Brief history of: The Tacoma Narrows Bridge Collapse (1940)

Summary

The video recounts the dramatic story of the Tacoma Narrows Bridge, which opened in July 1940 as the world's third-largest suspension bridge, only to collapse three months later due to design flaws and wind-induced oscillations. Engineers attempted several fixes, but the flexible, narrow roadway acted like an aerofoil, leading to catastrophic failure. Despite the disaster, lessons learned from the bridge's collapse influenced future suspension bridge designs. The narrative also highlights the human side of the tragedy, including engineers’ struggles, the lone canine casualty, and the eventual construction of a safer replacement bridge in 1950. The video emphasizes engineering, perseverance, and historical impact.

Takeaways

• 😀 The Tacoma Narrows Bridge, also known as 'Galloping Gertie,' was opened to the public on July 1, 1940, as the third-largest suspension bridge in the world.
• 😀 The bridge collapsed just three months later, caused by a combination of a design flaw and strong winds, making it one of the most famous structural failures in history.
• 😀 The initial idea for a bridge connecting Tacoma and the Kitsap Peninsula dates back to 1889, but serious plans didn't emerge until 1923, when funding and support became viable.
• 😀 A cheaper, sleeker bridge design by engineer Leon Moisseff was chosen over a more expensive and sturdy design, reducing costs but leading to fatal flaws.
• 😀 The bridge's narrow, shallow roadway and the use of smaller girders led to excessive flexibility, which caused it to sway violently in the wind, earning it the nickname 'Galloping Gertie.'
• 😀 Despite the initial concerns about the bridge's instability, the bridge was approved, and construction began in 1938, costing $6.4 million.
• 😀 Even before its opening, the bridge was notorious for its bouncy and unstable behavior, and several attempts were made to fix its oscillation issues, but none were successful.
• 😀 On November 7, 1940, winds reached 42 mph, causing the bridge to sway uncontrollably and ultimately collapse, leading to the destruction of a large portion of the structure.
• 😀 A journalist and his dog were involved in the collapse, with the dog, Tubby, tragically disappearing when the bridge fell into the Puget Sound.
• 😀 The collapse led to a thorough investigation which revealed the primary causes: the bridge’s flexibility, poor aerodynamic design, and insufficient wind tunnel testing during planning.
• 😀 The collapse of the Tacoma Narrows Bridge became a major lesson in engineering, influencing future suspension bridge designs and construction practices.

Q & A

Who suggested the video topic to the creator?

The video topic was suggested by Tim, one of the creator's patrons.

When did the Tacoma Narrows Bridge officially open to the public?

The bridge opened on July 1, 1940.

What nickname was given to the Tacoma Narrows Bridge, and why?

It was nicknamed 'Galloping Gertie' due to its noticeable swaying and bouncing even in mild winds.

What was the main design difference between Clark Eldridge's and Leon Moisseiff's bridge proposals?

Eldridge proposed deep 7.6-meter trusses for stability, while Moisseiff suggested smaller 2.4-meter trusses to reduce cost and create a sleeker design.

What factors caused the Tacoma Narrows Bridge to collapse?

The collapse was caused by excessive flexibility due to small support girders, the roadway acting like an aerofoil producing lift and drag, and a lack of understanding of aerodynamic effects on bridges.

Who attempted to provide solutions to the bridge's instability before its collapse?

Professor Frederick B. Farquharson proposed solutions such as cutting holes in the roadway girders and fitting fairings to improve airflow, but his fixes were not implemented in time.

How long after opening did the bridge collapse?

The bridge collapsed approximately four months after opening, on November 7, 1940.

What was the financial cost of constructing the bridge, and how was it funded?

The construction cost was $6.4 million, funded by $6 million from the Public Works Administration and the remaining $8 million planned to be collected through tolls.

Were there any human casualties during the collapse?

No humans were killed, though a dog named Tubby was lost when a car it was in fell into the water.

What long-term impact did the collapse have on bridge engineering?

The collapse highlighted the importance of aerodynamic testing, wind-tunnel experiments, and stronger structural support, influencing the design of all future suspension bridges.

How did the original designers respond after the collapse?

Clark Eldridge criticized the cost-cutting measures that led to using smaller girders, while Moisseiff's career was heavily affected, and Frederick Farquharson contributed to the design of the replacement bridge in 1950.

What role did the Public Works Administration (PWA) play in the bridge project?

The PWA approved partial funding for the bridge, overlooked warnings about design flaws, and initially ignored engineer David Glenn’s rejection report, which cited fatal design issues.