The US Department of Homeland Security’s Science and Technology Directorate tested an inflatable tunnel plug to contain flooding or harmful gases. The January test was undertaken in a dummy steel tunnel to see if the plug could hold back 35,000 gallons (159,113.2 litres) of pressurised liquids and gases.
The 5 by 10m cylinder was made out of a strong but flexible material comprising three layers: a thick webbing made of Vectran, a liquid crystal polymer; a second, non-webbed layer of Vectran and a third layer of polyurethane. Single-layer plugs failed early, scale model pressure tests.
Compactly positioned in tunnel sections to act as an airbag against floods, it can be rapidly inflated and then filled with water to make it sturdier. A design diameter greater than the tunnel id ensures a tight seal and envelopes irregularities in the lining, though too much material could create wrinkles that high-pressure water can traverse.
Further tests in 2012 will be undertaken with the future aim of marketing the device.
