Cutterhead assembly is underway in the launch shaft for the first Herrenknecht TBM that will drive in the Lower Inn Valley, Austria, as part of the northern rail access to the future Brenner base tunnel.
The 13m diameter Mixshield is scheduled to begin excavation by mid-June on a 5.835km bore on Lot 3-4 (Munster-Wiesing) of the project, T&TI was told by the client, Brenner Eisenbahn GmbH.
Previous tunnel construction work on the project means a tube is already adjacent to the 35m wide by 32m deep launch shaft for JV contractor Porr/Max Bogl Bauunternehmen to assemble the full back-up train prior to the start of excavation. Driving the single bore line is expected to take about two years.
Geology along the route of Lot 3-4 consists of pebble stones, sand, coarse clay, brash and gravel. The TBM has been designed with cutterhead power of 3200kW, torque of 23,230 kNm, and total thrust of 90,515 kN.
Herrenknecht is also adapting an existing 13.2m diameter TBM down in size to 13m diameter for the project – to drive a 3.74km single bore on Lot 8 (Jenbach) of the project. The machine, brought back from the Stormwater Management and Road Tunnel (SMART) project in Kuala Lumpur, is due on site in the third quarter of the year. A Hochtief-led JV to is commence boring on the lot before the end of this year.
The entire project will see a new twin-track railway open in 2011, and the scheme will be a key link in the planned European mega-project to cut across the Alps to create a major link from Germany to Italy. In addition to the northern access, a southern access route in Italy is required plus the principal challenge of the entire scheme – the Brenner base tunnel, in Austria (T&TI, September 2004, p14-16).
Tunnelling works already or near completed on the Lower Inn Valley link include almost 4.2km of NATM tunnel on Lot 2-1 (Radfeld-Brixlegg), and the excavation using the same method on the 8.38km stretch of Lot 5 (Vomp-Terfens). A short, 671m length of NATM tunnel is due to start excavation in late May on Lot 3-6 (Tiergartentunnel).
More complicated tunnelling using a variety of excavation methods are underway at Lot 4-3 (Stans) and Lot 7 (Fritzens-Baumkirchen), involving jet grouting preparatory works, compressed air working for the main excavation, and some cut and cover.
