DHS Testing Specialized Plug to Contain Subway Fires
The plug is essentially a giant beach ball that drops from the ceiling and inflates inside a subway tunnel. It seals off the entire passageway and, ideally, prevents smoke or fire from expanding.
The project also aims to protect against flooding, chemicals and other hazards, said the Department of Homeland Security’s directorate for science and technology.
The tunnel plug program is funded by the homeland security advanced research projects agency within the Department of Homeland Security’s science and technology directorate.
Researchers first tested much smaller plugs in a scale model transit tunnel. Based on those experiments, a design was selected for a full-scale device. A prototype was built and a model of a mass transit tunnel was constructed for further testing at West Virginia University last spring and summer.
More testing was done in August in an actual mass transit tunnel through a partnership with the Washington Metropolitan Area Transit Authority, which serves Washington, D.C. and the surrounding areas.
The plug was activated and completely inflated in three minutes. After it enlarged to its full size, a smoke generator was used to determine if any smoke could seep between the wall and the device.
Observers looked for smoke flowing from the sides as an indicator of areas that had not been completely sealed. For the most part, the tunnel plug worked, although there was significant leakage around one spot in which it had touched a pipe sticking out of the tunnel wall, DHS said.
Improvements are planned in preparation for later tests. Future research will also focus on strengthening the plug and adapting its design for different scenarios.
It is still in the early development stages, so it is premature to say whether any city government will adopt it, said John S. Verrico, spokesman at the DHS science and technology directorate.