Analysis Of The Relationship Between Urban Rail Transit Development And Urban Polycentricity In Wuhan

At present is still in the stage of rapid urbanization in China,a new type of urbanization in the country put forward the people-oriented,pay attention to the quality of urbanization,the disadvantages of traditional single centers of big cities layout is increasingly serious,and many big cities have proposed a polycentric spatial structure strategy.The transformation of urban spatial structure needs the corresponding transportation mode to support.As a new and rapid public transport mode,which can reduce the pressure on urban traffic,guides the land development,optimize the structure of city,rail transit has become the focus of many big city transportation development direction.What is the relationship between urban rail transit development and urban polycentrality?Most of the previous studies are qualitative analysis,and then the evolution models between the two are summarized.The aim of this paper is to measure the change of the self effect of rail transit and the change of urban poly centrality by means of quantitative method,and then reveal the coupling relationship between the two.Wuhan is the largest city in the central region and the first city to build a subway in Central China.In recent years,wuhan rail transit has developed particularly rapidly.This paper,taking the Wuhan Urban Development Zone as the research object,first combs the related research and theory of urban rail transit and urban polycentrality,clarified and defined the connotation of the category and polycentrality of urban rail transit,and reveals the mechanism of interaction between the two parties from three perspectives:demand and supply,adaptation and guidance,support and optimization.Then the effect and pattern evolution of the 2000-2017 year rail transit development are measured in detail from three aspects:the development of its own attributes,the centrality of the rail site location and the accessibility of the street.The spatial distribution pattern of urban population and light from 2000 to 2017 is measured by two indexes of street population density and street average light intensity,and the population distribution pattern is fitted by single center and multi center population density model,and urban polycentrality is measured by the method of position order and scale distribution.Then,from the perspective of space and statistics,the relationship between urban rail transit development and urban polycentrality is quantitatively revealed by using bivariate spatial autocorrelation model and curve estimation.Finally,according to the accessibility indicators of 2025,the urban population distribution pattern and urban polycentrality of the city may be predicted in 2025.The main conclusions are as follows:(1)from 2000 to 2017,the overall location centrality of Wuhan rail stations was rising,but the increase in different regions of different index was different.With the improvement of rail traffic,the differences between the location centrality of each site increased first and then decreased,and the overall trend was more balanced.(2)the overall accessibility of Wuhan urban development zone shows a core edge distribution pattern,and the overall accessibility is increasing.However,the accessibility of the streets is expanding before 2013,and then tends to be stable after 2013.The overall increase of accessibility in Jiangbei area is higher than that in the south of the Yangtze River.(3)the population density of the Urban Development Zone in Wuhan has a core edge distribution pattern.From 2005 to 2016,the accumulation capacity of the main center rose first and began to decline,and there was a clear main center before 2013,but the trend of diffusion began after 2013.Before 2013,the population polycentrality of the main urban areas of Wuhan was declining.With the gradual improvement of the rail transit,the development of the main and secondary centers began to balance,the city polycentrality began to increase,and the Wuhan is now in the stage of gradual enhancement of polycentrality.The distribution pattern of average intensity of light is consistent with the distribution trend of population density.(4)there is spatial agglomeration between neighboring centricity,intermediary centricity and population density of the site location,while there is only a slight spatial correlation between the direct centrality and the population density around it.The cubic function model can well fit the relationship between logarithm of population density and average travel time and daily accessibility,while the relationship between the logarithm of population density and population potential can be well fitted by the quadratic model.(5)in 2025,the differences in the location of the site of Wuhan urban development zone were further narrowed,the accessibility of each site was further balanced,and the distribution pattern of the site centricity was more dispersed.With the further improvement of rail transit network,the indicators of accessibility will be greatly improved.The population spatial distribution pattern of the Wuhan Urban Development Zone in 2025 will be more balanced,and the urban polycentrality will continue to increase.