The world's longest and deepest rail tunnel, running under the Swiss Alps, will be inaugurated Wednesday.
The 57-kilometer-long Gotthard Base Tunnel (GBT) will connect northern and southern Europe and shorten travel time for many rail routes. It overtakes Japan's Seikan tunnel, which measures 53.9 kilometers, as the longest rail tunnel in the world.
German Chancellor Angela Merkel, French President Francois Hollande and Italian Prime Minister Matteo Renzi will join Swiss authorities for a ceremonial first run through the tunnel on Wednesday. Full service will begin in December.
The tunnel runs between Erstfeld in central Switzerland's Uri canton and Bodio in the southern Ticino region. Railway trains traveling at speeds up to 200 kilometers per hour will cut the journey between Zurich and Milan by roughly an hour, to two hours and 40 minutes.
The Swiss federal railway service estimates passenger traffic along the route will increase from 9,000 people a day to 15,000 by 2020.
The tunnel was built in 17 years by 2,400 workers, at a cost of over $12 billion. The massive rig used to bore through the mountains, measured at 410 meters long, removed 28 million tons of rock.
The GBT is part of a network of upgraded alpine links that Swiss voters approved in a referendum in 1992. The environment-friendly project includes three big railway tunnels: the first one opened in 2007, the highly anticipated Gotthard Tunnel and a third tunnel due to open by 2020.
Basel-born Swiss engineer Carl Eduard Gruner proposed a new rail tunnel below the Gotthard Pass in 1947, in a technical paper called "Journey through the Gotthard Base Tunnel in the year 2000."