Comparative Life Cycle Assessment of Road Construction and Operation: Evaluating Environmental Sustainability

This study applies the Life Cycle Assessment (LCA) to evaluate the environmental impacts of different types of road construction, including at-grade sections, trenches, embankments, viaducts, and tunnels. The functional unit used is 100 m, and system boundaries consider raw material extraction, transport, construction, and operation based on a 30-year lifetime. Impact categories considered are Global Warming Potential (GWP), Acidification Potential (AP), Eutrophication Potential (EP), Photochemical Ozone Creation Potential (POCP), and Human Toxicity Potential (HTP). Results show that tunnels generate the highest impacts during construction, particularly in terms of CO₂eq and SO₂eq, while operational impacts remain similar across all road types. A valuable consideration can be made on the "emissions equivalence" observed when the length of the at-grade road is approximately twice that of the tunnel, enhancing the importance of a "full view" of the impacts. In exploring mitigation strategies, the use of bottom ash from municipal solid waste incineration as an alternative material reduced GWP-related emissions by about 50%. While the existing literature tends to focus on individual types of infrastructure or specific materials, the following work proposes a systemic approach that links design choices to circular economy strategies, quantitatively demonstrating the potential for reducing environmental impacts using secondary materials.