatial layout of cities,especially in mega-cities with multiple commercial centers.Current studies on urban system equilibrium models focus on the urban structure of a single commercial center,and the few studies on cities with polycentric structure also assume that the wage level of residents is externally given,and few studies endogenously determine labor wages through the equilibrium of supply and demand in the labor market,and few studies consider the influence of agglomeration economy in enterprise production.To this end,this paper first establishes an equilibrium model of a polycentric city system with asymmetric economic levels,compares the performance of the city system before and after the introduction of rail transit,and analyzes the effects of relevant parameters on the distribution of residents,labor mobility,and the number of people commuting across regions within the polycentric city system;then,it establishes an equilibrium model of a polycentric city system that considers the environmental quality of the place of residence,and analyzes the factors of the residential environment.The impact of residential environment factors on the location of residents and the location of jobs is analyzed.Finally,the corresponding solution algorithms for each model are designed,and numerical examples are used to demonstrate the solution and application of the models.The results of the study show that the introduction of rail transportation makes the dominant center more attractive to the labor force,further widening the gap between the economic levels of the business centers,and residents and labor force will spontaneously migrate to the area where the dominant center is located;the strengthening of the agglomeration economic effect and the increase of fixed input from the dominant center will make the economic levels of the two centers more unbalanced,i.e.,the dominant business center is stronger,and residents and labor force will move more to the dominant center.The improvement of transportation conditions makes residents accept long-distance commuting and spontaneously migrate to noncenter areas,and the city tends to "expand" outward.This paper expands the asymmetric polycentric city system equilibrium model by constructing an asymmetric polycentric city system equilibrium model,taking into account the influence of business centers and agglomeration economies with asymmetric economic levels.The results of the study can provide scientific theoretical basis and guidance for the government to plan rail transportation investment.