The $3.5bn tunnel runs between Frutigen in Berne and Raron in Valais and will allow for passenger trains travelling at up to 250kph (156 mph) to speed through, making access to many ski resorts far quicker, cutting transport time to Valais from Berne by a half.

It is hoped the tunnel, the longest land tunnel yet, will also lead to a reduction of road traffic on Swiss roads.