TBM milestone as 400,000 precast segments drive Brenner tunnel forward

Mechanised excavation has now been completed on the Italian side of the Brenner Base Tunnel (BBT), with TBM Flavia finishing her 14 km drive through the Alps as part of the Mules 2–3 lot. The milestone marks another step towards delivery of what will become the world’s longest railway tunnel — and one of the most ambitious precast concrete applications in European infrastructure.

According to project sources, over 400,000 precast segments are being produced for use in the tunnel lining — around 26,000 complete rings so far. These elements form the permanent structural lining of the tunnel, installed directly behind the cutterhead of each tunnel boring machine (TBM). Each segment weighs up to 17 tonnes, and combined they represent an estimated 1.7 million tonnes of concrete, or approximately 700,000 cubic metres. These figures are based on information from project partners including Simem America and BBT SE.

At 64 km, the Brenner Base Tunnel will link Fortezza in Italy to Innsbruck in Austria, bypassing the existing Brenner Pass route and significantly reducing journey times for both passengers and freight. Trains will run at speeds of up to 250 km/h, cutting travel time from 80 minutes to just 25 between the two cities.

The tunnel is a key component of the Scandinavian–Mediterranean Corridor of the EU’s TEN-T (Trans-European Transport Network), and a central section of the Munich–Verona axis. Its purpose is to encourage modal shift from road to rail across the Alps, cutting greenhouse gas emissions and improving logistics performance across Europe.

Lot Mules 2–3, delivered by a consortium led by Webuild on behalf of BBT SE, is the largest section of the tunnel on the Italian side. It includes over 65 km of underground works, with more than 40 km excavated using TBMs. TBM Virginia completed the eastbound tunnel in March 2023, and Flavia has now concluded the westbound drive. The lot is reported to be 98% complete.

In addition to Mules 2–3, Webuild has worked on other sections of the wider tunnel and rail corridor. These include the Isarco River underpass, which forms the southernmost point of the main tunnel, and the Sill Gorge–Pfons lot in Austria. Webuild also previously completed the Tulfes–Pfons section and is currently upgrading other connected lines, including the Fortezza–Ponte Gardena route and the Trento Bypass.

Once finished — now expected by 2032 — the Brenner Base Tunnel will be not only the longest but also one of the most environmentally transformative rail tunnels in Europe, enabling more efficient, lower-carbon transit across the Alps and beyond.