Galloping Gertie: The Tacoma Narrows Bridge Collapse

Connecting Tacoma with the quaint seaside village of Gig Harbor, the first Tacoma Narrows Bridge was built from September 1938 until its grand opening on July 1, 1940.

How Long was Galloping Gertie?

Galloping Gertie was 5,400 feet long. Throughout its brief and cursed lifespan, it stood as the world’s third-longest suspension bridge by with the main span, dwarfed only by the Golden Gate in San Francisco and the George Washington Bridge in New York City.

From the moment the deck was completed, the main span began to move vertically in windy conditions, prompting construction workers to nickname the bridge Galloping Gertie.

Why Did Galloping Gertie Collapse?

Despite several damping measures added by project engineers, the bridge’s main span finally gave way in 40-mile-an-hour winds on the morning of November 7, 1940, as the deck oscillated in an alternating twisting motion that gradually increased in amplitude until the deck simply tore itself apart.

The bridge’s untimely demise has had a lasting impact on science and engineering, and while many physics books wrongly categorized the event as elementary forced resonance, the true cause was aeroelastic flutter that was self-exciting and unbounded for any constant and sustained winds above 35 mph.

Ultimately the disastrous bridge collapse boosted research into bridge aerodynamics and aeroelasticity, which profoundly influenced the designs of all future long-span bridges built around the world.

After the disaster, the still-standing towers and cables were dismantled and sold as scrap metal, while efforts to replace the bridge were delayed by the American entry into World War Two.

In 1950, a new Tacoma Narrows Bridge was opened on the same location, utilizing the original bridge’s tower pedestals and cable anchorages. The portion of the bridge that fell into the water continues to serve as an artificial reef.