A Hybrid Drainage, Normal and Storm water Management, and Operational Pump-Out Framework for Mitigating Road Water logging and Traffic Congestion in Megacities- Evidence from Dhaka

Road waterlogging during the monsoon season remains a critical urban infrastructure challenge in Dhaka City, Bangladesh, where short-duration, high-intensity rainfall frequently overwhelms the existing stormwater drainage system. Dhaka receives approximately 2,000–2,200 mm of annual rainfall, with peak monsoon intensities commonly exceeding 50–100 mm/h—levels that surpass the effective capacity of conventional roadside drains and box culverts under current urban conditions. Although extensive drainage infrastructure exists, system performance is severely constrained by flat topography, tidal and backwater effects at outfalls, widespread drain blockage, encroachment of natural canals, and the absence of intermediate stormwater storage. As a result, gravity-based drainage systems fail to provide timely surface water removal, leading to prolonged road inundation, severe traffic congestion, accelerated pavement deterioration, and significant economic losses. This paper proposes a hybrid stormwater management framework that integrates closed underground box drains, decentralized stormwater detention tanks, controlled discharge mechanisms with backflow prevention, and operational night-time pump-out using municipal pump trucks. The proposed system shifts the drainage paradigm from immediate conveyance to a store–delay–remove strategy, whereby excess runoff generated during peak rainfall is temporarily detained to prevent surface flooding and subsequently evacuated during off-peak hours when hydraulic and traffic conditions are favorable. Unlike conventional permanent pumping stations, the framework emphasizes decentralization, operational flexibility, reduced energy dependence, and scalability for dense urban environments. A conceptual engineering assessment based on representative Dhaka City road catchments indicates that modular detention units with capacities on the order of 30,000–50,000 liters can significantly reduce surface water accumulation during critical rainfall durations of 30–45 minutes. By limiting roadway inundation depth and duration, the proposed system directly improves traffic mobility, maintains emergency access, and enhances overall urban resilience during monsoon events. The study demonstrates that integrating physical drainage infrastructure with operational stormwater management provides a practical, cost-effective, and context-appropriate solution for mitigating road waterlogging and traffic congestion in monsoon-affected megacities such as Dhaka. Please check the attachment for details