Wirth TBE Breaks Through First Uetliberg Tunnel in SwitzerlandWirth's Tunnel Bore Extender (TBE), an innovative tunnelling system, broke through the first bore of the Uetliberg tunnel on 1st February, 2005. The TBE has been at work on the first bore since 11th April, 2003. It is the largest diameter hard rock tunnelling machine of its kind in the world. To read how the TBE system works, visit www.wirth-europe.de/NEWS/Uetliberg.htmA pilot bore for ventilation and safety was first driven using a Wirth TBM (subscribe to E-News Weekly 24/2002) prior to being enlarged by the TBE, which opened a 14.4 m-wide x 14.2 m-high cross section (approximately 162 sq m) in hard molasse ground, which consists of alternating flat-bedded strata of hard sandstone and soft marl. The 180 m-long TBE will now be removed and transported to the Reppischtal shaft to drive the second tube. This is scheduled to begin in June 2005. The Uetliberg tunnel in Zurich consists of two 4.4 km-long parallel tubes, which both increase in slope by approximately 1.6% between the east and the west portals. Each tunnel has two lanes and a hard shoulder. The maximum overburden of the tunnels under the Uetliberg mountain is approximately 320 m.The project design and construction supervision has been commissioned to Amberg Engineering. The Uetli JV of builders is led by Zschokke Locher and also includes Murer, Prader, CSC, Wayss & Freytag, Alpine Mayreder Bau and Zueblin. Tunnelling is planned to be finished in 2007 for opening programmed for the autumn of 2008. The total cost of the project will reach CHF1 billion. Click ch/24. Visit www.uetlibergtunnel.ch, www.westumfahrung.ch and www.amberg.ch 08/05.