The Europe-wide tender was carried out according to the best bidder principle. Swietelsky was already responsible for the preliminary lot “Wolf II” (construction period: 2013–2017) of the Brenner Base Tunnel.
The new construction lot H52 “Hochstegen” is a section of the former construction lot H51 “Pfons–Brenner”. This previous project section was divided into several construction lots for the purpose of ensuring that the work can be continued as quickly and efficiently as possible.
Hochstegen – a Challenging Geological Zone
The area of the new construction lot Hochstegen is located in a geological fault zone with extremely complex geology. Over a length of approximately 500 m, water-bearing, carbonate rock layers predominate. This makes tunnelling in this zone particularly challenging.
A total of about 2.6 km of main tunnel in the direction of Brenner, 0.6 km of connecting tunnels, five cross-passages and 1.2 km of exploratory tunnel in the southern direction have to be excavated. In addition, there is a 2.5 km long remaining excavation of the crossover at the Wolf South junction. The centrepiece of the project, however, is the excavation of the exploratory tunnel to the south through the so-called “Hochstegenzone”. The excavation in this area will be protected by advance sealing and stabilisation injections.
Overall Progress of the Brenner Base Tunnel Project
At the beginning of 2022, two new construction sections will start on Austrian project territory with the two lots H41 “Sillschlucht–Pfons” (contract awarded on 17 November 2021) and H52 “Hochstegen”.
Of a total of 230 tunnel kilometres of the Brenner Base Tunnel, 148 km have already been excavated, of which 53 km are railway tunnels, 54 km are exploratory tunnels and 41 km are other structures.