Estimating life-cycle CO2 emissions of urban road corridor construction: A case study in Xi’an, China

Abstract

The carbon dioxide (CO2) emissions characteristics of urban roads together with the corridors’ municipal construction subprojects, such as drainage, water supply, power pipeline and illumination, are important for estimating the CO2 emissions for urban transportation. This paper aims to analyze the differences in the CO2 emission characteristics of one typical construction of Chinese urban road corridor in which the structure, materials and technologies are different with other published cases, to identify the important factors of the CO2 emissions and to provide some improving administration suggestions for the research type road. Choosing an example, which is the main urban road (Qinling) reconstruction project in Xi’an city, the documents of construction organization and the design budget estimation of the road are obtained, collected the construction process, machinery type and work time, and transportation distance as three type engineering quantities from five subprojects. Furthermore, the life-cycle assessment (LCA) and uncertainty analysis were applied for Qinling road corridor. The results are: (1) The CO2 emissions of the road subproject accounts for 53.19% of the whole corridor; (2) The CO2 emissions of the lime-fly ash, cement and lime accounts for 26.86%, 19.59%, 15.3% of the whole corridor respectively; (3) The CO2 emissions of on-site transportation, earth work, road building, hoisting accounts for 4.94%, 2.07%, 1.47%, 0.74% of the whole corridor, respectively; (4) The greater CO2 emissions coefficient of elasticity are from the production of lime, cement and asphalt concrete, which is 0.436, 0.134 and 0.125, respectively; (5) Compared with Route 35 reconstruction in New Jersey, the CO2 emissions of Qinling road corridor is 41.5 kg/m2 higher because of the important role of lime-fly ash base layer. To conclusion, important strategies are to decrease the emissions of production of lime and cement, to controll the ineffiecient movement of machinery, and to adopt cleaner materials in the base layer.