When Hurricane Sandy struck New York City a few weeks ago, seven of the 14 under-river subway tunnels flooded as a result of the storm surge, halting operation of some subway lines for more than a week. One possible future safeguard for this kind of disaster: huge, inflatable tunnel plugs. At the University of West Virginia, researchers working with the Department of Homeland Security are testing a massive balloon made of high strength material that could potentially be used to plug subway tunnels during future calamities–be they weather- or terrorism-related–keeping water out and important infrastructure functional. Catch a video of this technology inflating over at the NYT.