Global warming potentials due to railway tunnel construction and maintenance

Abstract

Global warming is a critical issue nowadays. Although the railway system is considered as green transportation, it cannot be denied that railway tunnels have a significant environmental impact during construction and maintenance. At the same time, asset management of a project becomes more popular in project analysis. Therefore, this study aims to analyse life-cycle cost (LCC) and life-cycle assessment (LCA) for the Xikema No. 1 high-speed railway tunnel in China to consider the environmental impact of rail tunnel construction. The initial capital costs of tunnel and rail construction, operation, and maintenance costs have been separately considered in terms of the life-cycle cost analysis and net present value (NPV) with various discount rates. The LCA analysis has presented the CO2 emissions and energy consumption over the construction and operation processes into consideration. The CO2 emissions and energy consumption caused by material production, maintenance, and material transportation have been accounted for. The results show that the materials used during the construction process contribute to about 97.1% of CO2 emissions of the life-cycle while CO2 emissions caused by the operation and maintenance process are relatively small compared with the construction process. Moreover, the maintenance process consumes over 55% of the life-cycle energy. The energy consumption of the tunnel construction process is approximately 44.3%. At the same time, the construction contributes to the main proportion of LCC due to relatively low cost in the operation and maintenance stages.