My comment wasn't directed at you. The first part of my comment was confirmation of what you said about it probably not helping. The second part was in reference to politicians breaking out the blamethrowers barely an hour after the collapse.

One obvious practical step straight away, no
bumper to bumper holdups over bridges for
now. Traffic lights and "no stopping" boxes
on bridge road surfaces. Only a quarter
capacity for now. Is it happening already?

Actually the bumper-to-bumper traffic looks to have helped saved lives. Since the cars were creeping or stopped when the bridge collapsed, they didn't have forward momentum to carry them off an edge if they were left on a suspended section, or into the water, if they were on one of the sections that fell first.

Of course it sucked to be the ones that happened to be straddling a joint at the time.

There is really not much reason to be surprised that this bridge failed. Two years ago an inspection gave it a rating of 50 pts out of a possible 120 pts. This was a strong indication that basic engineering maintainance was necessary. Unfortunately, rather than spend the money for this much needed maintainance, a decision was made to defer the maintainance and repair and make plans to replace the structure in 2012. The result was an eventual collapse of the bridge as its condition continued to deteriorate.

It is unfortuante that American society in general tends to see such structures as safe or unsafe, sound or unsound. The reality is that all structures slowly deteriorate over time because of exposure to the elements and basic use. Just as commercial aircraft slowly deteriorate and need maintainance after thousands of cycles of pressurization/depressurization, so bridges need maintainance after millions of repeated cycles of loading and unloading produced by the traffic they experience over their life. In the case of this bridge that maintainance was deferred.

The problem with the model of deferred maintainance is that inspection and our basic understanding of strength of materials in general is not an exact science. Inspections are based on a statistical subset of the elements that make up a structure. This statistical sampling comes with a coefficient of variation of uncertainty surrounding it. As long as the engineering safety factor built into the bridge is significantly greater than that variation, the structure is sound. The trouble begins when expected deterioration begins to occur and slowly erodes that margin of safety.

The real problem is, that we simply cannot be sure exactly when that safety factor has been eroded to the point that the structure is in danger. If we don't want loss of life and the economic consequences associated with a failure of this kind, we as a society should operate from a model of aggressive maintainance and repair rather than a deferred maintainance model. This bridge has failed and we are already hearing that no expense will be spared to rebuild it and return it to service and see that it never fails again. My question, however, concerns the thousands of bridges across the country in similar condition that are in a similar state. The inspections have been done, the deterioration has been documented, but the funds needed for maintainance and repair have not been allocated. In the end, the fault is ours... we as a society simply don't elect enough politicians who run on a platform of raising taxes and repairing our failing infrastructure. Oh yes, we elect some, but not enough and somehow the word does not get funded and in general our society is satisfied with that result.

In one of the other forums on this board, a thread raises the question as to whether the next president will cut the program to return the United States to the moon. Personally I don't think he will have any choice unless we as a society make a decision to raise taxes and fund the program. If we are not prepared to raise taxes to pay for the repair and maintainance needed on the thousands of bridges and other infrastructure elements that are in bad need of funding, where is the money going to come from to go back to the moon.

I am always amused when something of this sort occurs and we as a people are shocked and horrified. Engineers have been warning for years that too much of our infrastructure is living on borrowed time... that a major reinvestment is needed. That there have not been more failures is a tribute to the quality of the original construction. Will this failure shock people into voting the tens of millions of dollars (perhaps more) needed for the bridges that are in bad need of repair but have not failed yet??

{Emphasis mine}
"Blamethrowers!" What a lovely word, I'll have to remember it and use it.

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Microsoft is over if you want it.

The bar has been lowered for the promotion of ATM ideas; the bar for the acceptance of ATM ideas must remain high.

I'll have to credit Mystery Men for coming up with it. but it's oh so appropriate.

A distant perspective:

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*

Minnesota's worst bridges

===

Acoustic weapon? Please. This reply is more than it is worth.

===

How did so many survive?

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0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 ...

So... why is it that people would rather invent the most wild, silly faerytales than take responsibility for their own foolish behavior. This bridge was a disaster waiting to happen. The report from the last inspection was a strong indication that it was a gambol to delay basic structural repair and maintainance. That gambol was lost... perhaps next time we will be wiser.

that's just what They want you to believe..

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"blacker than the blackest black... times infinity."- Nathan Explosion
The.. Best.. Thread..Ever...

Heck yeah! I would rather go miles out of my way than on the Viaduct.

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Gillian

"Now everyone was giving her that kind of look UFOlogists get when they suddenly say, 'Hey, if you shade your eyes you can see it is just a flock of geese after all.'"

"You can't erase icing."

