The Brenner Base Tunnel: shifting Alpine traffic from road to rail

18 September 2024, the Brenner Base Tunnel, located between Austria and Italy, celebrated in the Pfons-Brenner site (Austria) the start of the excavation of the two Tunnel Boring Machines (TBMs), named Wilma and Olga. These are the last two TBMs entering into service, for achieving the BBT tunnelling. Representatives of the European Commission and CINEA attended the ceremony to celebrate this important milestone made possible thanks to EU funding.

The Brenner Pass is one of Europe’s busiest mountain crossings used for freight transport. Each year, more than 2.5 million trucks, 14 million vehicles, and 50 million tonnes of goods cross the Alpine pass. The new Brenner Base railway tunnel, co-funded with €2.3 billion for four Actions from the CEF Transport programme, aims to ease congestion on the Munich-Verona route, which is part of the Scandinavian-Mediterranean Corridor that stretches from Helsinki to La Valletta.

The current railway follows a route established in 1860, winding up the 1,371-metre-high mountain road with steep slopes of up to 26%. This design limits train speed and maximum load capacity, requiring at least two locomotives on the Italian side and three on the Austrian side. As a result, the existing railway is not competitive for cross-border freight or passenger transport.

The new Brenner Base Tunnel addresses these issues on the most critical part of the stretch by providing a nearly flat, straight route. At 64 km, it will be the world’s longest underground railway tunnel. With slopes of only 4 to 7 %, it runs 580 meters below the Brenner Pass. The tunnel will reduce the Fortezza – Innsbruck line by 20 km. In the planning phase, freight trains were estimated to reach speeds of 160 km/h, and passenger trains up to 250 km/h, cutting travel time from 80 to just 25 minutes.

The Brenner Base Tunnel will consist of two single-track tunnels, each 8.1 m wide and spaced 40 to 70 metres apart. Traffic through these tunnels will be one-way, and they will be connected with bypasses every 333 metres for safety. A smaller exploratory tunnel will run between and below the two main tunnels, used for drainage, maintenance, and technical installations. The excavations on the pilot tunnel have provided important knowledge on the rock mass, which reduced construction risk, costs, and times to a minimum. To the south, the new line will connect to Fortezza via two single-track tunnels. To the north, it will link to the Innsbruck bypass and the lower Inn valley railway, as well as to Innsbruck railway station.

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