Bouygues Construction, through its subsidiary Bouygues Travaux Publics, is collaborating with China Road and Bridge Corporation (CRBC) to build the Hong Kong East Drainage Tunnel (HKEDT). The contract, worth a total of €173 million, was awarded by the Drainage Services Department (DSD) of the Hong Kong Special Administrative Region Government.

Boosting Hong Kong’s climate resilience

This project was designed as part of the government’s policy to improve Hong Kong’s flood prevention infrastructure and strengthen the city’s resilience to extreme weather events.

Once completed, the tunnel will collect rainwater from upstream catchment areas and channel it to Pak Sha Wan, a nearby discharge point into the sea. This will relieve pressure on the existing downstream drainage network and reduce the risk of flooding in the Eastern District of the island, where impermeable surfaces and high urban density are significantly worsening the risk of flooding.

Cutting-edge underground engineering

The project includes the construction of a 3.6-kilometre drainage tunnel, approximately 5 metres in diameter, which will link the districts of Shau Kei Wan and Chai Wan, on the east coast of Hong Kong Island, to Pak Sha Wan. The consortium will also build seven intake structures to collect and capture surface runoff before it reaches built-up areas, six connection adits and an outfall structure which discharges water from the tunnel into the sea.

The construction of the tunnel will combine several techniques, including excavation using a tunnel boring machine (TBM), drill-and-blast excavation, the drill-and-break method for excavating rock and large concrete structures, and pipe jacking. This combination of techniques reflects the complexity of the project, which is scheduled for completion in 2030.

Established expertise in underground works

With more than 40 years of experience of designing and building tunnels on every continent, Bouygues Construction has expertise in all tunnelling techniques, from TBMs to traditional methods. These techniques are adapted to each geological and environmental context.

The company’s expertise has been demonstrated in landmark projects such as the Channel Tunnel and the Tuen Mun–Chek Lap Kok Tunnel in Hong Kong, which was excavated using a TBM with a 17.63-metre diameter, a world record in its category at the time. More recently, in the United States, the Pawtucket tunnels in Rhode Island and the Potomac River Tunnel in Washington D.C. also reflect the application of this expertise in the context of urban resilience: they both help to limit drainage system overflows during heavy rainfall and improve the quality of marine environments.