"I can't believe it doesn't work! I found it on the internet, man!"

I had lunch and chatted with a family member of the Chief Bridge Inspector for State of Minnesota. The family member quoted the inspector as saying that the bridge had some of the biggest cracks he had ever seen; but was also quick to add that cracks in the concrete are not the sole, or even the most accurate indicator.

My response: True, but that could just as easily mean it was even worse than the cracks indicated.

I'm still wondering about the parameters for that Minimum Tolerable category. It was minimally tolerable several years ago. After at least 4 more years of the heaviest traffic on any bridge in the state, it still fell into that same category. I wonder if anything standing but not actually starting to fall apart is "Minimally Tolerable?"

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Don of Borg - Cool, Calm, Collective.

"Within the next generation I believe that the world's leaders will discover that infant conditioning and narco-hypnosis are more efficient, as instruments of government, than clubs and prisons, and that the lust for power can be just as completely satisfied by suggesting people into loving their servitude as by flogging them and kicking them into obedience." -- Aldous Huxley

That's the problem with a classification such as "Minimally Tolerable", it is more political than scientific. There is, in fact only risk assessment and statistical probabilities. A tag of "Minimally Tolerable" basically depends on the question, "How lucky do you feel?"

You're looking down the on ramp to the Interstate 35W Mississippi River Bridge. The most traveled bridge in the state of Minnesota - capable of carrying 180,000 vehicles each day. Now at some point in the past this bridge had 6 years left in it. But i can't remember when that was. It might have been 4 years ago, or 5 years ago, or it might have been 6 years ago. The thing you've got to ask yourself is "Do I feel lucky today? Well, do you commuter?"

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Don of Borg - Cool, Calm, Collective.

"Within the next generation I believe that the world's leaders will discover that infant conditioning and narco-hypnosis are more efficient, as instruments of government, than clubs and prisons, and that the lust for power can be just as completely satisfied by suggesting people into loving their servitude as by flogging them and kicking them into obedience." -- Aldous Huxley

One cannot quantify the amount time a heavily used structure like that has left in it. As I said, one can predict, but with that prediction comes a coefficient of variance because the exact behavior of the composite materials like concrete and steal cannot be easily quantified, and because inspections of such structures is statistical in nature rather deterministic.

Speaking of MN bridges, there was an obscure one that possibly only fellow St. Cloud State (please do not laugh) attendees might know about. Just south of the campus area there are some good sized islands in the Mississippi; and there was an ancient iron truss bridge that went out to one of them. They must have been occupied (legally) at some time in the past.

Anyway, legal residence on the island ended long ago, but the bridge was never removed. The old wooden decking eventually rotted away and all that was left were the steel girders. I had heard stories about it and a professor friend of mine took me to see it. He told me tales of a small beat culture of squatters that surrounded the island.

So we follow a little dirt 2-track to the entrance of the bridge. People had thrown sheets of plywood and scraps of lumber over the girders and were driving across on that. You basically had to drive with wheels on the girders, with the loose pieces of wood giving just a small margin of error in case you meandered a bit.

Just a bit of SCSU lore about a charming little place. I'm gonna have to Google it and see what the image shows. I think it was called Beaver Island.

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Don of Borg - Cool, Calm, Collective.

"Within the next generation I believe that the world's leaders will discover that infant conditioning and narco-hypnosis are more efficient, as instruments of government, than clubs and prisons, and that the lust for power can be just as completely satisfied by suggesting people into loving their servitude as by flogging them and kicking them into obedience." -- Aldous Huxley

Found it:

http://www.mapquest.com/maps/map.adp...zipcode=#south

Love these internet goodies.

The image does not zoom in enough to clearly tell exactly what it is; but there is definitiely something there at the end of Sportsman's Island Road. I would not have expected that bridge to still be there. That's a really neat little island group. It does not show on the map, but does in the aerial image. I used to hike around some of those islands from the east bank. There is a main channel that is relatively deep and swift, but you can walk to many of the islands from the east and only encounter waist deep water.

Oh yeah, the bridge. When I saw it, it would have had to be a zero on the 120 point scale that is now becoming so well known.

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Don of Borg - Cool, Calm, Collective.

"Within the next generation I believe that the world's leaders will discover that infant conditioning and narco-hypnosis are more efficient, as instruments of government, than clubs and prisons, and that the lust for power can be just as completely satisfied by suggesting people into loving their servitude as by flogging them and kicking them into obedience." -- Aldous Huxley

Try Google Earth.


Bob Clark

tonight on the news, they said that the construction workers that had been working on it were complaining of the bridge swaying back and forth for the last couple of weeks more than they were really comfortable with, and that it was making noises.
i wonder how high up the MnDOT chain of command that info made it before the collapse?

