Seikan Tunnel Japan

The 53.85km Seikan tunnel in Japan is the longest and deepest rail tunnel in the world. It passes through Tsugaru Strait connecting the Hokkaido and Honshu islands.It was built 100m below the seabed and includes a 23.3km submarine portion. It was officially opened in March 1988 and is used for the operation of express trains.The tunnel was sponsored by Japan Railway Construction, Transport and Technology Agency and is operated by JR Hokkaido. The internal height and width of the tunnel is 7.85m and 9.7m respectively.The tunnel was built using 168,000t of steel, 1.74 million cubic metres of concrete and 2,860t of explosives. Seikan Construction Bureau was the main construction contractor. Two stations, Tappi Kaitei and Yoshioka Kaitei, are located inside the tunnel.