The JV Dragages - Bouygues won the €1.15 billion contract for the construction of the Tuen Mun–Chek Lap Kok link (TM-CLKL) – northern connection sub-sea tunnel section. It’s a 4.2 km-long undersea twin-tube road tunnel in Hong Kong, each tube with two traffic lanes and 14 m in diameter. The tunnel will link the New Territories, north of Hong Kong, to Lantau Island, where the international airport is located. It will be bored 50 m below sea level. Two TBMs will be used.

The two tunnel tubes will be connected every 100 m by a total of 42 cross passages. Ground-freezing technology will be used to provide a watertight environment to enable these passages to be bored.

The project will entail working in an environment in which pressure is high (over 5 bar). Maintenance operations, particularly with respect to the cutting heads of the TBMs, will be carried out by teams of divers who will live in a hyperbaric base camp for four weeks at a time to allow them to deal with any issue that may arise at any time. The operation also includes the construction of two cut-and-cover approach tunnels of 530 m and 670 m respectively. Two ventilation buildings powered by wind energy will be constructed to the north and south of the tunnel. The works are scheduled to take more than five years (63 months): handover is scheduled for the end of 2018. Visit www.hyd.gov.hk and www.bouygues-construction.com. Contract number HY/2012/08. 37/13.