The tunnel will run between Innsbruck in Austria and Franzensfeste/Fortezza in northern Italy, creating a direct cross‑border route that spans two countries and two time zones. With an estimated price tag of €8.54 billion (£7.4 billion), the project is one of the most ambitious transport undertakings in Europe’s modern history.

Once complete, the Brenner Base Tunnel (BBT) will integrate with the existing Inn Valley Tunnel, a 12.7km bypass opened in 1994. Together, the two structures will form a 64km continuous underground railway, enabling both passenger and freight trains to travel beneath the Alps with unprecedented speed and efficiency.

Engineers say one of the tunnel’s most unusual features is its exploratory tunnel, a smaller 5‑metre‑wide passage running the full length of the route. Positioned 12 metres below the main tubes, it serves as both a research corridor and a future drainage system.

Current excavation work in the exploratory tunnel is helping teams analyse the rock mass and geological conditions, allowing them to refine construction methods and reduce both costs and delays. Once the BBT becomes operational, the passage will play a crucial role in managing water flow and maintaining long‑term tunnel safety.