Flood-induced effects on vehicular traffic in Metro Manila, Philippines

In Metro Manila, recurrent flood-related issues significantly disrupt transportation infrastructure, even with minimal rainfall. Existing models rely on assumptions and theoretical values for key traffic flow parameters, leaving a gap in understanding the effects of flooding based on real-world traffic conditions. This study aimed to investigate the impact of flooding on vehicle movement in Metro Manila. Fifteen 30-minute video clips of flooded roads from Metro Manila Development Authority’s (MMDA) close circuit cameras’ archive were analyzed. The results show that increased flood depth strongly correlates with reduced vehicle volume demand. Additionally, lane closures exacerbate this reduction, with more closures leading to greater disparities in vehicle flow. Moreover, a new polynomial function was introduced to represent the relationship between flood depth and vehicle speed, reflecting lower average speeds than previous models. Lastly, flood depths over 25 cm consistently caused lane closures, leading to a significant reduction in vehicle flow, which decreased by 40–70% per lane kilometer as lane closures increased. Overall, this research advances the understanding and mitigation of urban flooding impacts on transportation systems. Integrating these empirical findings into future flood-based traffic models will enable urban planners and policymakers to develop more robust and context-specific strategies for mitigating the impacts of urban flooding on transportation networks.