The world’s longest tunnel

Saint Gotthard Base Tunnel, on the new railway connection under the Alps, is a total of 57 kilometres long, making it the longest railway tunnel under construction in the world.

Altogether, the system's tunnels add up to 153.5 kilometres in length, including service sections and connections between the tunnel's two tubes. The tunnel runs through the centre of Switzerland at an average of 550 metres above sea level, and it is scheduled to be opened to traffic in 2017.


For the structure's construction, Saint Gotthard Base Tunnel was divided into five separate sections. Two of these sections, the Faido section (14 kilometres) and the Bodio section (15 kilometres) are being built by a consortium led by FCC's Austrian subsidiary ALPINE, which is in charge of building the two one-way tunnels, systems, rail infrastructure and eleven kilometres of railroad on the surface to link the tunnel up to the existing rail system.

Geologically, Saint Gotthard Base Tunnel is primarily compact granite and gneiss, with large fault zones between the two facies. At its deepest point, it carries 2,500 metres of earth on its back.

Roughly speaking, the project calls for twin one-way tubes to be built a distance of 40 metres apart as measured between central axes, with cross-connections every 300 to 325 metres. Two multi-purpose/emergency areas (MFSs, or multi-function stations) are designed into the tunnel as well, for housing the complete set of railway equipment and evacuating passengers and train staff. These areas have been conceived to enable trains to be diverted from one tube to the other during maintenance work or potentially in the event of an emergency.

ALPINE's two sections of the tunnel were bored using TBMs. The TBM for the Bodio section measured 8.80 metres in diameter, and the TBM for the Faido section was 9.50 metres in diameter.

The tunnel has been designed to create a fast connection between Basel and Milan, and it will link Switzerland up to the high-speed European rail system. When the tunnel is operational, it will double the goods-shipping capacity along the north/south Swiss corridor to 40 million tons and cut down the time it takes to travel from Zurich to Milan to two hours and 40 minutes, around an hour less than the current trip. Future passenger trains will be able to cross the Alps at a maximum speed of 250 kilometres per hour.