Tunnel flood woes any ideas?

12 August 2021


This month, in Zhengzhou, China, at least four people died when a road tunnel almost completely filled with water following a record 624mm of rain in 24 hours. During the same weather event in that city, a subway tunnel was deluged, with commuters up to their knees in water. In London, less dramatically but equally worrying, torrential rain and flash flooding put at least two stations out of action. And there are other instances elsewhere.


Climate change is seen as being behind these unusual weather events – accompanied by extreme temperatures, drought and forest fires globally.

What is becoming eerily clear is that these events, far from being ‘one in a hundred year’ occurrences, look set to become more frequent. Measures need to be taken to safeguard installations from future disasters. Not siting infrastructure in a flood plain is a start but that only applies to new work. Clearly infrastructure – and tunnels especially – need more robust and innovative protection. Malaysia’s SMART tunnel provides an innovative approach to the problem.

Can automatic barriers be used to seal-off tunnels? Perhaps workable in some cases but not all – a motorway tunnel would have to close as a result. Sustainable urban drainage (SuDS) is advanced as a possible solution and while potentially effective for general flood mitigation, could it cope with the sudden, sustained and extreme deluges that have been witnessed recently? So, what can be done?.

We don’t know but you might. We want to hear your ideas on how tunnel flooding can be prevented, or mitigated, to avoid the disturbing scenes we have seen recently.

So, in no more than 500 words, plus a sketch or two (if needed), readers of T&TI are invited to submit their innovative, original but practical solutions on how to prevent catastrophic flooding in tunnels, whether metro, road or rail. The best will be published within these pages as part of a future feature. Email your ideas to [email protected] to arrive no later than 1 September.

I look forward to delving into your innovative ideas.

George Demetri Editor