Posted on 08/05/2007 3:16:09 AM PDT by nancyvideo
As of 2005, 155,144 of the nations 592,473 bridges (26.2%) were rated structurally deficient or functionally obsolete - see how bridges in your state are ranked.
(Excerpt) Read more at msnbc.msn.com ...
Gee thanks! I ran to check the list to check on “our” bridge! Now I’m even more jittery crossing that monster.
I’ve tried to walk out on to it and just can’t do it! It scares the cr@p out of me! LOL!
I had the same problem on the Golden Gate bridge a couple weekends ago! I already had acraphobia (fear of heights) but now I’ve learned there’s another stupid phobia about crossing bridges called what sounds like bfearaphobia. I don’t know how it’s spelled as I only heard it said on the radio.
You can't see it in the picture but the catwalk is in the middle below the two spans. You can see one of the pylons, just follow the green girders on the left side.
The good thing is we never got busted by the police. The more barriers they put up, the easier it was to access. I wonder if you can still get to the catwalk
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Deficient 'Burgh Bridges
One of them in Ohio is adjacent to my property, and will result in the county buying four acres of my land....eventually.
Some of those old link bridges would go down if a single link pin rusted through. Keep the paint fresh!
bump...for publicity
The question should be "what did they use for di-icing"? Otherwise, we need to replace the Golden Gate, ect. This whole thing is a tax scam.
Here in Pennsylvania, I have come to think of it as an adventure! Life with Fast Eddie Rendell.......
Here is what I am trying to say. We have learned a lot about building bridges over the years. Both with computer modeling and experience we understand now better how systems work. I guess obsolete is not the word so much as, not build with the redundancies modern bridges are built with. We also have a better technology.
For example, bridges in earthquake zones now have their rebar bent in a “cork screw” fashion (forgive me if I get this wrong because I am remembering a Science channel TV shows from years ago. It was one of the things we learned from the big earthquake out in California during the 1990s.
It isn’t that the engineering then was bad, it just that we have 40 years more experience and a whole host of tools that they did not have.
The point here is we, in Minnesota, could of upgraded that bridge any time since 1990 but choose instead to spend our “infrastructure” dollars on new projects and gimmicks. The problem here is not that the Government doesn't have enough money, but that it miss spends too much of the money it does have.
I see your point, however it is 40 years in a 2000 year old art.
We build silly bridges that load concrete in flexure (big horizontal beam, with the top section loaded in tension) Concrete is terrible in tension, it likes compression. So, we add steel tension cables to preload the span in compression. This works and keeps the entire cross section in compression. All is good until the steel fails (rust). The only reason we do this is architects hate arches. ...according to a CE friend of mine that builds bridges.
About the only thing we’ve added since the 60s is cost and some prefab capability.
You are saying steel is steel and we don’t know how to protect it better now then we did in the 1960s? That computer modeling doesn’t add anything to our understanding of how and why all the bridges that have failed since 1967 failed?
As someone who has been on and under this bridge that failed a bunch of times, I got to say, it sure looked like a poor design to me. Long spindly steel legs supporting a whole lot of concret WAY way way up in the air. However, not being an engineer I just always assumed they knew way more then me about their job.
So basically, what you are saying is it is bad design. That we could do a much better job?
Another question? How come my 1st car in the 1980s rusted so much and my current one doesn’t yet I have/had both the same amount of time? I assumed that meant we were better at protecting them now.
We haven’t learned enough to make enough of a difference to warrent changing out all of these bridges. If properly maintained they should last indefinately.
Advances in FEA and CAD are great if you want to reduce weight (FEA) or build to tighter tolerances. This is importantin autos and airplanes...Bridges are best left overbuilt and under engineerd. It’s cheaper and more durable that way.
As far as corrosion protection, sacrificial zinc is hard to beat. It would be interesting to see what is being used now. Probably nothing new.
If money as spent on maintenance instead of light rail (reflecting your frustration) then all of this infrustruction should last hundreds of years.
Thanks for the information. Most interesting. We have been slighting the things we should do here in MN
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