Name and Location
Undersea road tunnel project, Hong Kong.

Client
Government of Hong Kong.

Project Description
The project comprises the design and construction of a 4.2 km undersea road tunnel.

The project involves building a twin-tube tunnel, with each tube being 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 tunnel boring machines (TBMs) will be used. The two tunnel tubes will be connected every 100 m by 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, at more than 5 bar. Maintenance operations, particularly 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. This new method of organisation avoids them having to undergo decompression too frequently.

The operation also includes the construction of two cut-and-cover approach tunnels of 530 m and 670 m, as well as two ventilation buildings powered by wind energy.

Value
€1.15-billion.

Duration
Handover is scheduled for the end of 2018.

Latest Developments
Bouygues Construction, through two of its subsidiaries – Dragages Hong Kong and Bouygues Travaux Publics has won a contract for the construction of the undersea road tunnel.

Two innovations developed by Bouygues – Mobydic and Snake – will be used at the project to reduce the need for manual operations in hyperbaric conditions.

Mobydic – a system of sensors incorporated into the disc cutters in the heads of the TBMs, will make it possible to permanently monitor the state of wear of the cutters, while allowing real-time geological mapping of rock phases.

Snake, a remote-controlled exploration arm equipped with a high-pressure jet, will clean the TBM heads and eliminate clogging to enable inspection of the heads.

Key Contracts and Suppliers
Bouygues Construction (construction).

On Budget and on Time?
Not stated.

Contact Details for Project Information
Bouygues Construction media contact, Jean-Luc Letouzé, tel +33 1 30 60 55 05 or
email jl.letouze@bouygues-construction.com.