Urban rail transit, economic activity, and land development: A spatial difference-in-differences analysis of the Bangkok Metropolitan Region

Source abstract

Urban rail transit (URT) systems are widely promoted as instruments for improving urban mobility, stimulating local economic activity, and encouraging sustainable urban land development. However, empirical evidence on whether transit investments simultaneously promote both economic growth and land development remains limited, particularly in rapidly urbanizing cities where supporting land-use policies may be weak. This study examines the impacts of the Purple Line in the Bangkok Metropolitan Region (BMR), Thailand, on local economic activity and land development. Using satellite-based indicators, including Nighttime Light (NTL) and the Normalized Difference Vegetation Index (NDVI), as proxies for economic activity and land conversion, the analysis applies a spatial difference-in-differences (SDID) approach to identify causal effects while accounting for spatial spillovers. The results show that the introduction of the URT significantly increased local economic activity, with both direct and indirect spillover effects across neighboring areas. In contrast, land development near stations progressed more slowly relative to areas farther away, suggesting that improved accessibility alone does not necessarily accelerate physical development. These findings imply that land market dynamics, regulatory constraints, and speculative behavior may delay development responses following transit investments. Heterogeneity analysis further reveals stronger economic responses in initially underdeveloped areas. The study contributes to the literature by jointly evaluating economic and land development outcomes using SDID methods and satellite data. The results highlight the importance of integrating transportation investment with supportive land-use policies to ensure that accessibility improvements translate into sustainable urban development.