Impact of Metro Line Infrastructure Along the Urban Canyon on Urban Heat Island Effect in Chennai

Abstract

Urban Heat Island (UHI) effects are a growing concern in rapidly urbanizing cities like Chennai, India. UHI is characterized by elevated temperatures in urban areas compared to their rural surroundings, driven by changes in land use, reduced vegetation, and increased impervious surfaces. As Chennai undergoes significant infrastructural expansion, including the development of elevated metro corridors, understanding the interplay between urban morphology and UHI becomes critical for sustainable city planning. This study examines the impacts of elevated metro-line infrastructure on UHI dynamics in Chennai, employing a multi-modal methodology that integrates remote sensing, field data logging, and simulations. Chennai s urban transformation has introduced elevated metro corridors within urban canopies, altering heat absorption, reflection, and airflow dynamics. While the metro network enhances connectivity, its extensive concrete structures contribute to unique thermal patterns. Despite studies addressing the role of vegetation and urban morphology in UHI mitigation, the specific impacts of elevated metro infrastructure on UHI have received limited attention. This study employs a multi-modal approach to investigate the impact of Chennai s elevated metro-line on the Urban Heat Island (UHI) phenomenon, specifically focusing on Surface UHI Intensity (SUHII) and Atmospheric UHI Intensity (AUHII). The research spans the Chennai Metropolitan Area (1,189 km²), concentrating on the 27.03 km elevated metro corridors due to their potential interaction with urban microclimates. Remote sensing analysis was conducted to understand overall UHI scenario in Chennai and identify UHI hotspots and cool spots, highlighting the metro-line corridor as a significant area of interest. Remote sensing data from 2006 and 2022 were compared. Since metro approval occurred in 2007, 2006 was selected as the baseline year, representing conditions without metro infrastructure or related activities, while 2022 reflects the most recent impacts. This i