Detecting the contribution of transport development to urban construction land expansion in the Beijing-Tianjin-Hebei region of China based on machine learning

Transport development is closely related to the urban-rural transition and urbanization, as manifested by the expansion of urban construction land. However, among the various driving factors of urban construction land expansion, the contribution of transport development has rarely been quantified. Using 200 county-level administrative regions in the Beijing-Tianjin-Hebei (BTH) region of China as the study area, this research analyzed the spatialtemporal patterns of transport dominance—measured by density, proximity, and accessibility—and urban construction land expansion, measured by total urban construction land area (ULA) and per capita urban construction land area (PCCLA) during 1995–2018. Then, exploratory spatial data analysis and the gradient boosting decision tree (GBDT) model were applied to investigate their spatial relationships and to quantify the contribution of transport development to urban construction land expansion. The results indicate that both ULA and PCCLA first increased and then decreased during the study period, with regional disparities among different counties narrowing, mainly due to reductions in urban construction land area in Beijing and Tianjin. Second, transport development exhibited significant positive spatial autocorrelation with urban construction land expansion, characterized primarily by ‘high-high” and “low-low” clustering patterns. Third, transport development played an important role in urban construction land expansion, with its contribution initially exceeding that of other socioeconomic and natural factors but declining as transport infrastructure matured. Finally, transport development exerted a nonlinear influence on urban construction land expansion. Among the three aspects of transport development, density had the most significant impact, followed by accessibility and proximity. The findings of this research provide useful insights for transport and land use planning in metropolitan regions of developing countries.