Optimizing Tunnel Design: CO2 & Cost Comparison of Steel Fiber vs. Steel Rebar Reinforced Shotcrete for Cham Road Bypass

The planned road bypass for the city of Cham in the Canton of Zug, Switzerland, includes a 400-meter tunnel constructed using conventional tunnelling methods, set to commence in late 2024. In response to a contractor's request, this study evaluates an alternative tunnel lining method, comparing the environmental impact of primary linings using steel fibre shotcrete versus the traditional steel rebar reinforced shotcrete. By quantifying the materials used and calculating the CO2 equivalents for both construction methods, this research aims to determine the potential for CO2 reduction. The analysis juxtaposes the environmental benefits with the associated costs, seeking to establish whether the adoption of steel fibre reinforced shotcrete not only reduces carbon emissions but also offers economic advantages. Results indicate that optimising tunnel cross-section design can reduce CO2 emissions, a potential finding with implications for the scalability of such designs in larger infrastructure projects. This study underscores the importance of innovative design in minimising the carbon footprint of tunnelling operations, leading to environmental benefits in the construction industry.