What is the longest tunnel in the world?

The longest tunnel in the world is the Gotthard Base Tunnel, which stands as the pinnacle of tunnel engineering due to its impressive length of approximately 57 kilometers (35 miles). It was officially opened in June 2016 and is located in Switzerland, primarily serving as a railway tunnel that significantly reduces travel time across the Swiss Alps. The design and construction of the Gotthard Base Tunnel involved sophisticated engineering techniques, making it a marvel of modern construction, designed to improve the efficiency of rail transport across mountainous terrain.

The Channel Tunnel is a key railway connection between the UK and France, but while it is a remarkable engineering feat, it is not as long as the Gotthard Base Tunnel. The Delaware Aqueduct, primarily a water supply tunnel in the United States, is extensive but is technically not classified with respect to rail or road transport. The Seikan Tunnel, while the longest undersea tunnel, is also shorter than the Gotthard Base Tunnel. Understanding these comparisons illustrates why the Gotthard Base Tunnel holds the record for the longest tunnel in the world.