The idea behind acquiring insurance is that one party, the insurer, will guarantee payment for a future event that is unforeseeable. Meanwhile, another party, the insured or policyholder, pays the insurer a lower premium for that protection against an unknown future event. But did you know infrastructures can be insured as well?
An insurance agent sold an $800,000 policy on the Tacoma Narrows Bridge in 1940 and secretly pocketed the premium, believing the new bridge was indestructible. Four months after it opened, the bridge collapsed spectacularly, and the agent was imprisoned for fraud.
Who Designed the Tacoma Narrows Bridge?
Leon Moisseiff, the bridge’s designer, intended for it to be the most flexible bridge made. It was definitely the first of its kind. Back then, engineers were pretty confident about the design even when the ratios of length, depth, and width were beyond the standard. They believed it was a safe infrastructure. What everyone forgot to factor in was the aerodynamic forces involved. (Source: History)
The Tacoma Narrows Bridge
The Tacoma Narrows Bridge was the historical name given to the twin suspension bridge that spanned the Tacoma Narrows strait and was built in 1940. Four months later, it crashed due to aeroelastic flutter. Since then, the failure phenomenon of suspension cable bridges has become a popular topic, with several case studies discussing it.
The Tacoma Narrows Bridge in Washington was completed and opened to traffic on July 1st, 1940. It was the first bridge to use a series of plate girders to support the roadbed and the first bridge of its kind. It was a cable suspension. It was also the third-largest suspension bridge globally, with a central span of 2800 feet and two side spans of 1100 feet each.
The first Tacoma Narrows Bridge collapsed four months after it opened, on November 7, 1940, in a wind of about 42 miles per hour. The 2,800-foot main span began a series of torsional oscillations, the amplitude of which steadily increased until the convolutions ripped several suspenders loose and the span broke up. The section formed by the roadway and stiffening plate girders, rather than web trusses, did not absorb wind turbulence, according to an investigation.
At the same time, the span’s flexibility was enhanced by the narrow two-lane roadway. This combination made the bridge extremely vulnerable to aerodynamic forces, which were unknown at the time. The failure, which had no fatalities because the bridge was closed in time, sparked aerodynamic research and resulted in significant advances. In suspension bridge design, the plate girder was abandoned.
At the same time, the span’s flexibility was enhanced by the narrow two-lane roadway. This combination made the bridge extremely vulnerable to unknown aerodynamic forces. The failure, which had no fatalities because the bridge was closed in time, sparked significant advances in aerodynamic research. In suspension bridge design, the plate girder was abandoned.
(Source: Washington Department of Transportation)
What Happened to Haltlet R. French?
Hallett R. French was taken aback when he learned of Galloping Gertie’s death on November 7, 1940. The 45-year-old Seattle-based insurance agent for Merchants’ Fire Assurance Company of New York had written the State an $800,000 policy on the bridge.
The French believed the bridge had no chance of collapsing. As a result, French, being a rather inept criminal, deposited the $8,000 in premiums in his bank account without informing his firm of the transaction. On November 8, he was on vacation in Idaho when he received word that something was wrong at the Narrows. (Source: Washington Department of Transportation)