40 Projects International + Special Divisions www.strabag.com Projects International + Special Divisions teams. No. 1 /2017 41

BRENNER BASE TUNNEL Ice under the CONTRACT VALUE: € 303 million The billion-euro project is making progress. CONSTRUCTION PERIOD: November 2014 – December 2022 In October 2014, STRABAG – as part of a bidding consortium – was SHARE IN CONSORTIUM: awarded the contract to build the Eisack river undercrossing. The 39 % first two phases of construction are already complete. CONSTRUCTION PHASES: 3

crossing of the river Eisack will be very difficult as we have a very low rock cover here and the construction of the tunnel must not alter the flow of the river.” The BBT runs quite shallow beneath the surface here. The ground conditions are complex and groundwater is an issue. “For this reason, we are using two special procedures,” In the foreground is the Telepass station built by Mörtl explains. “The first is ground freezing beneath the us along with the access river Eisack using liquid nitrogen to freeze the substrate to the A22 motorway. The silos in the background are so that we can safely bore through it. The second is jet used to produce concrete grouting, which involves injecting a cement/water mixture in part from the aggregate won from the tunnelling under high pressure through a borehole into the substrate works. to solidify the ground.” To determine the geological reaction to these procedures, and to prove their suitability to the client, several tests and trial bores were made over an 18-month planning phase on site.

In the summer of 2016, even before the first two con- struction phases had been finished, work began on the third and – with a value of € 290 million – largest and most important phase: the undercrossing of a highway, Access shafts are being I’m proud that I can play a part built to provide access to the existing railway and the A22 motorway. A total of 6 km in this once-in-a-century project the main tubes. These . Since the start of construction on the Brenner of tunnel will be excavated using various conventional will remain as emergency exits following tunnel Base Tunnel (BBT) in August 2007, quite a lot has methods such as drilling and blasting or hydraulic connecting Europe. completion. In the picture: happened on the northern end of . Now breakers. The two main tubes cover a length of 4 km. emergency exit 4 with Leopold Mörtl tunnel ventilation. the focus is on the southern end. In October 2014, the The remaining 2 km involve access shafts, connecting € 303 million contract for the Eisack river undercrossing tunnels with the existing railway and cross passages to was awarded to a bidding consortium consisting of the the two main tunnels. two Italian STRABAG subsidiaries Sede Secondaria and STRABAG S.p.A. The other partner companies are Salini Impregilo S.p.A., Collini Lavori and Consorzio Integra. Leopold Mörtl, commercial project manager When it is completed at the end of 2022, the BBT will be linked with the existing and the Italian station of . But until the actual tunnelling for the tubes can begin, a lot of preparatory Tunnel wastewater treatment facility Luftaufnahme aus work remains to be done. Bauphase 1 – Er- schließung des Baufelds

THE LARGEST CHALLENGE IS STILL TO COME

“The project is divided into three construction phases,” says the commercial project manager Leopold Mörtl. The first two – the site development, the construction of Jet grouting involves injecting a cement/water mixture a new railway undercrossing and the motorway access under high pressure through a borehole (in the picture: to the A22 including loading station as well as the detailed the borehole probe in use) into the substrate to solidify the ground. A part of the shaft used to later carry out the construction design – were realised between October 2014 ground freezing under the Eisack has already been bored. and December 2016. The site development required the rerouting of state highway SS12 as well as the construction of two bridges over the Eisack and Weißenbach rivers. “We now face the greatest technical challenge in the third CONTACT: construction phase,” says Mörtl. “Above all, the under- Leopold Mörtl, Subdivision Italy (IZ)