Twisting motion of the center span This photograph shows the twisting motion of the center span just prior to failure.
When the twisting motion was at the maximum, elevation of the sidewalk at the right was 28 feet higher than the sidewalk at the left.
This photograph actually caught the first failure shortly before 11:00 a.m. as the first chunck of concrete dropped out of the roadway.
A few minutes after the first piece of concrete fell, this 600 foot section broke out of the suspension span, turning upside down as it crashed in Puget Sound. The square object in mid-air (near the center of the photograph) is a 25 foot section of concrete pavement. Notice the car in the top right corner.
This photograph shows the sag in the east span after the failure. With the center span gone there was nothing to counter balance the weight of the side spans. The sag was 45 feet.
This picture was taken shortly after the failure.
The top left picture shows the center span diagonal ties and their connections. The top right picture shows the slackening of the tie due to twisting. The bottom left picture shows the frayed main cable after failure. About 500 wires are cut. The bottom right shot shows the diagonal ties after the failure.
This picture shows the buckling of the suspended floor system near the center of the side spans. The top right picture shows the suspender connections and the type of cables used for this connection.
This picture shows the size of the towers and the type of construction used. There is a slight buckling of the tower as a result of the additional strain caused after the center span collapsed. The towers were made out of structural carbon steel.

The preceding images and captions were taken from the report:
Smith, Doug,
A Case Study and Analysis of the Tacoma Narrows Bridge Failure
99.497 Engineering Project,
Department of Mechanical Engineering, Carleton University, Ottawa, Canada, March 29, 1974.
Supervised by Professor G. Kardos.

Thanks to Professor Geza Kardos, Carleton University, for permission to use this page, which can be found on the Internet at