It's safe to say images of New York's subway system flooded with water from Hurricane Sandy's storm surge shocked everyone. With the tracks deep underwater days after the storm causing travel mayhem in the city, many have asked if this is something that could have been prevented? Hindsight is 20/20, but the truth is giant inflatable plugs actually have been in development and testing to prevent just such a flooding.
The Department of Homeland Security (DHS) has been working on the "Resilient Tunnel Project" as a cheap alternative to floodgates or doors for the subway system, but only had one prototype plug when the storm hit. The giant 32″ x 16″ plug can hold up to 35,000 gallons of air or water and when inflated it seals off a tunnel entrance.
The DHS has been working with of the Pacific Northwest National Laboratory, West Virginia University (WVU) and ILC Dover, the company that makes NASA's space suits. The plug, at its most basic is made with the same process and the same webbings and layers of cloth from space suits and inflatable space habitats.
The first round of pressurized testing of the inflatable plugs failed to form a seal, so the team was forced to rethink the design. They decided on three-layers — one of them being made from Vectran, a liquid-crystal polymer fiber that looks like a thick and tightly woven cargo net. The other two layers were made of non-webbed Vectrane and polyurethane.
In addition to changes in the composition of the bag, engineers also designed it to have a circumference larger than a tunnel entrance — this way, after inflation the plug is sure to form a tight seal. This design worked during inflation and flooding tests in a specifically designed test tunnel back in January. Ironically, further testing is set to begin next week.
Even though the giant plugs are only in the testing stage with a ways to go before they are ready, the team expressed regret they couldn't have done anything for Hurricane Sandy.
"We've proved that these plugs can hold back water," said Dave Cadogan of ILC Dover, told Inhabitat. "I wish we had moved a little bit faster as a team and had gotten this development done."
The team believes if they had deployed bags in the tunnels under the East River they might have been able to stop some of the flooding; what they can't stop is the water seeping in through pourous ground in parts of the tunnels.
It's laudable the team wishes they could have had the bags ready for Sandy, but clearly there are massive logistics that still need to be addressed before such a system could be deployed even when the bags are perfected.
The fact they are so far along with the concept should bring some comfort to New Yorkers. Sandy opened a lot of eyes as to the damage storm surges can cause — so while we didn't expect to see so much gushing water in the tunnels this time — we'll know what can happen next time.
The exact timetable for further testing and eventual deployment of the plugs via the DHS is unknown, but it's good to know the team is working on them.