If an ounce of prevention is worth a pound of cure, a new technology developed by the Department of Homeland Security might have been worth its weight in gold during Hurricane Sandy.

That technology is a gigantic inflatable plug that might have prevented the massive flooding of New York City's subway system caused by the storm. In simulations, the plugs--originally developed to combat terrorist attacks and now being evaluated at West Virginia University--have proven to be effective at limiting flooding in tunnels.

Developed as part of the "Resilient Tunnel Project," the plugs are actually enormous balloon-like capsules, according to a department press release. When filled with air or 35,000 gallons of water, the plugs measure 32 feet by 16 feet. Unfilled, they take up little space and can be stashed throughout tunnels, waiting to be inflated remotely at a moment's notice.

They're tough, too. The plug's engineering uses the same design and manufacturing processes as space suits and inflatable space habitats.

PHOTOs of the plug, via DHS and West Virginia University:
hurricane sandy subway plug

"We've proved that these plugs can hold back water," Dave Cadogan of ILC Dover, the plug's manufacturer, told CNN. "I wish we had moved a little bit faster as a team and had gotten this development done."

Other brains behind the project told CNN only one current-generation plug has been manufactured, and the project is at least two years away from producing and selling them to transit agencies.

New York City shut its subway system in advance of Hurricane Sandy, and though service was partially restored Thursday, officials so far have been reluctant to offer a timetable for returning to normalcy after the system sustained "an unparalleled level of damage."

Transit officials estimate the New York subway system loses $18 million every day it's out of order.

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  • US-WEATHER-STORM-SANDY

    Passengers crowd onto a bus on First Avenue October 31, 2012 in New York. There was limited bus service in New York while the subway system was still not functioning after being flooded by Hurricane Sandy. AFP PHOTO/Stan HONDA (Photo credit should read STAN HONDA/AFP/Getty Images)

  • US-WEATHER-STORM-SANDY

    A man rides a skateboard down First Avenue October 31, 2012 in New York as subway service is still suspended due to Hurricane Sandy. AFP PHOTO/Stan HONDA (Photo credit should read STAN HONDA/AFP/Getty Images)

  • US-WEATHER-STORM-SANDY

    Passengers crowd onto a bus on First Avenue October 31, 2012 in New York. There was limited bus service in New York while the subway system was still not functioning after being flooded by Hurricane Sandy. AFP PHOTO/Stan HONDA (Photo credit should read STAN HONDA/AFP/Getty Images)

  • US-WEATHER-STORM-SANDY

    Passengers crowd onto a bus on First Avenue October 31, 2012 in New York. There was limited bus service in New York while the subway system was still not functioning after being flooded by Hurricane Sandy. AFP PHOTO/Stan HONDA (Photo credit should read STAN HONDA/AFP/Getty Images)

  • US-WEATHER-STORM-SANDY

    Passengers negociate with a taxi driver on First Avenue October 31, 2012 in New York. Yellow cabs were allowed to pick up multiple fares due to limited public transportation as a result of Hurricane Sandy. AFP PHOTO/Stan HONDA (Photo credit should read STAN HONDA/AFP/Getty Images)

  • US-WEATHER-STORM-SANDY

    A woman tries to hail a taxi on First Avenue October 31, 2012 in New York. Yellow cabs were allowed to pick up multiple fares due to limited public transportation as a result of Hurricane Sandy. AFP PHOTO/Stan HONDA (Photo credit should read STAN HONDA/AFP/Getty Images)

  • Motorists sit in heavy traffic while crossing the Robert F. Kennedy Triboro Bridge during the morning rush, Thursday, Nov. 1, 2012, in the Queens borough of New York. The floodwaters that poured into New York's deepest subway tunnels may pose the biggest obstacle to the city's recovery from the worst natural disaster in the transit system's 108-year history. (AP Photo/Jason DeCrow)

  • Early morning traffic in Brooklyn moves slowly beneath the Manhattan skyline, Thursday, Nov. 1, 2012 in New York. Commuting is a headache for New Yorkers as many subways and tunnels are out of order following superstorm Sandy. New York City moved closer to resuming its frenetic pace by getting back its vital subways Thursday, three days after a superstorm, but neighboring New Jersey was stunned by miles of coastal devastation and the news of thousands of people in one city still stranded by increasingly fetid flood waters. (AP Photo/Mark Lennihan)

  • Joseph Leader, Metropolitan Tranportation Authority Vice President and Chief Maintenance Officer, shines a flashlight on standing water inside the South Ferry 1 train station in New York, N.Y., Wednesday, Oct. 31, 2012, in the wake of superstorm Sandy. The floodwaters that poured into New York's deepest subway tunnels may pose the biggest obstacle to the city's recovery from the worst natural disaster in the transit system's 108-year history. (AP Photo/Craig Ruttle)

  • Morning commuters ride a downtown-bound, west side subway train toward New York's Times Square, Thursday, Nov. 1, 2012. New York City moved closer to resuming its frenetic pace by getting back its vital subways Thursday, three days after a superstorm, but neighboring New Jersey was stunned by miles of coastal devastation and the news of thousands of people in one city still stranded by increasingly fetid flood waters. (AP Photo/Richard Drew)

  • Passengers exit a downtown-bound, west side subway train in New York's Times Square, Thursday, Nov. 1, 2012. New York City moved closer to resuming its frenetic pace by getting back its vital subways Thursday, three days after a superstorm, but neighboring New Jersey was stunned by miles of coastal devastation and the news of thousands of people in one city still stranded by increasingly fetid flood waters. (AP Photo/Richard Drew)

  • Early morning traffic in Brooklyn moves slowly beneath the Manhattan skyline, Thursday, Nov. 1, 2012 in New York. New York City moved closer to resuming its frenetic pace by getting back its vital subways Thursday, three days after a superstorm, but neighboring New Jersey was stunned by miles of coastal devastation and the news of thousands of people in one city still stranded by increasingly fetid flood waters. (AP Photo/Mark Lennihan)

  • The sun rises behind the Empire State Building in New York on Thursday, Nov. 1, 2012. New York City moved closer to resuming its frenetic pace by getting back its vital subways Thursday, three days after a superstorm, but neighboring New Jersey was stunned by miles of coastal devastation and the news of thousands of people in one city still stranded by increasingly fetid flood waters. (AP Photo/Peter Morgan)

  • People wait at a bus stop on Second Avenue between East 23rd Street and East 22nd Street in New York Wednesday, Oct. 31, 2012. With the city's subways knocked out of service by superstorm Sandy, and a reduced number of city buses operating, New Yorkers are scrambling to commute to work. (AP Photo/Tina Fineberg)

  • Passengers wait for a chance to squeeze into an overcrowded city bus, Wednesday, Oct. 31, 2012, in New York. With the city's subways knocked out of service by superstorm Sandy, and a reduced number of city buses operating, New Yorkers are scrambling to commute to work. (AP Photo/Mark Lennihan)

  • Passengers squeeze into an overcrowded city bus, Wednesday, Oct. 31, 2012, in New York. With the city's subways knocked out of service by superstorm Sandy, and a reduced number of city buses operating, New Yorkers are scrambling to commute to work. (AP Photo/Mark Lennihan)

  • This photo provided by Metropolitan Transportation Authority shows people boarding a bus, as partial bus service was restored on Tuesday, Oct. 30, 2012. Mass transit, including buses, was suspended during Sandy, the storm that made landfall Monday. (AP Photo/Metropolitan Transportation Authority, Patrick Cashin)