Don -- Minneapolis road bridge collapse

After a Computer crash and the demise of civilization, it was learned
19:04:22 -0700 in rec.crafts.metalworking :


    Still not "paranoia" to be aware of that. Like I said, paranoia is the delusion they are working together. Now, being the object of a real conspiracy, that is another thing. I seem to recall a US government official committed suicide in the fifties because he thought he was going crazy, thinking that people were following him. Later it came out, that people had been following him!

    It never really was all that common, or it would not have been noted as such :-) Planning ahead was just one of those things which prudent men did. And that included paying attention to those things which could go wrong, and preparing for them. Be it flood, fire, famine or Federal Assistance Programs - as we used to say in Naval architecture "Plan Ahead, you will need one some day."
pyotr -- pyotr filipivich "Quemadmoeum gladuis neminem occidit, occidentis telum est. " Lucius Annaeus Seneca, circa 45 AD (A sword is never a killer, it is a tool in the killer's hands.)
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wrote:

Believe this: It is NOT paranoia if they are, in all reality, out to get you. And this government is out to get anyone who doesn't dance to their tune. We all used to "hear" about the CIA and the feds who did this and that. And then, with the releasing of documents, we found out that it was much worse than anyone even imagined. People who used to put out the idea that it was time to move to the mountains and bunker in were thought to have had one too many acid trips. Now, they are considered unheard prophets.
Tighten your belts, people, and stock up on ammunition. If the government don't get us, the Mexicans will. Either that or social rot.
I'm voting for social rot.
Steve
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SteveB wrote:

From all appearances, it seems that you are well ahead of the game in that aspect.
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OTOH, we lose that many killed on the roads every 3 months and even more killed in hospitals by bad care. You are more likely to be killed by cars/hospitals than by terrorists, especially if you live in FreeAmerica where terrorists avoid ;) Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/
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Gunner wrote:

Or evil forces like corrosion, fatigue, wear, settling, etc. Stuff like bridges should have some SERIOUS redundancy in them, especially with all the recent problems of major structural members cracking due to fatigue. But, a number of these major civil structures lately seem to have VERY limited redundancy.
Our local paper reported today that the local bridge with the highest structural rating was built in 1874! (St. Louis' Eads bridge.) They tested it by parking the train deck full of locomotives from river bank to river bank. Now, that's a proof load!
Jon
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wrote:

I would ask the Loizeaux Brothers (Controlled Demolition Inc.) to rate the structure. If they say it'll take multiple charges properly placed and sequenced to drop it, then it's 'safe' under that light.
But that Minneapolis bridge? I'd need the drawings and someone with demolitions experience, but I'll betcha one simple little brick of plastique in the right place (or two simple linear shaped charges and a few rubber bands) and you get the same effect.

And I'll bet they did the calculations that the bridge would sag six inches with that load - and it went down two.
Some engineers took pride in making their work bulletproof, easy to maintain, and yet not too expensive. Now it's cheap, period.
--<< Bruce >>--
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Ignoramus2331 wrote:

There's no future to taking the discussion in that direction. Any competent engineer or chemist knows a dozen ways to create mayhem on a vast scale.
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Don, That was precisely my theory, that the long line of cars, all stopping and starting, waiting to get into some lot, Stop, start. Once they started a motion on the bridge, they would have unconciencly reinforced it. Fell a slight motion, and hit the gas or brakes. The long line of cars all starting and stopping, the acceleration/ braking wavefront would travel the length of the bridege, over and over.
I wonder how many bridges get a "wavefront" on them due to a long line of cars, in stop and sop traffic?
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wrote:

Bridges aside, traffic above some level of density does exhibit some fluid flow characteristics. That was shown in studies during the 60's and 70's. You can sometimes see downstream artifacts of an event (like an accident) an hour and many miles "downstream", like clusters or concentrations of traffic between rarefactions.
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Don Foreman wrote:

Yes, and you can "relieve" that artifact by simply allowing space in front of you and smothing out the impulse - ie: drive a slow steady speed that doesn't force you to stop behind the guy in front of you.
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On Fri, 03 Aug 2007 19:50:17 GMT, cavelamb himself

One car and thoughtful driver is merely a particle in the flow, can't affect things much short of crashing or catching fire.
I agree that trying to maintain a steady rate at or slightly below avg flow speed, with variable headspace as traffic will permit, is safer and less stressful both on driver and vehicle.
When there is significant truck traffic, I try to join the trucks and travel at their speed. They're pros, keep rollin' steadily down the road, and they're big enough that hotdogs tend not to try to bluff them.
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On Thu, 02 Aug 2007 17:58:23 -0700, Half-Nutz

I've been on the Mackinaw Bridge during the Labor Day walk and experienced it "bucking". People were actually losing their footing and falling down because the bridge was swaying. I guessed maybe 6-8 inches side-to-side at the time. This was out in the middle area. The expansion joints were making a nice bang-bang-bang... all the time it was swaying. The two times I remember this were on dead calm mornings. No wind to speak of, even out in the middle of the bridge.
When the walk first starts out there will be solid people across two road lanes (the north bound or east side) for the entire length of the bridge. The other side is reduce to a single lane of bumper-to-bumper traffic in both directions.
A bit unnerving, but it hasn't fallen down yet :)
--
Leon Fisk
Grand Rapids MI/Zone 5b
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Leon Fisk wrote:

That reminds me that I have been told in the past of orders applying to UK soldiers that they break stride when crossing bridges to present problems with resonance in the structure which might result in bringing a bridge down.
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My sources say that the stop and go was before the bridge, once you hit the bridge it started to speed up to moderate speeds. And only 4 of the 8 lanes were open, the other 4 were closed for deck repair. If the lanes had truly stopped, you would have had many more cars involved. ie 4 lanes x 1200 feet of bridge, divided by 30 feet is 160 cars.
Don Foreman wrote:

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