Which country built the longest undersea railway tunnel in the world?

With the development of railway and highway traffic, there are more and more underground and submarine tunnels. The earliest land tunnels were two tunnels on the Liverpool-Manchester line developed by Britain in 1830. The earliest underwater tunnel was built from 1825 to 1840 across the Thames in London, England.

In the late 1950s, Japan began to build the Aomori Tunnel, the world's longest undersea tunnel connecting Aomori and Hakodate. It is much longer than the English Channel Tunnel originally planned by Britain and France. It starts from Imabe-machi, Jin Dong, Aomori Prefecture, at the northern end of Honshu, and extends to Shinei-machi, Shangji Prefecture, Hakodate, Hokkaido via Tsutsugaru Strait, with a total length of 53.85 kilometers and an inner diameter of 9.6 meters. The deepest point is below the seabed 100 meter and 240 meters away from the water surface.

Han Qing Tunnel is excavated with a powerful special machine for tunnel excavation, which can dig a hole with a diameter of 4 meters at a time, and the excavation speed is 2 meters per hour. In order to promote this project, * * * dug three tunnels. The first one was a test tunnel to observe the state of soil and the possibility of seawater flooding. The other is a working tunnel, which is used to transport building materials; The last one is the main tunnel, and the inner diameter of the pilot tunnel and the operation tunnel is only half of that of the main tunnel.

After the Han Qing Tunnel is completed and opened to traffic, it will greatly shorten the distance between Honshu and Hokkaido, and take the Shinkansen from Tokyo to Sapporo, the capital of Hokkaido, which will be shortened from the original 16 hours and 50 minutes to 5 hours and 40 minutes. It takes 4 hours and 50 minutes by ferry turbine, and only 13 minutes by shinkansen to cross Tsugaru Strait. At the same time, it is of great strategic significance to strengthen the defense of Hokkaido and invigorate the Japanese economy.