A scary bridge

[JerryNumbers]

http://www.youtube.com/watch?v=IqK2r5bPFTM&feature=relatedTacoma Narrows Newsreel with audio

Edited December 13, 2010 by Jerry80871852

[Invicta]

http://www.youtube.com/watch?v=IqK2r5bPFTM&feature=relatedTacoma Narrows Newsreel with audio

I saw this on TV a few years ago, but heard about it in thye 1950s when I was a school. it seems it was to do with natural resonance or harmonics. We had a similar thing about 10 years ago with the millenium footbridge accross the River Thames. It was designed so that 1,000 or more people could walk accross it safely aat the same time. But there was a natural resonance that made the bridge move. This made the walkers to all walk in step with the natural sway of the bridge and with them all walking in step the sway got more pronounced and the bridge had to be closed. Engineers had to add dampers to the brigde, a bit like on car suspension only on a much larger scale, then the bridge could be reopened.

http://en.wikipedia.org/wiki/Millennium_Bridge_%28London%29#Resonance

[Invicta]

The longest bridge spans.

http://en.wikipedia.org/wiki/List_of_longest_suspension_bridge_spans

I wouldn't get my wife accross any of those bridges. If we cross the Dartford Bridge, I have to take one of the centre lanes so she cannot see too much of the sides.

http://en.wikipedia.org/wiki/Dartford_Crossing

[HappyChristian]

*shudder* That's the exact reason I don't like going across the Tacoma Narrows bridge today! It is built better now, of course. And it is actually two bridges (now) - one for each direction. But to get to my folks' house, I either have to ride a tiny airplane from SeaTac, or go with my brother on the ferry or across the bridge. The bridge is cheaper. And, at least he drives on the inside lane so I don't have to look down into the water.....

[amblivion]

YIKES!! I am glad I didn't see this before I went to Royal Gorge and walked across the suspension bridge there. I would have never crossed it. I froze and I wasn't even 20 ft on the bridge.

[JerryNumbers]

Several years ago when hauling bulk cement we had a road jOB where we had to drive across an old wooden bridge that was about 4 to 45 foot long, and it was about 20 to 30 above the creek. As I crossed it loaded I tried to set as light inn the seat as possible.

We used to back haul lime from a lime pit at Batesville, AR to a paper mill close to Texarkana. The pit was about 3 or 4 miles off the main highway and had an old one lane bridge made from wood that was prOBably at least 250 to 350 feet long, and I suppose it was as high as it was long. The 1st time was scary, yet all the other times I crossed it was scary too.

Once had to ride an old ferry across a river while driving a 18 wheeler, the front truck wheels were nearly hanging off on the front, the back wheels were hanging off the back, that was a bit scary, yet I believe I would take it over a Tacoma Narrows bridge and a few other bridges I've seen.

[Invicta]

The very long one in Japan had to be redesigned whilst it was being built as an earthquake at the time, made the pylons over a metre further apart than they were when it was started.