The collapse of the Tacoma Narrows Bridge is one of the most dramatic – and best documented – engineering failures in history. The moment the deck was built, the bridge could be seen oscillating during high winds. Construction workers nicknamed the bridge “Galloping Gertie” for its persistent, rolling motion in windy weather. Transit authorities deemed the bridge structurally sound, and it opened to the public on July 1, 1940.

As tourists flocked to see “Galloping Gertie,” structural engineers attempted to arrest the rolling motion of the bridge. Several additional cables were installed, both to cement blocks offshore and to connect the main cables to the bridge deck at the midpoint. Builders also equipped the bridge with hydraulic buffers to damp motion. When each of these reinforcements failed, the Washington Toll Bridge Authority hired Professor Frederick Burt Farquharson to perform wind tunnel tests and recommend a solution to the bridge’s undulation in high winds. The bridge collapsed before his suggestions could be implemented, but video footage shows Professor Farquharson standing on the bridge moments before its collapse, studying the effects of the gale on the structure.

The collapse of the Tacoma Narrows Bridge, which occurred on November 7, 1940, remains one of the most infamous structural engineering disasters of the twentieth century. The collapse was caught on film.

Later research attributed the bridge’s collapse to a number of factors, including:

• Insufficient deck weight
• Insufficient deck depth
• An unprecedented deck width to center-span ratio (1 to 72)
• Cables anchored too far from the side spans
• Use of plate girders instead of open lattice trusses, which forced wind above and below the bridge

The bridge successfully rebuilt using a new, reinforced design by the University of Washington Engineering Experimentation Station, which utilized the original tower foundations and anchorage. The Tacoma Narrows Bridge collapse led to innovations in the design and construction of suspension bridges that are still used by structural engineers today.