Gotthard base tunnel: 1000 km of high quality seam welding for 57 Km tunnel
The Gotthard Base Tunnel is a railway tunnel through the Alps in Switzerland. With a route length of 57.09 km, it is the world's longest and the first flat, low-level route through the Alps. It is also the deepest railway tunnel in the world, with a maximum depth of 2,450 metres, comparable to that of the deepest mines on Earth. The construction began on 4 November 1999 and was completed in 2016.
AlpTransit Gotthard AG, a wholly owned subsidiary of the Swiss Federal Railways was responsible for the construction. The Gotthard Base Tunnel was constructed to increase local transport capacity through the Alpine barrier and more specifically to shift freight volumes from trucks to freight trains. This significantly reduced both the danger of fatal road crashes involving trucks, and the environmental damage caused by heavy trucks. Built over 17 years and costing around 11 billion Euros, the twin-bore tunnel has won the 2018 European Railway Award. It has been officially recognised as an “outstanding example of shifting freight transport to more environmentally friendly modes of transport.”
Leister Technologies AG was chosen for this project not only because the Swiss company is the leading supplier of plastic welding solutions, enjoying an excellent international reputation; the geomembrane manufacturer also chose it based on the company's more than 60 years of positive experience.
More than 1000 kilometres of high quality seam welding was done with Leister machines to complete the twin bore 57 km long tunnel. Leister TWINNY S automatic welding machines and hot air hand tools were used for this mammoth task. The compact combination wedge device of TWINNY S proved its merits once more even with overhead welding as the TWINNY S presses the two sheets together and thus rises easily and safely during welding. Despite its small dimensions, welding speeds of up to 6.5 ft per minute were possible with the TWINNY S. This was a crucial advantage considering the size of the project. The tightness is the most important criterion when evaluating the weld quality. To guarantee the greatest possible safety, a test channel was installed for each overlap weld. Regular peel tests to check the weld quality were carried out directly in the tunnel using the EXAMO test device from Leister, a device highly suitable for construction sites. Not only is the processing and the material crucial, but also the machinery used. “We work exclusively with Leister devices and depend on their reliability. They correspond exactly to our requirements. We have been working with Leister equipment for as long as I can remember...” said Mr. Urs Streuli, project manager of the material supplier who was in-charge of this project.
With a planned service life of over 100 years, only the best quality of material, processing and machine enables fault-free and hence efficient work. Leister proved once more that its products withstand all the demands placed on them, even when they are extreme.