Tacoma Narrows Bridge Collapse: 1940 Footage Shows Dramatic Resonance Failure

In 1940, the Tacoma Narrows Bridge in Washington State collapsed in a spectacular fashion, just four months after it opened. The event was captured on film and has become a classic example of the dangers of resonance in engineering.

The bridge had been designed to withstand high winds, but on November 7th, a 40mph wind caused the bridge to start swaying back and forth. The motion grew more and more violent, until the bridge began twisting and buckling.

The collapse was captured on film by a local resident, Barney Elliott, who set up his camera on the shore. The footage shows the bridge swaying back and forth, with the roadway rising and falling like a wave. Finally, the center section of the bridge breaks apart and falls into the water below.

The collapse was caused by a phenomenon known as resonance, which occurs when a structure is subjected to a vibration that matches its natural frequency. In the case of the Tacoma Narrows Bridge, the wind was causing the bridge to vibrate at its natural frequency, which gradually grew more and more intense until it exceeded the strength of the structure.

The collapse of the Tacoma Narrows Bridge was a wake-up call for engineers, who realized that resonance could be a serious threat to large structures like bridges and buildings. As a result, new design techniques were developed to prevent resonance from occurring, and existing structures were retrofitted to make them more resistant to vibration.

Today, the collapse of the Tacoma Narrows Bridge is still studied by engineering students around the world as a cautionary tale about the importance of understanding the physics of vibration and resonance.