The Gotthard Base Tunnel is the world’s longest railway tunnel and carries high-speed trains through the Swiss Alps.
The twin-bore tunnel is 57.1 kilometres long and opened to regular rail traffic in December 2016. It forms the central part of the New Railway Link through the Alps, a major Swiss project designed to create a flatter, faster route for passenger and freight trains between northern and southern Europe.
Unlike older alpine routes that climb steep gradients, the Gotthard Base Tunnel passes deep beneath the mountain massif at relatively low elevation. Passenger trains can travel through it at speeds of up to 250 km/h, although actual journey times and speeds depend on the service and the wider network.
The tunnel is sometimes confused with the Channel Tunnel, which is longer when measured by its total rail route beneath the sea but is not the world’s longest railway tunnel overall. The earlier Lötschberg Base Tunnel is another Swiss alpine tunnel, but it is shorter.