Despite the fact that the stretch between the BBT’s northern end and the main station in Innsbruck is comparatively short (only 600 metres), the work required some highly challenging engineering. For example, it was necessary to insert up to 60 anchor bolts, each 120 metres long, into the loose rock of the Viller Berg slopes at the northern portal.
The works were completed within the expected 52-month timeline. The contract was worth 60 million Euro and the construction work was carried out by PORR Bau GmbH of Kematen.
The re-vegetation work meant to restore the construction site to its original state is currently ongoing. This is a very popular recreational area for the residents of Innsbruck; starting in spring of 2025, they will once again have access to the two stretches of the hiking loop that run through the gorge.
Sill Gorge construction lot: works above and below ground
The works here both above and below ground were complicated not only by the presence of the Sill brook, but also because the gorge itself is quite narrow. Also, there are several other pieces of infrastructure in this area, including the A12 Inntal and A13 Brenner highways, the Tirol Panorama Museum, the Untere Sill power plant and the ÖBB rail line in the Bergisel tunnel.
"The Sill Gorge construction lot proved to be particularly challenging, as it included several complex structures", explained Martin Keinprecht, Project Manager for the site. "We bored 170 pilings for the reinforced concrete retaining wall and built three 50-metre steel bridges, a 55-metre span bridge, a reinforced concrete pre-tunnel and the structure of the north portal itself. This goes to show the variety and complexity of the structures built as part of the lot", Keinprecht added.
The construction of the two bridges over the Sill was an important feat of engineering. At the same time, it was necessary to preserve the important recreational area in the Sill Gorge that is so popular with the residents in Innsbruck.
“We’re very pleased to be able to mark the completion of a further construction lot for the Brenner Base Tunnel”, said the two members of BBT SE’s Board of Directors, Martin Gradnitzer and Gilberto Cardola. “The portals are clearly visible from the outside and these two north and south entrances to the BBT in Innsbruck and Fortezza will be the clear and unmistakable face of the Brenner Base Tunnel”.
