The Spatiotemporal Evolution Of The Central Plains Urban Agglomeration’s From A City Network Structure Perspective Of Railway Traffic Flow

Promoting the flow of factors between cities in the post-epidemic era is of great significance to economic recovery and the formation of a domestic cycle.Transportation is the key to promoting the flow of factors within the urban agglomeration as a smooth spatial cycle.If the railway planning is unreasonable and the development is relatively lagging,it will be difficult to adapt to the demand for traffic caused by the flow of factors between cities,which will affect the regional economic development.Therefore,through the study of urban spatial structure from the perspective of traffic flow,it is of great significance to rationalize the relationship between regional cities and organize the cooperation and division of tools within the urban agglomeration.Existing studies mostly focus on the urban scale,select economically developed areas and study the urban network of a single time section based on a static model.Therefore,the study takes the county as the scale and the Central Plains urban agglomeration as the research object,constructs the dynamic railway passenger traffic flow from 2000 to 2020 based on the train frequency data,and uses social network and model measurement methods.This paper explores the evolution characteristics of ordinary railways,high-speed railways and the comprehensive transportation network formed by the two,and takes 2020 as an example to analyze the network connection characteristics within and between core development areas and coordinated development areas.The main conclusions are as follows:During the development process of ordinary railway and high-speed railway network,the status in the network,the symmetry of urban connection and the network balance showed:(1)The dominant position of ordinary railway continued to decline after the emergence of high-speed railway,but the status of high-speed railway continued to rise.(2)The asymmetry of urban connections between ordinary railways and high-speed railways is becoming more and more significant.(3)The disequilibrium of the connection between ordinary railways is relatively large in general,but the fluctuation is small over time,while the disequilibrium of high-speed railways increases sharply.From the perspective of comprehensive traffic flow,the urban network shows in terms of network density,node centrality,axis,and spatial clustering:(1)The connection network is continuously encrypted,and the overall imbalance is intensified.(2)The "Matthew effect" of urban centrality is prominent,and the hierarchy is becoming more and more obvious.(3)The overall urban intermediary centrality is weakened,but the value of high intermediary cities fluctuates greatly.(4)The strength of the connection between cities is becoming more and more unbalanced.The development axes of Longhai and Beijing-Guangzhou are prominent,and the role of the Beijing-Kowloon line and the axis of the Zheng-Fu high-speed railway is gradually emerging;with the opening of high-speed railways,high-level city-pairs appear“hyperspace” connections.(5)The first contact pattern has the dual characteristics of "field" and "flow",and the characteristic of "flow" tends to be more obvious.(6)The core area is mainly concentrated near the Longhai and Beijing-Guangzhou lines,which continue to spread to the Beijing-Kowloon line and converge to some extent;the changes of the agglomerated subgroups mainly depend on the changes of railways,and have the characteristics of geographical proximity and jumping.In order to explore whether the transportation city network conforms to the relevant planning,taking 2020 as an example,the transportation network structure presents:(1)Nodes: Zhengzhou is seriously polarized,and the gap between the secondary center and the core city is large.(2)Connection line: The city in the core development zone is weakly connected with Zhengzhou,the linkage between Luoyang and the northwestern cities is not strong,the "rice-shaped" development axis is immature,and the position of the Beijing-Kowloon line axis is obvious.(3)Grouping:The core area is distributed in a "t" shape,and is divided into three parts: east,middle and west.(4)Core and coordinated development areas,within the region: obvious extroversion,and large differences in the scale of internal connections.In the middle,east,south,west and northern regions,the pattern of strong multi-nucleus,sub-strong single-nucleus,weak and no obvious polar nucleus,weak and no obvious polar nucleus,and sub-strong single-nucleus were formed respectively.Inter-regional: The four regions are strongly connected with the core region,and the four regions are weakly connected.