Nonlinear effects of public transport accessibility on urban development: A case study of mountainous city

The increasing pace of urbanization has given rise to numerous challenges in urban areas, including limited land resources, severe traffic congestion, and environmental degradation. To address these issues, Transit-Oriented Development (TOD) has been identified as an effective strategy for promoting sustainable urban development by enhancing the link between transportation and land use. This study explores the nonlinear relationship between public-transport accessibility and urban development from the perspective of mountainous cities, using Chongqing, China as a case study. The gradient-boosting decision tree (GBDT) is employed to analyze nonlinear effects via big data and open data. The results of the study reveal that metro and street accessibility significantly impact urban development in Chongqing, while the effects of the central-business-district (CBD) and bus transportation are weaker compared to plain cities. Four metro stations in Chongqing are selected to examine the local effects of public-transport accessibility on urban development. This research sheds light on the accessibility and urban-development issues in mountainous cities, considering the influence of topographical factors.