Monday, June 11, 2012

The Bridge That Twisted in the Wind

The original Tacoma Narrows Bridge was one that will live in infamy for creating one of the most amazing spectacles ever captured on film: a bridge that literally twisted in the wind and ultimately collapsed on live TV.

Built in 1940, the original Tacoma Narrows Bridge (not to be confused with the twin suspension bridges now standing) was constructed to span the Tacoma Narrows Straight, which lies between the city of Tacoma, Washington and the Kitsap Pennisula. The idea for a bridge here had been tossed around since the late 1800s before the state legislature of Washington created the Washington State Toll Bridge Authority. The Toll Bridge Authority studied the requests to build a bridge in this area; they finally agreed to build in the late 1930s.

Construction began on the bridge in 1938. Almost at once, the construction crew noticed how as the bridge grew, it began to move more and more with the wind that blew through the Narrows. Once the deck was completed, it began to move up and down, vertically, with the sometimes 40-mph winds. The local papers nicknamed the bridge as Galloping Gertie.

The Tacoma Narrows Bridge was the third largest suspension bridge in the world when it opened on July 1, 1940, beaten only by the Golden Gate Bridge in San Francisco and the George Washington Bridge in Manhattan. Even after opening, work was done to try and fix the vertical movement of the bridge.

What the builders didn't know at the time was that aeroelastic flutter was what was doing the most damage. Aeroelastic flutter is the vibrations created from one object contacting another, such as wind on stone, with the effect being the forces within the struck object couple up with its own natural vibration or movement, creating even more rapid movement.

For the next few months, the bridge began to bounce up and down, more and more often, sometimes even twisting on itself like a pretzel. The cables held, but crossing the bridge became more and more difficult and dangerous. The bridge began to move in a way that was transverse, that is, when one side of the bridge went up, the other side went down.

Then came the fateful day: November 7, 1940. At 11 am, the bridge finally collapsed. Leonard Coatsworth, the editor of the Tacoma News Tribune, was the last man crossing the bridge. He had to abandon his car and his dog.

Here is his account of what happened, from the Washington State Department of Transportation:

"I drove on the bridge and started across. In the car with me was my daughter's cocker spaniel, Tubby. The car was loaded with equipment from my beach home at Arletta. 

Just as I drove past the towers, the bridge began to sway violently from side to side. Before I realized it, the tilt became so violent that I lost control of the car. . . . I jammed on the brakes and got out, only to be thrown onto my face against the curb.

Around me I could hear concrete cracking. I started back to the car to get the dog, but was thrown before I could reach it. The car itself began to slide from side to side on the roadway. I decided the bridge was breaking up and my only hope was to get back to shore.

On hands and knees most of the time, I crawled 500 yards or more to the towers . . . . My breath was coming in gasps; my knees were raw and bleeding, my hands bruised and swollen from gripping the concrete curb . . . . Toward the last, I risked rising to my feet and running a few yards at a time . . . . Safely back at the toll plaza, I saw the bridge in its final collapse and saw my car plunge into the Narrows."

The collapse of the bridge took mere moments, but the images it created have lasted nearly a century. Here is footage of the bridge and its collapse. Coatsworth's car can even be seen in the clip. (Click here if you can't view the video on your device.)


  1. Aeroelastic flutter? I never knew. I heard about this disaster but not the full science behind it. Cool!

  2. Just think: Had there simply been holes for the wind to pass through, it would still be standing today! Wild, but 100 percent true!