Assessing the potential of heat stress mitigation in asymmetrical street conditions of Bhopal city

Abstract

In Indian cities, where streets are the only affordable public space, thermal-climatic conditions have a significant impact on pedestrian activity and comfort. However, narratives are insufficient on pedestrian risk assessment in asymmetrical urban settings. Therefore, current study investigates the potential of thermal stress mitigation in the context of human biometeorological assessment in asymmetrical urban settings of Bhopal city. It initiates with the selection of a commercial street in tropical climate of Bhopal (Koppen climatic classification, Aw) with the measurement of its metrological and morphological attributes. Furthermore, it leads to an assessment of thermal stress utilizing physical survey and Envi-met simulations including the identification of critical spots. Finally, development of iterated scenario considering one major and local street with five varied street sections in symmetrical/asymmetrical condition for the EW, NWSE and NS orientation. The efficiency of mitigation measures in cooling the outdoor stress area was analysed by using Universal Thermal Climate Index (UTCI) along with mean radiant temperature (MRT) from a spatiotemporal perspective. The highest stress reduction was observed in higher asymmetrical section while lowest was recorded by lower symmetrical section. However, it is recommended to integrate high asymmetrical sections in complex urban area which can provide a better reduction (average UTCI by 3 °C, average MRT by 7 °C) to outdoor stress due to their ability of regulating efficient wind flow and shielding radiation. The evidence-based selection of street orientation and openness can adopt to optimize the urban configuration in similar climates to improve streetscape and activities from an environmental quality perspective.