Abstract: In the context of the "dual carbon" strategy, carbon emission reduction during the road maintenance phase has become a key breakthrough for the green transformation of transportation infrastructure. For a long time, traditional road maintenance methods have relied excessively on the extraction of new materials and high-temperature mixing, which not only exacerbates resource consumption but also brings about persistent high energy consumption, high emissions, traffic congestion, and noise nuisance caused by road construction, leading to increasingly prominent environmental and social pressures. Based on this, this paper relies on real-world engineering projects and relevant literature data, employs the Life Cycle Assessment (LCA) analysis method, constructs a three-stage boundary of "on-site construction - production - transportation", simultaneously quantifies the energy consumption and carbon emissions per unit area of on-site warm mix recycling technology, on-site hot recycling technology, and traditional milling and repaving, and couples with a traffic interference model to assess their indirect effects. The results show that the energy consumption of on-site warm mix recycling is about 2.89 kgce/m², and the carbon emissions are about 5.40 kgCO₂e/m². The energy consumption of on-site hot mix recycling is about 3.06 kgce/m², and the carbon emissions are about 5.67 kgCO₂e/m². Compared with traditional milling and repaving, these technologies achieve energy savings and emission reductions of about 67.97% and 72.85%, 66.02% and 71.53%, respectively. Thus, it can be seen that the on-site warm mix recycling maintenance technology has the best energy-saving and emission-reduction effect. Considering the indirect energy-saving and emission-reduction effects of congestion, the comprehensive carbon emission reduction rate of on-site warm mix recycling maintenance technology can exceed 80%. This road maintenance technology does not require traffic closure, has a high utilization rate of old materials, and combines environmental, social, and economic benefits. It can provide a quantitative basis for road maintenance carbon budget and carbon trading, and has broad promotion prospects. The research conclusion provides a reproducible and scalable evaluation framework for the industry's low-carbon decision-making, which is of great significance for promoting green highway construction and achieving the goal of carbon neutrality in the transportation sector.