Assessing the impact of pluvial flooding adaptation measures on urban transport in Bangkok

Urban pluvial flooding disrupts mobility by reducing road capacity and prolonging travel times, yet most assessments emphasize congestion without considering mode choice. This study develops an integrated framework that links flood simulation with a travel demand model to evaluate how inundation affects both congestion and mode shifts in Bangkok. Results show that flooding triggers a notable shift from car to rail, underscoring the importance of resilient transit systems. Improved drainage reduces flood severity but cannot fully resolve congestion, indicating that infrastructure upgrades alone are insufficient. Complementary transport policies are essential to sustain mobility under flood conditions. Among the strategies analyzed, expressway toll reductions improved accessibility but produced mixed outcomes, while rail fare discounts consistently encouraged shifts to flood-resilient modes. These findings highlight the dual role of engineering and behavioral measures in flood adaptation and provide transferable lessons for megacities facing climate risks.