by Dana Lancer
Researchers at the U.S. Marine Academy’s civil engineering labs have determined that the designers of the original Tacoma Narrows Bridge were not responsible for that structure’s spectacular 1940 collapse.
“It’s those videos,” commented Dr. Ramsey Archer, head of the research team. “Millions of people have seen footage of the bridge’s gyrating plunge over and over again, ad nauseam. Very cool to watch, but it’s lousy science.”
Dr. Ramsey’s idea was to have cadets, as the Marine Academy’s students are known, build a 1/200th scale replica of the bridge and reproduce the winds that destroyed it.
“It was an excellent use of our wind tunnel and the cadets loved it,” said Ramsey.
Multiple tests failed to break the model, leading to the conclusion that the original bridge was sound.
“Oh, sure it bucked and wobbled but that just made it kind of fun—sort of like a roller coaster toll road,” commented one of the students involved in the project. “It was pretty awesome. It made me wish I had been alive to drive across the real thing.”
According to Ramsey and other members of the Academy’s engineering faculty, evidence of human error in the bridge’s design was always lacking.
“No one was able to really prove the occurrence of aeroelastic flutter. Sure it looked like there was torsional vibration and there was all that wave action in the weeks prior to its collapse, but nobody actually measured the bridge’s movement on the day it fell—until now. ” Torsional vibration refers to the violent twisting and bucking motion observed in the frequently shown images of the disaster.
Lack of evidence that winds brought the bridge down has led the research team to declare it structurally sound.
“Yes,” said Prof. Rod Buttress, one of the project’s other leaders, “they did save money by using shallower girders and less stiffening than the original design called for, but who doesn’t want to save money? I’m telling you, there was absolutely nothing wrong with that bridge.”
The research team did not offer any firm theories as to what caused the original bridge’s demise.
“Maybe terrorism,” said Capt. Hale Vessel, associate chair of the Marine Academy’s civil engineering department. “Or maybe the paint they used corroded the cables. Who the heck knows? Anyway, at least nobody died. Though it is a shame about that little dog.”
Students participating in the study received credit for a senior practicum in structural mechanics, a course colloquially known as “Hoist and Duck.”
“It was a great opportunity,” commented one of the students. “And almost as much fun as blowing things up.”