Bridges have long been considered testaments to mankind's ability to overcome the most challanging geographic obstacles with engineering prowess, but a recent incident involving Europe's longest span proves yet again that nature is a force to be reckoned with. Apparently, strong winds caused the 4-mile-long bridge, which spans the Volga River in Russia, to wobble and bounce quite crazily, though it did manage to stay intact--which is more than can be said about some other bridges that tried to outwit the laws of nature.
According to a report on the incident in The Moscow Times, experts believe that the gale-force winds blowing that day are to blame for the bouncing bridge. Even Russia's Deputy Transportation Minister, Oleg Belozyorov, stopped by the bridge the next day to have it inspected, finding it to be "in perfect shape"--good news considering the bridge opened just eight months ago.
Some had originally suspected an earthquake was to blame for all the shaking, while others thought it might have been the particularly strong river current passing beneath the structure, but Belozyoroy chalks it up to the wind:
Experts agree that it is the dynamics of the air. When wind gusts hit a certain resonance zone, they cause these kinds of consequences.
The incident in Russia is reminiscent of another infamous bouncing bridge, which too was caught on camera, and has helped engineers better understand the properties of elementary forced resonance. In 1940, the Tacoma Narrows Bridge (since nicknamed "Galloping Gertie,") collapsed after enduring 40-mile-per-hour winds. Known as aeroelastic flutter, the phenomena occurred as vibrations caused by the force of the wind acted on the bridge's natural vibration, causing self-exciting oscillations, which eventually exceeded structural capacity of the bridge.
The chief engineer from Transmost, the construction company that built the span in Russia, was aware of the impact wind can have on bridges, but considered the shaking seen last week unlikely, telling The Moscow Times "specialists believe this is a unique case."
But it just goes to show that when it comes to bridges, the "troubled waters" part should actually be the least of your concerns.