The Tuen Mun - Chek Lap Kok TBM otherwise known as Qin Liangyu or more formally, the Mixshield S-880 was the world's largest

tunnel boring machine A tunnel boring machine (TBM), also known as a "mole" or a "worm", is a machine used to excavate tunnels. TBMs are an alternative to drilling and blasting methods and "hand mining", allowing more rapid excavation through hard rock, wet or dry so ...

launched in June 2015 by

Herrenknecht Herrenknecht AG is a German company that manufactures tunnel boring machines (TBMs). Headquartered in Allmannsweier, Schwanau, Baden-Württemberg, it is the worldwide market leader for heavy TBMs. Established by Martin Herrenknecht in 1975, the ...

in Germany. The TBM was used to drill a 5 km tunnel connecting

Tuen Mun Tuen Mun () or Castle Peak is an area near the mouth of Tuen Mun River and Castle Peak Bay in the New Territories, Hong Kong. It was one of the earliest settlements in what is now Hong Kong and can be dated to the Neolithic period. In the mo ...

to the

Hong Kong International Airport Hong Kong International Airport is an international airport on the island of Chek Lap Kok in western Hong Kong. The airport is also referred to as Chek Lap Kok International Airport or Chek Lap Kok Airport, to distinguish it from its predec ...

, part of the

Tuen Mun–Chek Lap Kok Link The Tuen Mun–Chek Lap Kok Link (, abbreviated as TM–CLKL) is a road project in the New Territories, Hong Kong. It comprises two elements: the "Northern Connection" and the "Southern Connection". The Northern Connection comprises an undersea t ...

project. The contract for the project was around HK$ 18.2 billion (US$ 2.3 billion)

Specifications

The machine had a diameter of , more than

Bertha Bertha is a female Germanic name, from Old High German ''berhta'' meaning "bright one". It was usually a short form of Anglo Saxon names ''Beorhtgifu'' meaning "bright gift" or ''Beorhtwynn'' meaning "bright joy". The name occurs as a theonym, s ...

, the previous largest

. Outside of its cutting diameter, it had an overall length of 120 metres (393 ft 8 in) and weighed 4,850 tonnes (5,346 US-tons).

Operations

The machine would excavate a 5 km-long underwater tunnel, working at pressures as high as 5 bars. The drilling had taken place in depths of up to 50 m below sea level. By 25 March and 3 November 2015, the TBM's shield was converted into one the much smaller 14-m to complete the rest of the tunnel alongside another Herrenknecht TBM. The two 14-m TBMs broke through to complete the tunnels on 27 February 2019. The tunnel boring project began in October 2018 after the cutterhead conversion and was completed by the end of 2020. Tuen Mun–Chek Lap Kok was disassembled after the completion of the tunnel.

References

{{DEFAULTSORT:Tuen Mun-Chek Lap Kok TBM Tunnel boring machines