A huge inflatable plug was tested by the Department of Homeland Security to stop subway tunnels from flooding.
Credit: Department of Homeland Security
What could have stopped New York City's huge system of subway tunnels from flooding during Hurricane Sandy? Perhaps a giant inflatable plug that successfully held back simulated flooding during a test by the Department of Homeland Security.
The huge plug holds 35,000 gallons of air or water — equal to a medium-size backyard swimming poll — when it inflates to seal off a subway tunnel entrance. But project managers expressed regret that they had only created one prototype by the time Hurricane Sandy hit and filled up New York subway tunnels with water, according to a CNN report. They added that the project needed at least two more years before they could begin marketing the tunnel plugs.
The Department of Homeland Security Science (DHS) and Technology Directorate envisioned the Resilient Tunnel Project as a cost-effective way to prevent subway flooding without installing expensive floodgates or doors. DHS enlisted the help of the Pacific Northwest National Laboratory, West Virginia University (WVU) and ILC Dover — a longtime maker of NASA space suits.
"We used the same design and manufacturing techniques we use in space suits and inflatable space habitats," said Dave Cadogan, director of engineering at ILC Dover. "The webbings and underlying layers form a tough barrier that is strong and resilient to damage."
One of the first full-scale prototypes failed during pressurized testing. That compelled the project team to settle on a three-layer design that includes Vectran, a liquid-crystal polymer fiber resembling a thickly woven cargo net, as well as two additional layers of non-webbed Vectrane and polyurethane.
Engineers also designed the plug to have a circumference bigger than a subway tunnel entrance as a way of ensuring a tight seal. The second prototype proved itself worthy during inflation and flooding tests at a specially-built test tunnel in Morgantown, WV in January.
New Yorkers who spent days without subway service may wish the project had been born sooner. But if subsequent tests go well, New York City's MTA and public transit systems all around the U.S. may be glad to have the giant plugs for future superstorms.