Hurricane Sandy revealed just how vulnerable much of America's infrastructure is to flooding and other catastrophes, but the Department of Homeland Security is working on a solution that could protect subways and tunnels: balloons. The New York Times takes a look at a project overseen by the DHS's Science and Technology Directorate, which hopes to use large, inflatable plugs to prevent future flooding in underground tunnels. While still in the testing phase, the program has the potential to be both cheaper and easier to deploy than more complex options like floodgates. Check out the source link below for the full story — and to see one of the tests in action.