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"blacker than the blackest black... times infinity."- Nathan Explosion
The.. Best.. Thread..Ever...

Assuming that Russian observatory did pick up something (why they would be scanning acoustic frequencies is beyond me) Would it not be just some subsonic sounds emitted by the materials of the bridge as they were failing.

When I did my first degree we covered acoustic sensors on major metal structures that were there to listen for cracks, and in recent years they have been detecting with them the snapping of cables in suspension bridges. If materials did give out a certain subsonic signature just before failure, could we not fashion sensors to listen for them and trigger some kind of warning.

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They keep saying the only construction being done was the road surface, and that it would have no effect on the structural integrity. Then I hear that they were jackhammering holes completely thru from the top of the deck. You could look down thru removed sections and see the water. That has no effect on the overall strength of the bridge? I'm asking, because I don't know.

Also, frequent users are aware that there is more bounce to that bridge than anything else it's size around here. If you are moving slow in traffic going one way, and trucks go by the other way; there is quite a bit of deck movement. Again, could be normal for that type of design, but very unnerving. There are plenty of people, including commercial operators, who swear they have avoided it for years because of how much it bounced under load.

I wonder if when the inspections information is made available if we'll see any quantifiable data such as how much bounce it had versus how much is normal, etc.

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Don of Borg - Cool, Calm, Collective.

"Within the next generation I believe that the world's leaders will discover that infant conditioning and narco-hypnosis are more efficient, as instruments of government, than clubs and prisons, and that the lust for power can be just as completely satisfied by suggesting people into loving their servitude as by flogging them and kicking them into obedience." -- Aldous Huxley

If they're only jackhammering the deck, then it wouldn't qualify as directly altering the support structure.

However, the jackhammer would certainly create vibrations. I gather that the authorities are going to investigate whether that could have worsened existing minor fatigue cracks.

The real problem is, that we simply cannot be sure exactly when that safety factor has been eroded to the point that the structure is in danger. If we don't want loss of life and the economic consequences associated with a failure of this kind, we as a society should operate from a model of aggressive maintainance and repair rather than a deferred maintainance model. This bridge has failed and we are already hearing that no expense will be spared to rebuild it and return it to service and see that it never fails again.

Deferring maintenance is a fool's economy. It'll always cost more in the end. Instead of paying millions (perhaps tens of millions) to repair this bridge, they'll have to pay hundreds of millions to replace it as well as the inevitable lawsuits.

I see this foolish economy in practice on a regular basis. I've heard of school districts who neglected to patch a small leak in a roof only to have to pay for major structural damage (and often mold mitigation) later. I've seen people who neglict basic auto maintenance who then complain that the car isn't reliable.* Better to pay for maintenance as needed and keep the vehicle in operation instead of having to replace it prematurely or pay for major repairs.

*Almost 30 years ago, my oldest brother (a very good auto mechanic) told me a story that stuck with me. He said that he got to teach a woman an "$800 lesson on what a dipstick was." She had bought a new Honda Civic and ran it for a couple years, totaling about 33,000 miles. In all that time, she'd never once checked the oil or had it changed. Even when the oil pressure idiot light came on, she kept driving. Finally, the engine seized. It had less than a cup of oil left. My brother ended up having to replace most of the engine at a cost of $800. Had she changed the oil every 3,000 miles (at a cost of about $10 back then), it would've cost her about $110. Instead, it cost her $800. That's a fool's economy. Individual people do it on a small scale. Governments do it on a massive scale. At least when individuals do it, it only ends up costing them. When governments screw up, we all end up paying.

Sadly, most DOTs in the USA have only recently learned this. Same for paying the "extra" cost of building things to last.

A while back I read about an interesting anecdote on that subject: It costs Germany much less to maintain its highways than the USA does. The standard road bed used in Germany is something on the order of 60% thicker than what's used in the USA, which makes the pavement much less susceptible to fatigue cracking.

This is true of most of the infrastructure in this country. We tend to live in a fool's dream filled with charts and equations showing that lowering taxes will through black magic and mathematical theory increase the funds available for such maintainance and repair. At this point we have one of the lowest tax tax rates among the industrial countries and funding for infrastructure is sadly lacking. What I can't believe is that inspite of this there are still calls for lower taxes... mean while roads and other infrastructure elements rot out from under us :rolls eyes:

This is true of most of the infrastructure in this country. We tend to live in a fool's dream filled with charts and equations showing that lowering taxes will through black magic and mathematical theory increase the funds available for such maintainance and repair. At this point we have one of the lowest tax tax rates among the industrial countries and funding for infrastructure is sadly lacking. What I can't believe is that inspite of this there are still calls for lower taxes... mean while roads and other infrastructure elements rot out from under us :rolls eyes:

Except that lowering tax rates has been repeatedly proven effective at increasing tax revenues because it stimulates the economy. People also tend to change their behavior when they aren't being subjected to punitive tax rates. Back in the 1980s, when they lowered the highest federal income marginal tax rates from over 50% to about 28%, people had a financial incentive to earn more than to try to shelter their income. As a result, they ended up paying more taxes than before but they were still better off. You can consult the IRS websites for proof of these assertions. Unfortunately, government choose to spend far more than the increased revenues.

