An 8m diameter Aker Wirth hard rock TBM is currently being transported from the company’s plant in Erkelenz, on route to Klausenpass, some 80km south of Zürich, where it will be assembled and prepared to start work in October on a 4km long hydropower access tunnel.
The access tunnel, to a new underground pumped storage power plant, will be constructed by “ARGE Zugangsstollen Limmern” (AZL), which consists of the companies Rothpletz, Lienhard + Cie AG, Aarau (Switzerland), Baresel GmbH, Stuttgart (Germany), Wayss & Freytag, Frankfurt (Germany), G. Lazzarini & Co.AG, Chur (Switzerland), Andrea Pitsch AG, Thusis (Switzerland) and Ragotti+Weber Bau AG, Nestal (Switzerland). The tunnel rises on an incline from 800m asl to about 1700m at a constant gradient of 24%. For this inclined tunnel boring the TBM has been equipped with additional securing fixtures to cope with the upward gradient. Until now rising inclined tunnels have only been bored by machines of diameters up to 6m. The tunnelling of the Limmern access tunnel will therefore be the largest inclined operation of this kind to be carried out using a TBM.
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The extension of the existing production facility belonging to the client, the Kraftwerke Linth-Limmern AG, is an important project for Switzerland’s future electricity supply and is being constructed to meet the increasing demand for power in the local area.