The Gotthard Base Tunnel, opened in 2016, is a railway tunnel that lays in the heart of the Swiss Alps. With a total of 151.84 km (94.3 mi) of tunnels, passages, and shafts, and a route length of 57 km, it is the longest and deepest rail tunnel in the world which surpasses the Seikan Tunnel in Japan, which previously held the record.
The main purpose of the Gotthard Base Tunnel is, of course, to increase total transport capacity, especially freight, across the Alps. It was built more particularly to reduce environmental damage caused by numbers of heavy lorries by shifting freight volumes from road to rail. Additionally, it cuts the journey time for passenger trains by approximately an hour, depending on the route.
The project is a big step forward; thus, it took around 20 years of constant preparation and construction. The cost of it was $10.3 billion. Check it out!