15. The Tacoma Narrows Bridge collapsed in 1940 after only four months in operation due to a never-before-seen physical phenomenon that caused the suspension bridge to twist violently in high winds.
The Tacoma Narrows Bridge, traversing the Puget Sound between Tacoma and the Kitsap Peninsula in the U.S. state of Washington, opened on July 1, 1940, as the third-longest suspension bridge in the world. Nicknamed the “Galloping Gertie” by workers during its construction, the bridge was known to move vertically in strong winds and despite several attempts to rectify this critical problem, none were ultimately successful. On November 7, 1940, after enduring sustained 40-mile-per-hour winds, at 11:00 am the bridge collapsed with only one fatality: a cocker spaniel named Tubby. His owner, Leonard Coatsworth, abandoned both his car and dog to crawl 500 yards along the collapsing bridge, reaching safety just in time to see both plunge into the Narrows.
The collapse of the Tacoma Narrows Bridge was due to the never-before-seen phenomenon of “torsional vibration mode”, causing the two halves of the bridge to twist in opposite directions whilst the center remained motionless. Over time, the force produced by the fluttering movements surpassed the strength of the suspender cables, snapping them one by one until the remainder were unable to support the mass of the bridge. In 1950 a new bridge was opened to replace the failed enterprise, using the original pedestals and cable anchorages but, importantly, a different design.