Embodied carbon assessment of asphalt concrete roads and integrated drainage systems in Thai housing estates: a case study

This study quantifies the embodied carbon associated with the construction of asphalt concrete roads and integrated drainage systems commonly used in Thai housing estate developments. Using a case study approach, the research involved detailed data collection and analysis of work quantities, construction activities, and resource use, with emission factors primarily derived from Thai databases to ensure contextual relevance. The assessment applied a life cycle assessment (LCA) framework in accordance with BS EN 15978:2011, covering Modules A1–A5 (from raw material supply to on-site construction). The case study project—a 307 m asphalt concrete road with a 6.70 m carriageway and an integrated drainage system of equal length—generated total embodied carbon emissions of 198,466.532 kgCO 2 e, equivalent to 646.471 kgCO 2 e per meter of road. These values can serve as benchmarks for the Thai construction industry to support design decisions and construction control aimed at reducing environmental impacts. Work package-level analysis identified asphalt pavement laying as the dominant emission source, accounting for over 70% of total emissions, while concrete-related work packages—including gutter concrete, lean concrete for reinforced concrete (RC) pipes, manhole concrete, and RC pipe installation—collectively contributed nearly 21%. Overall, emissions were dominated by resource production and transportation (95.48%), whereas on-site construction activities accounted for a comparatively small share. Asphalt and ready-mixed concrete were the most influential materials due to their high emission factors and large quantities used. The findings provide practical insights to help stakeholders prioritize and implement effective embodied carbon reduction strategies in future housing estate infrastructure projects.