InfraStructures - October 2010 - Giant TBM Finds its Way to Switzerland

Giant TBM Finds its Way to Switzerland

After having completed the contract for a tunnel boring machine (TBM) of 8 m diameter in December 2009, and following an optimal workshop acceptance, the various individual parts of its latest tunnel boring machine left Aker Wirth’s plant in Erkelenz, Germany, in July. The components were delivered to Switzerland where a tunnel is to be bored for the extension of a hydroelectric power plant.

Before the delivery the machine was put through its paces during the course of a comprehensive test program at Aker Wirth’s plant: the basic functions were checked and the 4000 hp main drive was submitted to a 24-hour endurance test.

The company’s end-to-end, professional quality assurance system is highly appreciated and valued by construction companies and project owners.

By the beginning of August all the components had been transported to the construction site in Tierfehd in the Swiss Canton of Glarus, directly on the way up to the Klausenpass (approximately 80 km south of Zürich). On the jobsite the machine had to be reassembled and was scheduled to start drilling in the middle of October 2010. The machine is to bore a 4 km access tunnel to the underground cavern which houses the machines for the new pumped storage power plant in Limmern.

The tunnel has a diameter of 8,03 m and goes up from 800 m (above sea level) to about 1700 m at a constant gradient of 24%. For this inclined tunnelling the Aker Wirth TBM has been equipped with additional securing fixtures to cope with rising gradients. Up until now rising inclined tunnelling has only been carried out by machines up to a diameter of 6 m.

The tunnelling of the Limmern access tunnel will therefore be the largest inclined operation of this kind to have ever been carried out with a tunnel boring machine.

The extension of the existing production facility of the Kraftwerke Linth-Limmmern AG with the new pumped storage plant is an important project for Switzerland’s future electricity supply. The order for the tunnel boring machine was placed with Aker Wirth by ARGE Zugangsstollen Limmern who will carry out the construction of the tunnel. This consortium consists of the companies Rothpletz, Lienhard + Cie AG, Baresel GmbH, Wayss & Freytag Ingenieurbau AG, G. Lazzarini & Co. AG, Andrea Pitsch AG and Ragotti+Weber Bau AG.

Source: Aker Wirth GmbH