MTR trains passes beneath Hong Kong’s Victoria Harbour through four immersed tube tunnels – but should one of these tunnels be breached, massive flood gates are ready to be deployed, to protect the rest of the network.
They hide inside ventilation structures located beside the harbour.
Marking the transition between the immersed tube and bored sections of tunnel.
The engineering inside them quite complex.
Utilitarian function meets sculptural form at the Kowloon Ventilation Building (KVB), the first structure built on the West Kowloon waterfront. An underground railway depends on numerous supporting services typically housed in buildings more about function than flourish. But this prominent site on reclaimed land, highly visible from Hong Kong Island, demanded a different approach.
Sitting at the northern end of an undersea tunnel linking Central to the new Chek Lap Kok Airport, the KVB unites a technically complex brief within one unified, cost-effective, yet architecturally exciting building.
Aside from its eponymous purpose of ventilating the rail tunnels, the KVB houses a multitude of ancillary facilities including floodgates to protect the underground system, power supply, emergency access and egress, pumping and filtration systems for a seawater cooling system, and train sidings. Only one-third of the building is visible. The rest sits within a massive excavation that extends down to the tunnels.
And are tested regularly.
The 80-ton electrically operated flood gates at the West Kowloon can be deployed in two minutes, and is linked to the signalling system to prevent trains from approaching the blockage.
Similar gates are fitted to the Tsuen Wan line tunnel at Tsim Sha Tsui.
And six sets of flood gates are being installed on the new Shatin to Central Link tunnel.
They sure dwarf the flood doors found at MTR station entrances!
And the other tunnel?
I assume that the Eastern Harbour Crossing also has floodgates protecting the rail network, but I can’t find any further detail.
- The Airport Railway photo essay by Raymond Wong
- The Construction of Recent Tunnels in Hong Kong by Raymond Wong
- Ventilation Buildings, Shatin to Central Link (HUH-ADM) EIA Report
A foreign footnote
Here we see a flood door being closed inside a Russian metro tunnel – possibly on a brand new section of railway, given how clean the tunnel is.