BRENNER BASE TUNNEL
The strategic rail link in the Scan–Med Corridor
Situated at the heart of the Alps and characterised by the lowest altitude among the major mountain passes (1,371 m above sea level), the Brenner Pass has historically been a key route for European transport links. Today it handles around a quarter of all transalpine freight traffic, confirming its status as one of the main transport corridors between northern and southern Europe. The project forms part of the European TEN-T ‘Scandinavia–Mediterranean’ Corridor, a strategic route linking Helsinki to Valletta over a distance of more than 9,400 km, crossing Central Europe and Italy. Within this context, the Brenner system constitutes one of the most significant infrastructure hubs along the entire corridor.
The railway project
The project delivers a direct link between Innsbruck, in Austria, and Fortezza, in Italy, via the Brenner Base Tunnel (BBT), which stands as one of the longest railway tunnels in the world. The infrastructure stretches for 55 km between Fortezza and Innsbruck, extending to 64 km when including the Innsbruck railway bypass. The new line, designed for speeds of between 200 and 250 km/h, features a modern alignment featuring a significant reduction in gradients and distances compared with the legacy line, bringing major benefits in terms of capacity, operational efficiency, and environmental sustainability.
The Brenner Base Tunnel
The Brenner Base Tunnel is one of the most significant engineering projects in Europe and is intended to strengthen links between Italy and Austria along the north-south rail axis. Forming part of the Scandinavia–Mediterranean Corridor, the project will contribute significantly to the expansion of rail freight transport and the reduction of transalpine road traffic. The infrastructure is designed as a high-tech, interoperable railway system, equipped with advanced electric traction, telecommunications, signalling, control and safety systems. The system comprises two single-track main tunnels, connected by cross-passages every 333 metres, transverse access shafts, and an exploratory/service tunnel linked to the main bores via vertical shafts approximately every 1,000 metres, supporting both the construction phases and subsequent maintenance and emergency response activities.
The role of FS Engineering
FS Engineering, as leader of the consortium set up with Systra, ILF Consulting Engineers Austria and EUT Engineering Srl, has been involved since May 2024 in designing strategic project components, such as the technical systems, trackwork and other required works for commissioning the BBT tunnel. The cross-border nature of the project requires a high level of technical integration between the Italian and Austrian railway networks and full compliance with European interoperability standards. Besides the base tunnel proper, the project also comprises the cross-border sections, the northern access line between Munich and Innsbruck, and the southern access line between Fortezza and Verona. The latter runs entirely in Italy, along the Isarco and Adige valleys, for approximately 180 km, and involves the quadrupling of the legacy line. The northernmost section is Lot 1, Fortezza–Ponte Gardena, which runs predominantly in tunnels, over a distance of 22.5 km.
The Isarco River underpass
FS Engineering was commissioned by BBT – Brenner Base Tunnel to carry out project management and site supervision for the underpass beneath the River Isarco, in the southern section of the tunnel. This is the most significant lot of the entire project, involving the construction of approximately 4.5 km of main line tunnels and 1.6 km of connecting tunnels to Fortezza station. The particular complexity of the site, due to interference with the River Isarco, the Brenner Motorway, the SS 12 main road and the Verona–Brenner railway line, required the adoption of high-tech engineering solutions, including artificial ground freezing to enable safe excavation work beneath the riverbed. The works have been successfully completed.
Benefits and sustainability
The technical and construction features of the new railway link, in particular the reduced gradients and the underground section of the line between Verona and Innsbruck, will significantly improve the overall performance of the rail system, reducing energy consumption by up to 40 per cent and CO₂ emissions. The infrastructure will also enable a more efficient separation of freight and passenger flows and between long-distance and local services, with significant benefits in terms of capacity, punctuality, and service quality, as well as a significant reduction in noise pollution in the areas concerned.
The project is currently scheduled for completion in 2032, representing a key step towards a more integrated, efficient, and sustainable European transport network. The design of the technical systems is at an advanced stage of development and is expected to be completed by 2026.
