The world's longest undersea tunnel used specialized air seals to prevent deep-sea flooding
Japan's Seikan Tunnel, the world's longest undersea passage, utilized cutting-edge air pressure seals to protect workers and trains from the crushing depths of the Tsugaru Strait.
Opening on March 13, 1988, the Seikan Tunnel remains an engineering marvel, stretching 53.85 kilometers with nearly half of its length deep beneath the seabed. To prevent catastrophic flooding at depths of 240 meters, engineers developed specialized air pressure seals and utilized 1,737 massive concrete segments to reinforce the structure.
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