China is building a 9,400ft long tunnel UNDER THE SEA as part of a £2 billion 'super' subway line
- Workers need to drill through a series of huge caves in the seabed under Dalian
- The sub-surface shaft lies as deep as 74.8ft under the bottom of the Yellow Sea
- A mammoth tunnel boring machine has been designed and built for the project
- The tunnel is part of the Dalian Metro Line 5 which is expected to open in 2023
Chinese engineers have started to drill a 9,400-foot-long tunnel in the seabed as part of a 'super' subway line that will cost £2 billion to build.
To dig the sub-surface shaft in north-eastern China, workers need to break through rock as deep as 74.8 feet under the bottom of the Yellow Sea.
The land forms of the seabed are extremely complicated and the construction machines will need to cut through a series of huge caves in the seabed, according to a lead engineer.
The largest cave found so far is 95 feet tall, the equivalent of a 10-storey building.
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Workers in Dalian, China, started to drill the tunnel today with the help of a boring machine
The underwater passage spans across the Suoyu Bay of Dalian, a city with six million people
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The deepest part of the tunnel is about 164 feet from the surface of the sea, meaning the drilling machine will need to bear enormous water pressure, adding to the difficulties of the project, according to Wang Jian, the chief engineer of the project.
The construction, which officially began today, is so challenging that it has been billed as a 'super undersea project' by media.
The tunnel is expected to complete in June 2021.
The tunnel boring machine, the Haihong Hao, is developed and built just for the 'super project'
The Haihong Hao is said to be the most advanced tunnel boring machine developed by China
The underwater passage spans across the Suoyu Bay of Dalian, a cosmopolitan city with about six million residents in the Liaoning Province.
It connects two stations of the Dalian Metro Line 5, which has 18 stations in total and is expected to complete in 2023, according to a verified social media post released by the press office of the Dalian government.
In order to perform the previously impossible, Chinese engineers developed a mammoth tunnel boring machine to drill through the seabed.
The impressive equipment, named Haihong Hao, is 518 feet long with a diameter of 40 feet. It weighs a whopping 2,840 tonnes and is said to be the most advanced tunnel boring machine China has developed.
In a ceremony this morning, the Haihong Hao started to excavate the tunnel from the Suoyu Nan Station - a new station built for the Metro Line 5 - towards the other side of the bay.
The Suoyu Bay tunnel is part of the Dalian Metro Line 5 which is expected to complete in 2023. Commuters are seen riding in a subway train in Dalian in 2017 in the file photo above
The Dalian Metro Line 5 is not the first subway line in China to have an undersea tunnel.
Last November, workers in Qingdao completed a subway tunnel reaching as deep as 288 feet under the surface of the Yellow Sea.
The chute measures five miles long, with 2.1 miles submerged under the sea. It is the longest and deepest undersea subway tunnel in China.
The Qingdao tunnel is about 100 feet deeper than the Bosphorus rail tunnel in Istanbul, which was previously reported to be the world's deepest underwater railway tunnel.
