Aker Wirth has been commissioned to construct and deliver a gripper tunnel boring machine (TBM) by the ARGE Zugangsstollen Limmern (AZL) consortium, which commissioned the Aker Wirth TBM and will realise construction of the gallery. The order has a total value of over €20m.

The AZL consortium consists of:

  • Rothpletz, Lienhard + Cie, Aarau (Switzerland)
  • Baresel, Stuttgart (Germany)
  • Wayss & Freytag, Frankfurt (Germany)
  • G Lazzarini, Chur (Switzerland)
  • Andrea Pitsch, Thusis (Switzerland)
  • Ragotti+Weber Bau, Netstal (Switzerland)

The machine will be used for the subterranean expansion of the Linth-Limmern power plant in Switzerland, boring approximately 4km from the access gallery to the new machine cavern.
The access gallery portal is near the village of Linthal in the Canton of Glarus, south of Zurich. The bore hole has a diameter of 8.03m and rises from 800m to approximately 1,800m above sea level with a constant gradient of 24%.

The Aker Wirth TBM has been equipped with additional safety fittings for the ascending tunnel to accomplish this inclined shaft borehole. Inclined shaft boreholes with diameters up to approximately 6M have been machined to date. Tunnelling of the Limmern access gallery currently represents the largest inclined shaft to be completed by a TBM.

“Aker Wirth’s TBMs have been successfully used in inclined shaft projects since the mid-1960s,” indicates CEO Christoph Kleuters. In 1967, the Erkelenz company entered the TBM market and one of the first hard rock TBMs was a special machine of this style designed for inclined shaft tunnelling. “Our customers can rely on over 40 years of experience that we have gathered in the construction of these machines,” says Kleuters.

For the purpose of this special task, the Aker Wirth TBM is connected with backup construction where material can be conveyed between the machine and portal, in addition to the securing and lining of the tunnel walls drilled. This system is constructed by the Swiss cooperation partner Rowa Tunnelling Logistics from Wangen, a company that Aker Wirth has collaborated successfully with for many years.

The machine will be completed by mid-2010. Construction will take place at the Erkelenz plant followed by an in-plant test run before being transported and assembled at the jobsite. Drilling of the headrace gallery will commence in the fourth quarter of 2010.

The extension of the Linth-Limmern pump storage power plant is a highly anticipated future project which aims to expand the harnessing of electrical energy from hydropower. This environmentally-friendly technique is an important method of generating performance and energy to continue its steady growth, expanding its position in the energy industry. After all, Copenhagen is not all that far away from Erkelenz.