Creative Solution to Secure Critical Transportation Infrastructure on Emergency

Critical Transportation Infrastructure

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Protecting critical infrastructure isn’t just about preventing malicious attacks, but also mitigating the damage of natural disasters. Transportation infrastructure such as subway tunnels are at an inherent risk of being flooded with water.

The US Department of Homeland Security Science and Technology Directorate (S&T) has a solution in the form of a giant inflatable plug that will seal off subway tunnels and stop water from flowing throughout the subway system into stations and other subway lines.

While doing everything in their power to meet those requirements for the tunnel plug, the scientists and engineers also discovered other uses for the technology and developed additional tools needed to keep transit systems and citizens dry and safe during a terrorist attack or a natural disaster such as a mega storm.

“The tunnel plug is an innovative and groundbreaking technology that can protect subway tunnels from flooding,” said John Fortune, Program Manager in S&T’s Homeland Security Advanced Research Projects Agency (HSARPA).

Dubbed the Resilient Tunnel Plug (RTP), S&T, in conjunction with ILC Dover, the Department of Energy’s Pacific Northwest National Laboratory (PNNL), and West Virginia University, demonstrated the inflatable device at a recent event held in Frederica, Delaware. The uninflated plug integrates seamlessly into a subway tunnel without impeding the flow of normal train traffic, but can be quickly inflated to stop water from rushing through the tunnel and remain inflated to withstand the incredible pressure of restrained floodwaters.

According to, the plug needs to be stored in limited space while strong enough to withstand not just the external water pressure, but the internal pressure of the air inside the plug. This is what led the project team to use a high-strength fabric construction similar to the technology used to land the Mars Rover on the harsh planet surface.

“We tested several configurations of the plug during the program to eventually identify the design that worked best in the tunnel environment,” said David Cadogan, ILC Dover’s Director of Engineering and Product Development. “The most challenging aspects of the design, aside from having it withstand all of that pressure, was getting the plug to deploy and then seal the tunnel in a completely repeatable fashion. Then, finding the right design to allow it fit into a very small container mounted in the tunnel.”

The tunnel plug eventually passed its stress test by holding back water for a full 21 days.

“Spinoff technologies based on the plug, include covers for subway stairwells and fabric flood walls that can be deployed in an instant during an emergency. More than 20 stairwell covers have already been installed in lower Manhattan as part of the New York City subway system’s Super Storm Sandy recovery efforts,” said Fortune,