The NRLA (The Swiss New Rail Link through the Alps) is a new rail link that consists of three base tunnels running through the Alps, in Switzerland. Two of the tunnels have been completed, but one is undergoing a major expansion.

The rail link features the Gotthard Base Tunnel, which is the world's longest railway tunnel, the Ceneri Base Tunnel, and the Lötschberg Base Tunnel. Although the NRLA was completed in 2020, the Lötschberg Base Tunnel is currently being expanded, with completion planned by 2035. The project, which cost around 12.2billion Swiss francs (£11.3billion), aims to reduce road traffic as well as environmental impact.

The Swiss New Rail Link connects eight cities across two countries: Zurich, Basel, Lugano, Bellinzona, Lucerne and Bern, in Switzerland, with Milan and Genoa in Italy.

Switzerland has dug more than 1,400 tunnels into its landscape over the years, stretching 2,000 kilometres (1,242 miles) underground.

The Federal Department of the Environment, Transport, Energy and Communications said: "The NRLA is the largest construction project in the history of the Swiss railways.

"The Gotthard Base Tunnel went into operation in 2016 and, at 57 kilometres, is the longest railway tunnel in the world. It took 17 years to build.

"At 15,4 kilometres long, the Ceneri Base Tunnel is the third-largest NRLA construction project. The portals are located in Camorino (Bellinzona) in the north and in Vezia near Lugano in the south.

"The Federal Council wants to expand the Lötschberg Base Tunnel to two tracks throughout by around 2034. This will create additional capacity and increase operational stability, allowing a continuous half-hourly service for passenger transport."

Another significant project, currently under construction, is the Brenner Base Tunnel (BBT), which will connect Austria and Italy.