BERN - Rail journeys across the Swiss Alps will take longer for the next few months after a major derailment has left the record-breaking 35-mile (57-kilometer) Gotthard Base Tunnel partially out of action. The world’s longest tunnel was closed last week when a freight train jumped the tracks, derailing 16 carriages and damaging about five miles of rail lines, Swiss national rail operator SBB said in a statement. SBB said the tunnel will reopen partially on August 23, with one of the two lines through the mountains unaffected by the incident. But the reduced capacity will mean re-routing passenger trains via a scenic railway that takes up to two hours longer until early 2024. “Until further notice, passenger trains will be diverted via the panorama route,” the SBB statement said. “The journey time is extended by 60 minutes in national traffic and between 60 and 120 minutes in international traffic.” The company said it was examining whether passengers could be safely transported with only one track in operation but for the time being it would be closed to non-freight traffic until further notice. Opened in 2016 after 17 years of construction, the Gotthard Base Tunnel has become a vital railway link between northern and southern Europe, as well as a destination for rail enthusiasts wanting to traverse the world’s longest and – at almost 1.5 miles below the surface - deepest tunnel. The structure runs between Erstfeld on the northern side and Bodio in the south, connecting rail traffic between the Swiss city of Zurich and Milan in Italy.