With the threat of terrorism and seas both rising, the Department of Homeland Security is worried about car and subway tunnel safety. For the last 10 years, they’ve been brainstorming different technologies to protect tunnels in the event of a catastrophe.
And they’ve found a way, teaming up with a company from rural Delaware.
The Department of Homeland Security and ILC Dover on Tuesday showed off a giant, inflatable structure designed to stop flooding in tunnels.
The resilient tunnel plug sits on a shelf on the side of a subway tunnel. It’s only about 5 feet tall.
But when deployed, it can inflate to more than 32 feet long and 16 feet in diameter, filling a tunnel. It seals off a portion to prevent water from flooding to other parts of the system.
“So when the water comes, it’s pushing on one end of the plug, but the air pressure inside is pushing against the walls of the tunnel,” said Jeff Roushey, ILC Dover’s senior product engineer.
The tunnel plug takes about 12 minutes to inflate to full pressure. It’s set up to stop water from coming up from the bottom and flooding a tunnel. Roushey said when water breaches a tunnel, the tunnel plug isolates it before the entire system is lost.
“Depending on the size of the hole in the tunnel and the depths of the river — and everything else that you’re in — the whole system can go down because they’re all linked together,” Roushey said.
Taking on the technology was a different kind of mission for ILC Dover, which typically manufactures textiles and coated fabrics, said Dave Cadogen, the director of product development at ILC Dover.
“For flood protection, what we’re able to do is pack these materials into very small volumes, whereas if you were to try and solve this problem with metal, it would take a lot of material to do the same job that a fabric wall can be used to close off the same sort of opening,” Cadogen said.
With property and infrastructure damage provoked by climate change and rising seas, Cadogen said the tunnel plug could be used anywhere.
“We’re just offering this to anybody and everybody to protect any type of building that’s out there,” Cadogen said.
And in a terrorist situation, the tunnel plug could block toxins, for example, from traveling through.
“It’s really critical to contain the event as quickly as possible to save property but also save lives,” said John Fortune, the Department of Homeland Security’s program manger of DHS Science and Technology Directorate.
Fortune said when the DHS first came up with the idea for a tunnel plug, a lot of people didn’t think it would work.
“And it’s not been all successes,” Fortune said. “There’ve been different designs, some have worked, some have not worked at all. So we’ve taken our lessons, built better each time, and then come up with the design you see today.”
They worked with ILC Dover, the Department of Energy’s Pacific Northwest National Laboratory and West Virginia University to develop the product since 2007. The latest design, made of high-strength manufactured fibers called Vectran, has proven to be successful in testing, Fortune said.
If a transit agency or a city wanted to install a resilient tunnel plug, they would need to work with ILC Dover to determine the best way to install it - likely modifying a tunnel to fit the plug.