Seikan Tunnel

The Seikan Tunnel is a 53.85-kilometer railway tunnel beneath Japan’s Tsugaru Strait, linking Honshu and Hokkaido. Its undersea section and deep approach tunnels make it one of the world’s longest railway tunnels.

Tsugaru Strait: A strait in northern Japan separating Honshu from Hokkaido and connecting the Sea of Japan with the Pacific Ocean. The tunnel passes beneath this strait, whose depth and seabed shaped its route.
Toyamaru ferry disaster: A 1954 maritime disaster in which the ferry Toya Maru and several other vessels sank in a typhoon in the Tsugaru Strait. The loss of life intensified calls for a fixed rail link between Honshu and Hokkaido.
Hokkaido Shinkansen: A Shinkansen line connecting Aomori in northern Honshu with Hakodate and other destinations in southern Hokkaido. The line began using the tunnel in 2016, bringing high-speed passenger trains to Hokkaido.
Channel Tunnel: A railway tunnel beneath the English Channel linking Folkestone in England with Coquelles near Calais in France. Both tunnels cross major straits, but the Channel Tunnel connects two countries and carries road vehicles in trains.
Undersea tunnel: A tunnel constructed beneath a body of water, usually through the underlying seabed or rock. The Seikan Tunnel is a railway example, with much of its route beneath the strait.
Japanese National Railways: Japan’s state-owned railway company, which operated the national rail network until its privatization in 1987. The company investigated and built the tunnel before its 1988 opening.
Freight train: A train that transports goods rather than passengers. Freight trains share the tunnel with passenger services on its dual-gauge track.
Gotthard Base Tunnel: A 57.1-kilometer railway tunnel through the Swiss Alps, opened in 2016. It is longer overall than the Seikan Tunnel, though it runs beneath mountains rather than a strait.
Tunnel boring machine: A machine that excavates tunnels through soil or rock while supporting the surrounding ground. Mechanical excavation helped drive the tunnel’s long underground sections through difficult geology.
Seikan Tunnel construction: The decades-long engineering project that excavated and completed the Seikan Tunnel beneath the Tsugaru Strait. Its exploratory works and main excavation explain how the tunnel was realized.

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