Tunnel Plug

[Image: The plug, courtesy of Homeland Security's Resilient Tunnel Project, via Wired UK].

The U.S. Department of Homeland Security's "Resilient Tunnel Project" has come up with a prototype 35,000-gallon "plug," or "enormous inflatable cylinder," in the words of PhysOrg.com, one that is "tunnel-shaped with rounded capsule-like ends" and "can be filled with water or air in minutes to seal off a section of tunnel before flooding gets out of control."

The idea is to prevent underground floods from taking down whole subway systems or otherwise destroying subterranean logistical networks, such as telecom cables (or Chicago's infamous abandoned coal-delivery tunnels).

The plug itself is made from tear-resistant fabrics—including liquid-crystal polymers—that can expand around irregular surfaces and objects, producing, in effect, an impassable blockade. As Wired UK points out, this means the plug could also be used as a quarantine barrier, stopping the passage of chemical or biological agents.

On an unrelated note, meanwhile, I'm looking forward to receiving a review copy of The Insurgent Barricade by Mark Traugott next week, and, in the context of that book, this "enormous inflatable cylinder" could take on other, aboveground roles, such as intervening in and impossibly redirecting urban movement (both in the name of security and insurgency). To put this in somewhat absurd terms, what might the Paris Commune have looked like, for instance, had its participants used giant, knife-proof inflatable objects, like revolutionary sausages blocking access to whole streets?

[Image: Paris barricade made from cobblestones (1871), photographed by Pierre-Ambrose Richebourg, via Wikipedia].

In any case, whether or not these or other such "plugs" will be permanently installed, like automotive airbags, inside underground infrastructure is yet to be decided; but it seems quite likely that affordably fabricated, inflatable barriers will become regular architectural safety features of a subterranean system near you.