Unveiling spatial heterogeneity in urban underground space development patterns and mechanisms for differentiated planning: A points of interest-based study of Shanghai

Urban underground space (UUS) is crucial for sustainable urban development in high-density megacities. However, a comprehensive understanding of its spatial patterns and development mechanisms is still lacking. This study overcame UUS data limitations by employing points of interest to conduct municipality-wide analysis of Shanghai at the sub-district level. UUS spatial patterns and their driving mechanisms in the main city and suburbs were separately examined to unveil the spatial heterogeneity. Kernel density analysis showed a strong correlation between UUS clusters and urban public activity centers or metro systems. Distinct differences in UUS distribution were observed between the main city and suburbs, especially for underground parking and public service facilities. All tested underground spaces exhibited significant spatial autocorrelation. Geographical detector analysis identified significant driving forces of socio-economic conditions, land use, and urban location on UUS development. However, the benchmark land price, reflecting urban land scarcity, was the major factor to promote UUS development in the main city. In contrast, it exhibited the lowest driving force in the suburbs, which primarily served as an ancillary functional space for surface buildings. To improve UUS development quality, differentiated planning policies should be implemented in the main city and the suburbs. Research findings can provide insights for higher efficiency of UUS utilization and more effective planning policies in global megacities.