Visualizing Cradle-to-Gate Carbon Emissions in Pavement Construction: A Case Study

The road sector, as an important contributor to China’s greenhouse gas emissions, needs to take urgent actions to assess the environmental impacts and provide recommendations for emissions reduction. To this end, a cradle-to-gate life cycle assessment (LCA) approach is employed to examine the environmental impacts, focusing on global warming potential (GWP), of a real expressway construction project in Xuzhou, Jiangsu Province, China in this study. The amount of material, energy, and their corresponding carbon emissions in different phases are visualized using an improved Sankey diagram. In addition, sensitivity analyses are performed to identify sensitive factors that significantly impact GWP. It is found that the raw material production phase produces the greatest carbon emissions (about 84%). The construction phase accounts for 13%, and the transportation phase provides an insignificant contribution (approximately 3%). The bridge part of the project contributes significantly to carbon emissions because of the use of cement and steel. Therefore, road design should optimize alignment to avoid the construction of bridges to minimize cradle-to-gate carbon emissions.