Assessing the impact of Multifunctional Nature-Based Solutions for Climate-Resilient Bus Rapid Transit Systems in the Ahmedabad city, India

Extreme heat has become one of the deadliest climate risks worldwide, responsible for more annual fatalities than any other weather-related hazard (WHO; IPCC AR6). In rapidly urbanizing regions, urban heat island intensification can elevate local temperatures by 3–7°C, amplifying heat stress for millions of residents who depend on public transport for daily mobility. Cities in South Asia are projected to experience up to 75 days per year of “dangerous heat” (>40°C) by 2030, disproportionately increasing exposure for commuters who spend repeated periods in high radiation, confined, and paved microenvironments within transit infrastructure. Ahmedabad, one of the densely populated city of the world, exemplifies this rising risk, with 162 BRTS stations serving over 150,000 commuters every day—a population segment that is highly exposed yet poorly protected from escalating heat extremes. Assessing and improving the thermal safety of such public transport environments is therefore critical for advancing climate-resilient mobility, especially in Global South cities witnessing accelerated warming.

With this background, this study evaluates high-footfall transit nodes as priority urban adaptation sites, where Nature-Based Solutions (NBS) can simultaneously improve commuter health, support modal shift, and enhance sustainability outcomes. Using ENVI-met microclimate modelling, the thermal-comfort performance of 12 NBS strategies—including green roofs, green walls, hedges, and trees—was assessed individually and in synergy under peak summer boundary conditions. Results demonstrate that standalone elements offer limited reductions in ambient temperature (≤0.55°C) and smaller cooling footprints (~1,650–1,959 m²), whereas hybrid strategies achieve up to 1.93°C cooling with expanded influence areas exceeding 4,180–4,191 m². These spatial and temporal cooling gains translate into substantial reductions in hours of strong and very strong heat stress (UTCI), directly benefitting pedestrian-level comfort and heat-health protection.

Beyond climatic advantages, better shade and vegetation maintain optimum airflow conditions, suggesting decreased pollutant stagnation risk, hence enabling healthier waiting environments. NBS-integrated BRT stations can boost ridership, decrease heat-driven out-migration to private cars, and ultimately reduce transport-sector emissions by improving passenger comfort, so strengthening climate mitigation. Preliminary economic reasoning reveals great cost–benefit potential: relatively low-investment green aspects generate long-term benefits through decreased health burdens, reduced cooling energy demands in surrounding structures, improved fare revenues, and avoided infrastructure retrofits. This research offers a quantitative urban-climate decision-support system that lets municipal officials pick BRT stations for targeted NbS deployment based on microclimate exposure, cooling efficacy, and human heat-risk reduction. The method improves urban climate services for public transport planning in rapid warming areas by incorporating modeling outputs into practical station-design methods. The results provide scalable insights to encourage modal transitions, improve commuter resilience, and direct policy for climate-resilient transportation networks throughout megacities in the Global South.         

Keywords: Nature-based Solutions, ENVI-met, micro-climate Modelling, Urban heat mitigation