Giant Inflatable “Water Plug” Technology Protects Subway Tunnels from Flooding

Researchers at the Pacific Northwest National Laboratory (PNNL), in collaboration with ILC Dover and West Virginia University, have developed an innovative Resilient Tunnel Plug (RTP) to protect subway tunnels from catastrophic flooding. The project is supported by the U.S. Department of Homeland Security.

How It Works

• Made from Vectran® polymer fibers, which are significantly stronger and more water-resistant than conventional rubber.
• In emergencies, the inflatable plug can be deployed and fully inflated in under 12 minutes, sealing the tunnel completely.
• It can withstand water pressure of up to 11.5 psi, equivalent to several meters of water column.
• When not in use, it remains stored unobtrusively inside the tunnel, ensuring no disruption to regular train operations.

Why It Matters

This breakthrough represents a major step forward in protecting public transportation infrastructure and passenger safety against both natural disasters and unforeseen emergencies. By combining advanced materials and rapid deployment technology, the RTP could become a global model for resilient urban infrastructure.

Source: PNNL