The Resilient Tunnel Project came to the same marvelously simple conclusion that might have been suggested by a young child. When questioning the best solution for slowing the impact of underground flooding, it was decided that a giant tunnel plug was necessary to do the job. Really, it's brilliant.
What you see is an oblong inflatable ball that measures 32 feet in length and 16 feet in height and has a capacity of 35,000 gallons. It can be blown up in under half an hour from its deflated state and stored conveniently and compactly at just 20 inches thick against the subway tunnel wall. The DHS Science and Technology Directorate describes the Resilient Tunnel Project as a groundbreaking piece of equipment that could quite quickly inhibit the spread of water, fire and gas in the metro.
Photo Credits: silive