Assessment of CO2 Emissions from Asphalt Pavement Maintenance Using a Life-Cycle Perspective: A Case Study of the Mexicali–San Felipe Highway

Maintaining asphalt pavements requires substantial quantities of materials and energy, which significantly contribute to greenhouse gas emissions in the road infrastructure sector. This study quantified the carbon dioxide equivalent (CO2e) emissions associated with a maintenance and rehabilitation plan for an asphalt pavement using a simplified life-cycle perspective integrated with the Highway Development and Management Model (HDM-4). The methodology combined HDM-4 to define a 35-year intervention plan (2022–2057) with CO2e emission factors for three quantified components: material production, transportation, and construction machinery operation. The approach was applied to a 7.8 km section of the Mexicali–San Felipe highway in Baja California, Mexico. The results indicate that the intervention plan generated approximately 2483.9 t CO2e over the 35-year analysis period. Reconstruction was the most carbon-intensive activity, accounting for 1890 t CO2e, while milling and overlay generated 292.15 t CO2e per direction. Material extraction and production were the dominant sources of emissions, contributing about 70% of the total emissions in milling and overlay and 60% in reconstruction; in the latter case, transportation also represented a substantial share (35%) due to long haul distances. These findings show that the proposed approach can identify the most emission-intensive activities and processes within pavement maintenance plans and provide quantitative environmental criteria to support more sustainable road management decisions.