Environmental economic profiles of expressway construction via life cycle assessment

Abstract

The construction process of expressway is characterized by high energy and materials consumption, which poses overwhelming potential threat to the physical environment. In order to coordinate contradiction between expressway construction and concomitant environment issues, this study quantitatively assessed environmental impact of different sub-projects and presented an environmental price model to characterize the overall environmental impact of construction materials. The results showed that the bridge, culvert, and tunnel sub-projects produced the most significant environmental impact. Compared with onsite construction and transportation, material production contributed the largest proportion (approximately 90%) of the life cycle environmental impact. Most of the environmental burdens were only associated with a few types of materials (e.g., steel, iron, and cement). Steel, in particular, contributed to 29.73%–80.47% in the four categories of environmental impact (including global warming potential (GWP), fine particulate matter production (FPMF), terrestrial acidification (TA), and ozone formation health (OF-H) in four sub-projects (including bridge and culvert, tunnel, safety measures and embedded pipelines (SMEP), and green and environmental protection facilities (GEPF)).Notably, certain materials contributed significantly to only specific environmental impact categories of environmental impact. Cement, wood, and explosives contributed significantly to GWP, land use (LU), and substance of ozone depletion (SOD)contributing 51.55%, 70.87%, and 54.95%, respectively. Environmental impact ratio can indicate the matching degree between the environmental impact of a material and its production process. For some materials with high environmental impact ratio, such as iron, brick and cement, a focus on green update and iteration of production technologies of such construction materials are required. This study identifies the environmentally sensitive links of different expressway construction sub-projects and provides a decision-making basis for the selection of construction materials and upgradation and iteration of production technologies from the perspective of environmental price, thus providing scientific guidance to green expressway construction.