The impact mechanism of high-speed rail accessibility on urban expansion in China: An analysis based on the mediating effect model

As a new means of high-speed transportation, high-speed rail(HSR) has an important impact on the scale of urban land use in Chinese cities. Exploring the impact mechanism of HSR accessibility on urban expansion is of certain significance for urban land use planning and management in the era of HSR network development. This paper constructs a national HSR network, interprets multi-dimensional accessibility from the HSR network with the help of complex network methods, and uses the mediating effect model to explore the impact mechanism of HSR accessibility on urban expansion. The results show that (1) Closeness centrality, betweenness centrality, degree, weighted degree and the number of HSR frequency stopped all promote urban expansion by stimulating investment in real estate development, total retail sales of consumer goods, employment density and the proportion of added value of the tertiary industry, and inhibit urban expansion by restraining the proportion of added value of the secondary industry. (2) When the total retail sales of consumer goods is used as the mediating variable, the promoting effect of betweenness centrality, degree, weighted degree and the number of HSR frequency stopped on urban expansion is the strongest through this mediating variable. When the proportion of added value of the tertiary industry is used as the mediating variable, the promoting effect of betweenness centrality, degree and weighted degree on urban expansion through this mediating variable is the weakest.