1940 newsreel of suspension bridge ribboning in the wind and then collapsing

By Abraham Piper


Tacoma Bridge Collapse

When the Tacoma Narrows Bridge was opened in July of 1940 it was the third-longest suspension bridge in the world. Only four months later, though, the bridge proved to have been misengineered as it coiled and buckled against the relatively low pressure of 30-40 mph winds…

It is a wonderful and amazing fact that no people died in the collapse.

One life was lost, however. You can see in the footage a stalled vehicle that had to be abandoned on the bridge. Unfortunately, there was a Cocker Spaniel in it who wouldn’t leave. Two men tried to bring the dog with them, but in its panic it bit them both and the would-be rescuers had to return to solid ground to protect their own lives.

On a happier note, this footage and the bridge collapse in general are known today largely for the positive and important influence they’ve had on engineering since 1940. According to Wikipedia

The bridge collapse had lasting effects on science and engineering. In many undergraduate physics texts the event is presented as an example of elementary forced resonance with the wind providing an external periodic frequency that matched the natural structural frequency, even though the real cause of the bridge’s failure was aeroelastic flutter.

A contributing factor was its solid sides, not allowing wind to pass through the bridge’s deck. Thus its design allowed the bridge to catch the wind and sway, which ultimately took it down.┬áIts failure also boosted research in the field of bridge aerodynamics/aeroelastics, fields which have influenced the designs of all the world’s great long-span bridges built since 1940.