Authorities in the northeastern U.S. investigating flood-barrier technologies to block future flooding in subway tunnels have high hopes for one new device. A pressurized tunnel plug, tested this month, offers a lower price and quicker installation than competing, proven technologies.

西弗吉尼亚大学（WVU）机械和航空航天工程教授Ever Barbero说：“我一开始称其为一个巨大的安全袋。”Barbero称他的国土安全部（DHS）研究合同为“高风险，高额付费提案”。在现场测试中，风险是32英尺长的“安全气囊”会失败。成功将意味着全国范围内针对极端天气事件或恐怖袭击的额外衡量标准。

"There are over 30 under-river tunnels nationwide," says John Fortune, project manager for DHS' Science and Technology Directorate. "We wanted a novel technology and new approach to solve this problem." The problem, as thousands of citizens and commuters around New York City found out, is tunnel flooding. With high payoffs in mind, Barbaro and WVU developed the 2,000-lb pressurized stopgap for tunnels.

"Existing floodgates have drawbacks like heavy costs and lengthy installations," says Fortune. Each existing tunnel flood barrier requires a singular design, he says. "We wanted a cheaper, more flexibly deployed strategy that would be customizable on a tunnel-by-tunnel basis," says Fortune. The price ceiling for a tunnel plug is $400,000, says Barbero. He thinks the unit cost will drop as the plug, manufactured by materials company ILC Dover, Frederica, Del., moves beyond the testing phase.

The plug, designed by DHS, ILC Dover, the Pacific Northwest National Lab and West Virginia University, is based on three critical criteria. The plug had to be strong enough to withstand a tunnel full of highly pressurized water. It had to be small enough to fit into a storage container whose size wouldn't disrupt daily tunnel traffic. Finally, the container and the plug itself had to be able to deploy reliably and remotely every time.

Barbero说：“插头由三层制成，其中两层是Vectran，这是一种类似于Kevlar的[聚合物合成]织物，只有更灵活，更坚固。”内层是聚氨酯和尿氨基烷膀胱，该膀胱构建为插头内部的空气或水。该层在膨胀的袋中承受压力，以通过摩擦在隧道的内部将其固定在适当的位置。第二个Vectran层保护膀胱。Barbero说，外壳是Vectran织带的“篮子编织”，可提供强度和穿刺性。

Fortune说，编织织物的冗余确保了，如果壳的单点失败，膀胱将保持膨胀。容器单元也由Vectran制成。经过重复测试，以确保插头在需要时正确展开。

Barbero说：“插头必须能够填充轨道，管道和第三条轨道的轮廓”，而不会泄漏更多的水。

该插件正在与经过验证的洪水级防御系统竞争。由鹿特丹大学和咨询工程师Arcadis测试的一种系统是贝内克斯洪水防御系统的自我关闭洪水屏障。这是嵌入地面中的墙壁，由于洪水泛滥到下面的腔体时，它会自动上升（无电力）。该系统目前保护华盛顿特区的国家档案馆大楼以及世界上其他建筑物。它尚未用于阻挡隧道，但目前正在英国的80个地铁站安装。