Galloping Gertie - The Tacoma Narrows Bridge Collapse

You may hear the name, "Galloping Gertie" in the area.  Here is the history behind it. 

The Tacoma Narrows Bridge was a suspension bridge located in the state of Washington, United States, which spanned the Tacoma Narrows strait of Puget Sound. The bridge was designed by Leon Moisseiff, who was a prominent engineer at the time and was known for his work on other famous bridges such as the George Washington Bridge in New York. The construction of the Tacoma Narrows Bridge began in 1938, and it opened to traffic on July 1, 1940.

Unfortunately, the bridge was destined for disaster. Just four months after its opening, on November 7, 1940, a strong wind blew through the strait, and the bridge began to sway and twist in a dramatic and unprecedented way. The oscillations grew stronger and stronger, and after about an hour, the bridge collapsed into the water below.

The collapse of the Tacoma Narrows Bridge was a shocking event that captured the attention of the world. Fortunately, there were no fatalities, as the bridge was closed to traffic when the collapse occurred. However, the loss of the bridge was a significant blow to the local community, as it was an important transportation link between Tacoma and the Kitsap Peninsula.

So why was the bridge called "Galloping Gertie"? The nickname was given to the bridge because of the way it moved during the windstorm that led to its collapse. The twisting and swaying motion of the bridge was reminiscent of a horse galloping, and the name "Gertie" was a common name for horses at the time.

But what caused the Tacoma Narrows Bridge to collapse? There are a few different factors that contributed to the disaster. One of the main factors was the design of the bridge. Moisseiff had designed the bridge with a relatively narrow deck and a low profile, which made it more susceptible to wind-induced oscillations. Additionally, the bridge had a relatively low stiffness, which meant that it was more flexible and prone to movement.

Another factor that contributed to the collapse was the wind conditions on the day of the disaster. The wind was blowing at a relatively constant speed of around 42 miles per hour, but it was gusting in a way that created a phenomenon known as "aeroelastic flutter." Essentially, the wind was causing the bridge to vibrate in a self-excited manner, which led to the dramatic oscillations that ultimately caused the collapse.

In the aftermath of the Tacoma Narrows Bridge collapse, engineers learned valuable lessons about bridge design and wind-resistant construction. Today, suspension bridges are designed with a greater focus on stiffness and wind resistance, and they are subject to more rigorous testing and analysis before they are opened to traffic. The legacy of Galloping Gertie lives on as a cautionary tale about the importance of careful design and engineering in the construction of critical infrastructure.