The scenes are remarkable. People had to wade through waist-deep water in the New York City subway earlier this month. This week in China, floodwater in Zhenghou trapped passengers in subway cars, per CNN. (Read their first-person accounts via the BBC.) The examples aren't as unique as you might think: Around the world, underground subway systems are seeing more and more instances of flooding during extreme weather, reports the New York Times. And municipalities are bracing for the problem to get worse. Coverage:
- The Times notes that many of these systems—including those in New York and London—were designed more than a century ago, and they are being overwhelmed by catastrophic flooding largely blamed on climate change. “It’s scary,” says transportation expert Sarah Kaufman of New York University. “The challenge is, how can we get ready for the next storm, which was supposed to be 100 years away but could happen tomorrow?”
- An assessment by the Regional Plan Association predicts that New York's subway system can expect more flooding in the coming years, reports Bloomberg. At least 20% of stations are at risk from storm surges, and the system in general is particularly vulnerable to "rain-induced flash floods."
- New York has poured millions into flood protection for the subways since Superstorm Sandy of 2012—including the installation of "flex gates" at entryways that can hold off flood water. But hurricanes and similar storms are relatively predictable. Less so are storms that dump vast amounts of rain in a short span, notes Curbed. That amounts to "chaotic evil," because water floods in unexpected places, as happened earlier this month.
- What to do? Protections are expensive, though "when you compare it to the cost of doing nothing, it starts to make much more sense,” an expert at a think tank tells the Times. Cities might also consider beefing up bike lanes and busing to handle overflow when floods shut down subways. Or perhaps even bringing trains above-ground permanently.
- Solutions also might require fundamental shifts in design. "Preventing subway flooding from dramatic rainfall ... requires a far more systemic approach than closing off station entrances in low-lying areas," writes Willy Blackmore at Curbed. "Instead of building a city that sheets off water, pushing it away as quickly as possible into storm drains, you need one that’s like a sponge and can soak up and retain rainfall where it lands."
(Read more New York City subway