Study On The Influence Of Transportation Infrastructure On The Spatial Structure Of Urban Agglomeration

The process of urbanization in our country has entered a new stage of spatial development dominated by urban agglomerations.The spatial structure of urban agglomerations has changed from single city dominance to multi-level central support.Coupled with the rapid construction of infrastructure in our country,such as railways,highways and shipping networks,has caused the accelerated flow of people,logistics and information flow between cities.This will further affect the spatial structure of the urban agglomerations of our country.Therefore,this has also triggered the following thoughts in this paper: What is the status quo and evolution trend of spatial structure of urban agglomerations in China? What is the impact of transportation infrastructure on the spatial structure of urban agglomeration? Does the effect vary among geographical units?Based on this,this paper takes 21 urban agglomerations in China as the research object.Firstly,standardized Herfindahl index method is used to measure the multi-center spatial structure of urban agglomerations in China from the dimensions of size,location and accessibility from 2000 to 2014,and then empirically tests the impact of transportation infrastructure on the spatial structure of urban agglomerations.Instrumental variable method is used to identify the causal relationship between the two.Finally,based on the two paths of agglomeration economy changed by transportation infrastructure,the intermediate mechanism of transportation infrastructure affecting the spatial structure of urban agglomeration is tested.The main conclusions are as follows:(1)The measurement results show that the urban agglomerations with high levels of multi-centralization spatial structure are Changzhu-Tan,west Coast of the Straits,Shandong Peninsula,Yangtze River Delta,Jianghuai region,Poyang Lake,Central Plains Economic Zone and Ningxia along the Yellow River.The urban agglomerations with low multi-center spatial structure are Beibu Gulf,Central Guizhou,Chengdu-Chongqing,Guanzhong-Tianshui and Wuhan urban agglomerations.(2)In the analysis of the evolution trend of the spatial structure of the urban system,it is found that the urban agglomerations with low multi-center spatial structure index have the tendency of developing to the single center.(3)The empirical results show that at the national level,transport infrastructure changes have no significant impact on the urban system,but for urban agglomerations in different regions,there is strong heterogeneity.Specifically,the improvement of transport infrastructure density can significantly promote the multi-center and flat development of urban spatial pattern in the east,while for the central urban agglomeration,the improvement of transport infrastructure can promote the unitary and centralized development of urban agglomeration spatial structure.(4)In the mechanism test,it is found that transport infrastructure affects the level of urban agglomeration by changing the functional connections of cities in urban agglomerations,and then affects the urban spatial pattern.The concrete empirical results show that in the eastern urban agglomeration,the improvement of transportation infrastructure can make the passenger and cargo volume dispersed among cities.In the central urban agglomeration,the improvement of transportation infrastructure mainly strengthens the economic ties between big cities and other small and medium-sized cities.Based on the above research conclusions,this paper puts forward several policy suggestions,such as promoting the construction of urban agglomeration according to local conditions,strengthening the division of labor and connection between large and small cities by using transportation infrastructure,and realizing the effective allocation of resources by utilizing various levels of transportation system.