New Life for Karahnjukar TBM at Ceneri Base TunnelTBM #1 that achieved successfully its task on the main headrace tunnel of the Kárahnjúkar hydropower project in Iceland will be the first Robbins machine to bore on one of Europe's largest tunnelling projects in recent memory. The machine will bore a 2.4 km-long adit tunnel on the Ceneri base tunnel project in Switzerland. The new tunnel is part of the much larger AlpTransit project and will connect with the 57 km-long Gotthard base tunnel. The contract was signed in June with Consorzio Monte Ceneri (CMC), a consortium of CSC, Frutiger, and Rothpletz, Lienhard & Cie. Click here. Visit www.therobbinscompany.comThe main beam TBM will be completely refurbished near Milan, Italy and the cutterhead diameter will be increased from 7.6 m to 9.73 m. The cutterhead will be the first on the AlpTransit project to utilize larger diameter 48.3 cm cutters. Located in Switzerland's Ticino canton, the adit tunnel will join up at approximately the halfway point of two parallel main rail tunnels. Rock in the area consists of schist, Swiss molasse, and Ceneri orthogneiss with a UCS of 30 to 130 MPa. The geology is expected to be good for TBM boring, with no squeezing ground or large water inflows anticipated. New probe drills, being designed by Robbins in its US locations, will be used to verify ground conditions ahead of the TBM. Temporary tunnel support including rock bolts, ring beams and shotcrete will be used depending on geology. Excavated material will be temporarily stored at a lot onsite for later preparation as rock aggregate for concrete. Utilizing the latest in disc cutter design, the Robbins machine will bore through geology similar to that found in the Gotthard base tunnel, which used 17-inch back-loading disc cutters. Larger diameter 48.3 cm back-loading disc cutters, first pioneered at the Kárahnjúkar hydroelectric project, offer a higher cutter load and longer cutter life than the 43 cm design, resulting in fewer cutter changes. Tunnelling using the Robbins TBM is scheduled to begin in autumn 2008 and will take about two years to complete. The Ceneri base tunnel project will involve construction of twin 15.4 km-long main rail tunnels running in north and south directions for owners AlpTransit. The tunnels are part of AlpTransit's massive project to provide more efficient rail freight routes via base tunnels through the Gotthard and Ceneri mountain ranges. Currently, freight trains travelling up the mountain ranges require pushing locomotives due to steep gradients. The base tunnels will provide a route for freight trains with minimum elevation gain and will shorten passenger train times between Zurich and Milan. Some route times, such as the trip between Lugano and Bellinzona, will be cut in half with the completion of the Ceneri tunnel. Tender documents for the Ceneri base tunnel main contracts are currently being prepared. The contract will include two 8 km sections of drill-and-blast tunnels for the north running main line, while the south running line will include two 1.8 km sections of drill-and-blast and two 4 km sections of TBM-driven tunnels. The completed rail line is expected to open to traffic in 2019. Click ch/14. Visit www.alptransit.ch 37/07. Installation caverns will be used as TBM launch sites and underground concrete batching plants for the Ceneri Base Tunnel in Switzerland. A 9.73 m Robbins TBM will bore a 2.4 km adit tunnel, similar to the exploratory bore seen here