It is only when a visitor is allowed a peep in front of the boring machine digging the Amsteg-Sedrun section of what will become the world's longest rail tunnel that the project's audacity becomes clear.

In other parts of the construction site for the Gotthard Base Tunnel, which will consist of two 57km tubes under the Gotthard Pass in the Swiss Alps, some concrete and other coverings have already been applied to the tunnel walls, masking the harsh, uneven rock through which the tunnel is being driven. But, when the machine's cutting face is drawn back a little for maintenance, visitors can squeeze past into a granite-lined cylindrical cavern nearly 10 metres in diameter. Boulders from the cavern's still-unstable, newly excavated sides litter the floor. The front wall is lined with neat circles from the machine's drilling bits, which bite into the rock with a pressure of 28 tonnes each.