Page 9 - TunnelTalk Annual Review 2014

Brenner Baseline pushes ahead
The next major phase of tunnelling on the Brenner Base Tunnel has begun in the Alps between Austria and Italy with the Strabag and Salini Impregilo JV making an official start of excavation on its 55-month, €377.3 million contract for the mega project’s Tulfes-Pfons Lot. Located at the Austrian end of the €8.6 billion scheme (in 2012 prices), the Tulfes- Pfons Lot calls for a total of about 38km of drill+blast and TBM excavation.
At the same time, the Strabag Salini-Impregilo, Consorzio Cooperative Costruzioni CCC, Collini Lavori JV was awarded €300 million construction of the Eisack River undercrossing of the alignment located at the Italian end of the project near the town of Franzensfeste (Fortezza). Contract scope comprises construction of the two Base Tunnel main tubes for a total of 4.3km and two connecting tunnels to the existing Brenner Railway. As well as the River Eisack undercrossing, the route passes under the Brenner Motorway, the state highway and the Brenner Railway with a very low rock overburden.
While the scale and values of the two lots are substantial, the packages are to be followed by three larger contracts for the project. The client, Brenner Basis Tunnel (BBT-SE), a JV of the Austrian and Italian rail companies, ÖBB and TFB respectively, plans to start procurement for these final three largest lots in 2016, said Simon Lochmann, the Head of Communications for BBT-SE.
The Tulfes-Pfons Lot awarded to Strabag-Salini Impreglio has four areas of tunnel works:
• A new 15km section of exploratory
tunnel;
• A 9.1km long safety/rescue tunnel;
• Two large connecting tunnels totalling
• A short extension of the twin main base tunnels by about 5km at the Ahrental adit area.
Drill+blast excavation started in
September, and a TBM drive is scheduled to launch in mid-2015.
Baseline design
In the overall project layout, the Brenner Base Tunnel scheme comprises an exploratory/drainage/service tunnel running between, and slightly below, the two main running tunnels for the full length of the project. The 8.1m i.d. main running tunnels are 70m apart, linked by cross passages every 333m, and have multifunctional emergency stations, with access to the surface, at 20km intervals (Fig 1).
The geology on the alignment comprises quartz phyllite, slates, gneiss and granites with several identified faults and anticipated hydrogeological challenges. “So far, a total of about 12km of the exploratory tunnel has been excavated along the main axis of the project in
Fig 1. Latest schematic of the 55km long Brenner Base Tunnel from the Innsbruck North Portal in Austria (left) to the Fortezza South Portal in Italy (right)
Patrick Reynolds, TunnelTalk
addition to a few short lengths of the main tunnels at adit junctions,” said Lochmann.
The portions of exploratory tunnel excavated to date were undertaken in two sections, one at each end. At the north Austrian end, the Strabag/Porr JV completed drill+blast excavation of the section to the first adit junction at Ahrental. At the southern Italian end, the longest exploratory bore advanced from Aicha (Aica) using a 6.3m diameter double shield TBM. The 10.5km bore, which started off-line and reached the Mauls (Mules) adit between the main running tunnels, was excavated by SELI, as part of the JV with Pizzarotti, Bilfinger Berger, Alpine Meyreder, Beton– und Monierbau, Jaeger, Collini and Societa ItalianaperCondotted’Acqua.
To extend the exploratory tunnel in the Tulfes-Pfons Lot, the Strabag-Salini
some 9km in length; and
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