Complex Isarco River excavations in Italy 27 Jul 2016

Following two years of preparatory site works, excavation is under way of the complex Isarco River undercrossing at the southern end of the Brenner Baseline Tunnel.

Complex excavations of the 5.8km Isarco River Crossing

The 5.8km-long section of the 55km tunnel that will eventually link Fortezza in Italy with Innsbruck in Austria, is being excavated by the Isarco Consortium led by Salini Impregilo, with Strabag, Collini Lavori and Consorzio Integra as partners. The €301 contract was awarded in 2014 and is scheduled for completion in 2022.

At an inaugural event attended by local and national officials, along with representatives of the companies involved in the project, construction work began on the southern section of the railway tunnel at Fortezza. This follows completion of preparatory works that included the rerouting of the SS12 Brenner State Road, construction of a new road, as well as construction of a loading and unloading area next to the southern lane of the highway.

The construction of the southern section of the Brenner Baseline Tunnel is particularly significant for its technical complexity. Two main tubes and two junction tunnels to the existing railway infrastructure will be driven using conventional means under the Isarco River.

At this challenging location liquid nitrogen will be used to freeze the earth between the 60m-long tunnels and the riverbed. The remainder of the 5.8km main tunnels is expected to involve considerable use of jet grouting to stabilise the predominantly soft ground geology.

Salini Impregilo, along with its JV partner Strabag, also holds the mixed drill+blast/TBM-bored Tufles-Pfons Lot at the northern end of the Brenner Tunnel. As part of these works, which stretch to a total of 38km of excavations, a 7.93m diameter Herreknecht TBM was launched in September 2015.