Environmental impact assessment and normalization of different expressway sub-projects during construction

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 in normalized methods. 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, which is mostly associated with a few types of construction materials, contributed the largest proportion (approximately 90%) of the life cycle environmental impact. Cement, explosives, and wood contributed significantly to global warming potential, substance of ozone depletion, and land use contributing 51.55%, 70.87%, and 54.95%, respectively, in the subgrade sub-project. The environmental impact ratio can indicate the degree of matching between the environmental impact of a material and its preparation technologies. When the environmental impact ratio is high, 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.