Tuen Mun–Chek Lap Kok TBM

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 launched in June 2015 by Herrenknecht in Germany.^[2][3] The TBM was used to drill a 5 km tunnel connecting Tuen Mun to the Hong Kong International Airport, part of the Tuen Mun–Chek Lap Kok Link project. The contract for the project was around HK$ 18.2 billion (US$ 2.3 billion)^[4]

Mixshield S-880 "Qin Liangyu"
Classification	Tunnel boring machine
Application	Tuen Mun–Chek Lap Kok Link
Dimensions	Length: 120 metres (390 ft) Diameter: 17.6 metres (57.7 ft)
Weight	4,850 tonnes (4,770 long tons; 5,350 short tons)
Launched	2015
Cost	US$2.3 billion (2015) (equivalent to US$2.89 billion in 2023)[1] or HK$18.2 billion (2015)
Builder	Herrenknecht AG

Specifications

The machine had a diameter of 17.6 metres (57.7 ft),^[5] 0.1 metres (0.3 ft) more than Bertha, the previous largest tunnel boring machine.^[6][7] 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).^[3]

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.^[8]

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.^[3] The two 14-m TBMs broke through to complete the tunnels on 27 February 2019.^[3]

The tunnel boring project began in October 2018 after the cutterhead conversion and was completed by the end of 2020.^[9] Tuen Mun–Chek Lap Kok was disassembled after the completion of the tunnel.^[9]