Reduction of CO2 emissions in tunnelling based on life cycle assessment

Abstract

Major tunnelling projects, like the extension of corridors for railway lines or the construction of large underground research facilities, are flagships in the European civil engineering industry. In order to deal with matters of sustainability and material management, as much of the generated excavation material must be reused – preferably directly on the construction site to avoid CO₂ emissions from long transport routes. While tools for quantifying the process-relevant carbon footprint are already available in other industry sectors, there is still no generally recognized method in the civil engineering and tunnelling industry, as every construction site has its own unique requirements. To find the best utilization option with the lowest possible carbon footprint, a life cycle assessment (LCA) is conducted, where the whole process is divided into three steps: use of construction equipment, transport, and landfilling/recycling of the excavation material. Finally, a ‘reference scenario’ for each process is determined and compared with optimized scenarios to calculate the potential of saved emissions.