Engineers had built a slender, elegant suspension bridge across Puget Sound, but its narrow, shallow deck made it dangerously susceptible to wind-induced oscillation. Drivers crossing on opening day felt their cars ripple up and down as if riding ocean swells. The bridge became a tourist attraction for the sensation until November 7, 1940, when 40-mph winds tore it apart in a now-famous collapse captured on film.
Locals loved it immediately, not despite the swaying but because of it. Some drivers deliberately timed their crossings to catch the bridge undulating, watching the car ahead disappear and reappear over the crests of concrete waves. Engineers had warned about aerodynamic instability, but the design, prized for its slender beauty and lower cost, went ahead anyway.
Four months later, on November 7, 1940, sustained 42-mph winds set the deck twisting so violently that a professor's camera captured the entire collapse on film, footage still shown in engineering classrooms worldwide as the textbook case of resonance and aeroelastic flutter.
Remarkably, only one casualty resulted from the collapse: a cocker spaniel named Tubby, abandoned in a car when its owner fled on foot. The disaster fundamentally reshaped bridge engineering, forcing designers to account for wind dynamics with a rigor the original builders never imagined necessary.
Key people: Leon Moisseiff