ABSTRACT
Carbon dioxide emission plays a crucial role in climate change, and the construction industry is considered as one of the major contributors. With the growth of urbanization, many underground infrastructures, such as metro tunnels, are being constructed to solve traffic problems and expand urban usable space. However, the carbon emission over the full life cycle of tunnels has been rarely studied. This study assesses the life cycle carbon emissions of tunnel infrastructure, presenting a detailed analysis of carbon emission sources and further proposes a calculation framework for quantifying life cycle emission, which is subsequently implemented in a case study of a metro tunnel project. The results of the case study show that material use is the primary source of emissions during construction, contributing about 83% of the emissions in this phase, while emissions during the operational phase can account for up to 90% of the tunnel’s full life cycle emissions if the metro train operation is considered. The paper then proposes several measures to reduce carbon emissions, contributing toward the sustainable and green development of tunnels.
