25 September 2013
France’s Bouygues Construction, through two subsidiaries, has won a $2.3bn contract to build undersea road tunnels in Hong Kong.
The contract is the largest design-build contract ever awarded in the country, and requires ‘saturation diving’ techniques.
Dragages Hong Kong and Bouygues Travaux Publics will be responsible for the design and construction of two sub-sea tunnels, each approximately 14m in diameter and 4.2km long, linking the New Territories region to Lantau Island, the location of Hong Kong’s international airport.
To facilitate maintenance works and for emergency escape, these two tunnels will be connected by 42 cross passages at 100m intervals.
Lantau Island will be linked to the New Territories region by underground tunnels (Wikimedia Commons)
Most of the work will be undertaken in a compressed air environment and, for maintenance work on the cutter heads of the tunnel boring machines, Dragages-Bouygues will adopt a ‘saturation diving’ technique.
This means that saturation divers will stay for four weeks at a time in specially designed habitats and will be required to undergo only one decompression every four weeks rather than a decompression every day.
The project is scheduled for completion in 2018.