How do urban spatial structures evolution in the high-speed rail era? Case study of Yangtze River Delta, China

The construction of high-speed rail (HSR) networks is of great significance to researchers in the fields of regional development, regional structure, and regional integration. Whilst a large number of studies have estimated the impacts of HSR networks on regional economic development, accessibility, and commuting behavior, how urban spatial structures evolution in the HSR era remain largely unexplored. Thus, the purpose of this paper is to explore how the urban structures (urban hierarchical structure and urban physical structure) of cities in the Yangtze River Delta evolution by employing a reverse gravity model and a gravity deviation model in the HSR era. Our findings indicate that in the HSR network, the traffic attractiveness of cities in Pan-Yangtze River Delta showed an obvious hierarchical distribution (taking on a spindle shape), and that the first-tier cities comprised of Shanghai and Nanjing. We further found that the impacts of introducing a HSR network on urban land growth were greater in non-HSR cities than in cities with HSR. In addition, the growth rate of urban land was found to be higher in areas surrounding HSR stations than in the city at large. This shows that the introduction of HSR significantly stimulated the development of the cities making up the study area. More importantly, after the opening of the HSR network, the center of gravity of the urban areas of 75% cities that were connected to the HSR network was found to deviate towards the HSR station. Differences in the pattern and degree of deviation were identified, thus indicating the presence of individual differences in the effects of HSR on urban growth in different cities.