Isarco underpass construction site: tunnel work completed

In the southernmost lot of the Brenner Base Tunnel, the construction work for the future railway tunnels has been completed and work is now being carried out on the area outside the construction site.

On 8 August, construction work on the future line tunnels in the 'H71 Isarco Underpass' lot at Fortezza was completed. In eight years of work, more than 6 km of tunnels and their interior lining were constructed. In the final phase of the work, the construction site will be “demobilised” and the areas will be greened, in accordance with the seasonality of the tree species.


In 2015, construction work began on construction lot H71 for the Isarco River Underpass near Fortezza. In the Upper Isarco Valley area, 4.5 km of main railway tunnels and 1.5 km of interconnecting tunnels with the existing railway line were built. Although the stretch of the route was relatively short, the works were highly complex both in terms of the construction techniques used and the passage under the river. Some tunnel sections run not only under the Isarco River, but also under the A22 motorway and the SS12 state road. The aim is to connect the Brenner Base Tunnel to the existing railway line as well as to the new high-speed, high-capacity line under construction between Fortezza and Ponte Gardena.


In this construction lot, in order to be able to excavate under the river using the technique of soil consolidation by freezing, two shafts were built on each side of the river, each about 25 metres deep. Ground freezing is an environmentally friendly technique and it was chosen so that the Isarco could continue to flow in its original riverbed, preserving the flora and fauna in the area. Today, the four shafts are almost completely filled in with excavated material.


Alessandro Marottoli, Director of Proceedings for BBT SE for the Isarco River Underpass construction lot, expressed his satisfaction by remarking: “The completion of the Isarco Underpass tunnels is an important milestone for the Brenner Base Tunnel project. In the final phase of construction, where we are now, it is crucial to restore the areas affected by the works to their original state.