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Giant inflatable plug could protect subways from floodwaters

Researchers test a giant inflatable plug that could protect subway systems from future flooding events.Department of Homeland Security

A giant inflatable plug that can be filled with 35,000 gallons of water at a moment’s notice could have prevented some of the flooding that crippled New York City’s transit in the wake of Sandy, according to an expert working on the technology.

This isn’t a case of Monday-morning quarterbacking. The technology is still in the lab. But the impact of this month’s superstorm on transit and the possibility that it’s a harbinger of things to come has focused attention on adding the plugs to the disaster-response toolbox.

“We don’t have a fully mature technology at this point … [but] assuming that these were installed at appropriate locations they would make a big difference,” Greg Holter, an engineer at the Pacific Northwest National Laboratory, who is working on the project, told NBC News.

The lab is partnering with the Department of Homeland Security, West Virginia University, and spacesuit manufacturer ILC Dover on development of the plugs to protect mass transit systems from terrorist attacks. It could also be used during severe weather events, Holter said.

The plug inflates with water or air to dimensions of roughly 32-feet long and 16-feet wide. It holds 35,000 gallons, about the amount of water in a typical backyard swimming pool.

The plug is slightly larger than the tunnel itself, allowing it to envelop irregularities and conform to the existing space.Department of Homeland Security

It is designed to envelope irregularities in a subway tunnel such as pipes, tracks and ventilation ducts when inflated to create a tight seal and is strong enough to hold back high-pressure floodwaters.

The outer layer of the plug is webbing made from the high-tech material Vectran, a liquid-crystal polymer fiber. Additional layers of non-webbed Vectran and polyurethane add strength and sealing properties.

The technology could be ready for deployment within a year or two, Holter said. For now, tests are continuing. “You want to be sure that the thing works properly the first time and works quickly,” he noted.

For protection against sudden terrorist attacks, the plugs need to be stored strategically in subway tunnels. In the case of severe weather events such as Sandy, a few days advanced warning would be sufficient to place mobile units where they would offer the greatest protection, Holter noted.

The plugs are expected to cost about $400,000 each, which is real money for strapped public transit systems. Given the prospects for a stormier future, finding the funds might be prudent.

Holter cautioned that the plugs alone are insufficient to stop all floodwaters from getting into subway systems — think ventilation shafts and stations that get flooded from water on the streets — "but nevertheless, this could make a big difference."

 via International Herald Tribune 

John Roach is a contributing writer for NBC News Digital. To learn more about him, check out his website. For more of our Future of Technology series, watch the featured video below.