The Bridge Collapse That Changed Engineering Forever

The film of the Tacoma Narrows Bridge twisting itself apart on 7 November 1940 is one of the most famous ever shot, and most copies play it about 50% too fast: it was filmed at 16 frames per second and copied to video as if it were 24. At its true speed, the deck rolled slowly, once every 5 seconds, in a steady 42 mph wind, and that is a problem for the textbook story that resonance destroyed it. This video follows the bridge from its slender design to its last morning, checks the resonance story against the numbers, shows the real mechanism (flutter: a rhythm the bridge made for itself and fed from a steady wind), and finds that engineers had watched wind wreck suspension bridges a century earlier. Chapters 0:00 The famous film runs fast 0:50 The thinnest bridge 2:45 Galloping Gertie 4:22 7 November 1940 6:53 Why the film runs fast 8:51 Looking for the rhythm 10:50 The bridge's own rhythm: flutter 13:24 A deck shaped for trouble 14:34 A lesson already learned 16:26 What changed 17:46 2020: it still happens 18:43 True speed.