There are two sides to the equation - revenues collected vs. spending. If my income decreases, so does my spending. That never happens with government. They always spend more.

As for Minnesota tax revenues in particular, a prominent local blogger examined it yesterday.

The 20-cent tax had fed fuel-tax revenue increases for many years without raising the tax rate itself. Why? More people moved to Minnesota, and more people drove more miles. Until gas prices started to rise, people had no problem buying gas for their cars. After prices became an issue, people bought more efficient vehicles and bought fewer gallons of gasoline. In other words, higher prices led to less fuel bought. What do gas-tax increase advocates think will happen when the state artificially increases prices again?

In any case, the numbers remained well over $600 million per year in revenue, or almost as much as the federal highway funds, after a 46% increase in the latter over the last six-year period. But that's not the only source for highway funds here in Minnesota. City and county governments spend their property-tax revenues on streets and highways.

Even more significantly, vehicle registration fees go to highways as well. In FY2006, that accounted for $484 million in revenue. According to the Minnesota legislature, 31% of that goes to highways, 23% to transit alternatives -- and 46% goes to the general fund. That adds roughly $150 million to the state's highway funding, which in 2006 meant around $780 million, apart from the federal funds available.

But wait -- there's more! A percentage of motor vehicle sales taxes also go to highway funds. In the last three years, that has mean an additional $500 million. Adding the 2006 portion to the other funding, we now have about $940 million in state revenues going to highways in that year. After this year, though, the percentage of MVST revenues for highway funding changes ... by going up. Instead of 30%, it will go up to 38% in 2007, 46% in 2008, and beginning in 2012, 60%.

Between state and federal tax revenues, MnDOT had around $1.6 billion dollars, some of it earmarked, for highways in FY 2006, and probably has more this year. That could have paid for at least three new bridges to replace the St Anthony Bridge, if necessary, just in 2006 alone.

I'd say the notion that we don't collect enough revenue to make our bridges safe is at least premature.

Addendum: Oh, and let's not forget that we have a $2 billion surplus over the next three years. Why not use that instead of a tax increase? We're already overcollecting as it is.

Well that's great... in the mean time, the bridges and highways in Minnesota continue to rot out from under the drivers for lack of funding. Thank the gods that there is plenty of money though, other wise there would be a problem wouldn't there...

At the risk of derailing this into a discussion on economics:

I'm pretty sure the real world is a bit too complicated to allow for the idea that we can assume a tax cut will increase revenue.

On one end, a 0% rate will result in zero revenue. At the other end of the scale, a 100% tax rate would completely destroy the above-the-table economy, pushing government revenue down to zero in the process. Clearly there must be at least one 'ideal' rate somewhere in the middle. Revenue is going to trail off on both sides of that point. So you can't say whether a cut will increase or decrease revenue unless you know what that optimal tax rate is.

Tangentially, I find it interesting that one doesn't really find folks who argue that we should shoot for some optimal rate. Just people who push for lower taxes and people who push for higher taxes. Both of those standpoints strike me as painfully unrealistic.

To further confound the issue, I'm sure that in the real world there are all sorts of variables other than the tax rate. That would suggest that the landscape is swarming with all sorts of local maxima. If that's the case, then there would never be any sort of easy answer as to whether taxes are too high or too low to produce optimal government revenue.

well, right. Because there are swarms of ways to spend tax-generated monies. Taking tax monies and burying them in a hole in Ufbuxawana ME is almost always going to hurt.

Finding an optimal rate is no easy thing to do. In the United States, the most recent federal tax cuts resulted in an increase in annual revenue. As the previous poster mentioned, however, spending went WAY up as well. The initial reaction was a short term decrease in revenue attributable to the economic impact of 9/11 and the fact that the US was already entering a recession. Recovery turned this around and federal revenues are well in excess of the 90's tech boom. So is spending.

So, do we lower them again? Are we at the optimal rate? Or do we increase taxes?

Keep in mind, those that feel we don't pay enough in taxes are free to donate extra if they'd like.

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