Analysis of structural evolution and its influencing factors of the high-speed railway network in China's three urban agglomerations

Development of HSR network has an important impact on the evolution of urban spatial structure. However, quantitative discussions on influencing factors of HSR network evolution are still lack. This study explores the structural evolution and influencing factors of HSR network consisting of three urban agglomerations. The main results are as follows: (1) The HSR network in Beijing-Tianjin-Hebei (BTH) had maintained a stable twin-city structure, while Yangtze River Delta (YRD) and Pearl River Delta (PRD) presented a balanced and polarized structure respectively. (2) The community structure of HSR network in BTH and YRD had become complex and diversified, while that in PRD was simple and stable. (3) The overall level of HSR connections in PRD has grown at the first and that in BTH has dropped at the bottom in 2019.The overall level of connectivity of HSR network in PRD continued to rise, and it continued to decline in YRD. That in PRD has significant small-world feature. (4) The interaction intensity of tourism, income, technology, and investment of cities significantly affects HSR network structure. This article helps to adjust HSR network structure from the demand of residents' travel be-tween cities, and optimize the service supply of inter-city high-speed travel.