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Moving Mountains

The Gotthard Base Tunnel is actually two main parallel tunnels measuring a record-breaking 57km each, served by a maze of access tunnels, shafts and passages. In total there will be 153.5 km of tunnel through the Swiss Alps.

The project has been conceived to solve the problem of heavy European road traffic on this major route through the Alps, while simultaneously developing Europe’s high-speed rail network. The existing tunnel, much higher up, can only handle three-truck freight trains of up to 2,000 tons. The new tunnel will take 4,000 ton heavy freight trains – carrying entire trucks on board - effortlessly through the heart of the mountains. Passenger trains will be able to travel at speeds of up to 250kmph, resulting in a train journey time between Zurich and Milan of just two hours and 40 minutes – a third less than at present.

But digging a tunnel underneath 3,000m mountains is going to take all the skill of some of the world’s leading engineers. Much of the geology that lies beneath the mountains was unknown when the project began. Problems that would slow the project down and give rise to complex engineering challenges have been a feature of building the tunnel.

The planned completion date is 2015 but that may well slip. In fact, in July 2005, a tunnel boring machine (TBM), known as Gobi II, got stuck when it unexpectedly encountered a section of unstable, soft rock. The tunnel promptly collapsed in front of the TBM’s cutting head – and there is no such thing as reverse with a tunnel boring machine. Experts on the project found themselves with the unexpected task of trying to calculate the extent of the section of less stable rock, as well as having to rescue the TBM by digging it out of the place where it had got stuck – a process that would take several months.