NYC’s Subway Flooding Isn’t A Fluke. It’s The Reality For Cities In A Warming World

НОВОРОССИЯ.RU
02 Сен 2021, 18:47

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Rescuers carried a boat into the subway in Zhengzhou, China in July after flash floods trapped passengers underground.

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But keeping the water out is a constant battle. Much of Washington, D.C.’s metro system was built nearly 50 years ago, and the subways in New York City and Boston are even older. Air vents are flush with the sidewalk or street, which makes it easy for water to flow in. Many station entrances are in low-lying places, or are constructed in ways that funnel water from the street down stairs or escalators.

«Older systems were designed for the climate of the past,» says Tina Hodges, a former analyst at the Federal Transit Administration who wrote a 2011 report about climate risks to public transit in the U.S. «In the Northeastern United States, which is home to some of the oldest and largest transit systems in the country, there’s already been a 67% increase in the heaviest precipitation.»

The same is true in many European cities, including London and Berlin. In recent years, passengers have captured strikingly similar videos of water cascading into subways stations in cities thousands of miles apart.

Newer subway systems in flood-prone parts of Asia may offer clues about how to adapt. As this summer’s disaster in Zhengzhou made clear, Asian cities are on the front lines of climate-driven subway flooding. And the fact that those newer systems are often better protected from flooding and fatalities underscores the urgency of adaptation.

Water runs down the steps of a subway station in Berlin, Germany in 2019. Cities in the U.S. and Europe are racing to waterproof older subway systems as climate change drives more rain.

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«There’s a lot to learn from Asian cities, ways to deal with flooding of underground trains,» he says. For example, in Taipei, where flooding from cyclones is common, Taiwanese authorities raised the entrances to stations to keep water out. In Kyoto, Japan, researchers built a full-scale model of a subway station escalator and simulated a flash flood to see how much water people could safely walk through, and to help create emergency plans for closing stations during storms. Bangkok, Thailand, has long had a flood warning system to keep passengers safe, although the city has struggled to prevent underground train flooding.

Many subway systems in Asia were also built more recently than their counterparts in the U.S. and Europe, so they are better-suited to the current climate, says Djordjevic.

In the U.S., larger U.S. cities are generally doing a better job adapting to and preparing for transit flooding than smaller cities because they have more resources, says Hodges. For example, large transit departments increasingly employ resilience experts who work full-time on adaptation, and can also collaborate with climate scientists and engineers to come up with solutions that protect trains and passengers from flooding. Smaller cities are less likely to have such resources.

«There are definitely barriers to adapting to climate change, one of which is that it’s just difficult to interpret the information that comes in from climate scientists into actionable information that planners and engineers can use,» Hodges says.

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Heavy rain from remnants of Hurricane Ida flooded much of the New York City subway system. Authorities issued a travel ban and warned residents to avoid stations.

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Heavy rain from remnants of Hurricane Ida flooded much of the New York City subway system. Authorities issued a travel ban and warned residents to avoid stations.

David Dee Delgado/Getty Images

Despite flood risk, new train tunnels are still an attractive option

The benefits of underground trains still outweigh the costs for many cities. Since Hurricane Sandy, New York City has pressed forward with subway line expansions. San Francisco is expanding its subway, even as the system faces flooding from sea level rise.

Fort Lauderdale, one of the most flood-prone places in the country, is considering a new underground train line that would reduce car traffic and allow residents to commute into the downtown area by train.

Investing in new underground infrastructure in a city known as the «Venice of America» has raised some eyebrows. The editorial board of the city’s paper spoke out against the plan, and argued that the train should cross a major river in the city via a bridge, rather than a tunnel.

But while Mayor Dean Trantalis acknowledges that climate-driven flooding is a concern in his city, he dismisses concerns about train tunnel flooding. «If you put in the proper pump stations and the proper technology to anticipate heavy rainfalls and things like that — I’ve lived in Fort Lauderdale for almost 40 years and I’ve never once seen our tunnel flooded,» he says. And keeping the train underground will alleviate traffic congestion caused by railroad crossings.

Experts say it’s important that new infrastructure take into account the costs of maintenance and the climate of the future. Sea level rise is accelerating in many places, including Florida. If new train systems are designed to last 30 years or more, they will need to withstand dramatically higher tides, as well as more frequent and severe storms.

«When it comes to coastal areas or parts of Florida, sooner or later sea level rise will lead to some areas that need to be abandoned or protected at a very, very high cost,» says Djordjevic. «So those decisions would need to be looked at very carefully.»