Does the clusters of high-speed railway network match the urban agglomerations? A case study in China

High-speed railways play a crucial role in intercity transportation, shaping the spatial interactions within urban agglomerations. However, a mismatch between transportation clusters and the spatial structure of urban agglomerations hampers regional economic integration. To address this issue, this paper proposes a community classification model, employing the Louvain algorithm, to analyze the aggregation of high-speed railway networks (HSRN). It compares central cities in city clusters with HSRN communities in relevant areas, examining the influence of central cities on urban agglomerations. The model is applied to a case study of China's high-speed railway network. The community classifications of HSRN are then compared with planned or future urban agglomerations at the national, provincial, and civic levels. The findings reveal that HSRN in China exhibits distinct clusters that align with the distribution of urban agglomerations. The existing central cities within these agglomerations provide good service levels in the HSRN network. However, HSRN communities within each urban agglomeration are overly scattered and should be integrated to reduce accessibility inequalities. This study offers suggestions for the development planning of HSRN and contributes to the economic integration of urban agglomerations.