Webuild: TBM “Kathrin” starts excavation of Gardena Tunnel on Fortezza–Ponte Gardena Lot for Brenner south access

TBM “Kathrin” begins most challenging phase of project beneath the Alps after completing Funes access adit

This key infrastructure along the Brenner axis will strengthen the Southern Access to the Base Tunnel and improve rail flows between Italy and Central Europe, increasing capacity, speed and sustainability of the Alpine link

MILAN, May 13, 2026 – Excavation of the Gardena Tunnel, part of the new Brenner rail axis, has officially begun. Tunnel-boring machine (TBM) Kathrin has started boring the Fortezza–Ponte Gardena lot. Located in the region of Trento Alto Adige, the project, carried out by the Webuild Group on behalf of RFI (FS Italiane Group), will reshape freight and passenger transport flows across the Alps.

The launch of the TBM follows the completion of the so-called Funes “window”: a 650-metre exploratory tunnel that opened access to the mountain massif. From here, Kathrin – a 144-metre-long giant with a cutterhead nearly 10 metres in diameter – will proceed excavating the twin tubes that will comprise the Gardena Tunnel, as well as the interconnection tunnels with the future Ponte Gardena station. Overall, the plan includes the excavation of more than 16 kilometres of tunnels and the installation of approximately 9,000 precast concrete segments.

The Fortezza–Ponte Gardena lot is being built by a consortium led by Webuild, with Implenia and the participation of SELI Overseas, the Group’s tunnelling specialist subsidiary, as partners. The new rail line that will eventually pass through it represents the first segment of the quadrupling of the southern access of the Munich–Verona route. The project is almost entirely underground, with a total of 52 kilometres of tunnels designed to reduce gradients compared to the existing line, significantly increasing speed and freight transport capacity.

Designed to tackle complex geology, Kathrin is a “dual mode” TBM, capable of alternating between hard rock excavation and more unstable sections. This flexibility has already been successfully tested during the undercrossing of the Brenner highway, carried out without interrupting surface traffic. The machine also stands out for its sustainable footprint: thanks to highly efficiency motors and cooling water recovery systems, Kathrin reduces energy consumption per cubic metre excavated by 20–25 percent compared with traditional models.

As Kathrin advances, work proceeds on other fronts. At the Forch cavern, preparations are underway to excavate the Scaleres Tunnel (15 kilometres), while at the Chiusa access adit, 1,400 of the planned 1,800 metres have already been completed. Activities involve geologists and operations teams working simultaneously at multiple sites, including tunnels and a 250-metre viaduct over the Isarco River and upgrades to the Ponte Gardena station.

Webuild’s commitment to this project is part of the broader Brenner Base Tunnel system which, at 64 kilometres, will become the world’s longest underground railway tunnel. Webuild is a key player in this engineering challenge on both sides of the Italy-Austria border, with the construction of a total of around 50 kilometres divided into four lots. For the Brenner Base Tunnel, on behalf of BBT SE, the Group is involved in the Mules 2-3 on the Italian side, where TBM excavation was completed in May 2025, and in the Sill Gorge–Pfons lot in Austria. It has already completed the Tulfes–Pfons lot, also in Austria, and the Isarco underpass Lot in Italy. Webuild is also involved in the construction of the Trento railway bypass. Once completed, the entire Brenner system will revolutionise transalpine transport. Its dual objective is to reduce travel times and shift freight traffic from road to rail, strengthening one of the most vital corridors connecting the Mediterranean and Northern Europe.