Activity-based carbon emission analysis of flexible pavement construction in Indonesia

The construction industry is a significant contributor to global greenhouse gas emissions, primarily through energy-intensive activities during the construction phase. This study investigated the carbon dioxide emissions associated with flexible road pavements by comparing activity- and cost-based calculation methods. The activity-based approach incorporates detailed equipment activity data, considering variations in equipment conditions, whereas the cost-based method relies on generalised emission factors linked to project costs. The results revealed significant discrepancies between the two methods, with the activity-based approach reporting substantially higher emission values. For example, the emissions for the wearing course (AC-WC) layer were 6 659 kgCO₂ for activity-based calculations compared to only 443 kgCO₂ for cost-based estimates. Such underestimations by the cost-based method demonstrate its inadequacy in accurately capturing construction emissions. Furthermore, the cement-treated base layer was identified as the largest contributor to emissions in activity-based analyses, contradicting the cost-based method’s attribution of the highest emissions to the AC-Base layer. This study emphasises the importance of using activity-based approaches for carbon accounting in road construction to ensure accurate assessments and inform sustainable construction practices. Policymakers are encouraged to adopt region-specific, activity-based methods to enhance carbon accounting accuracy and guide effective environmental policies for road construction.