Bucyrus wrote: Mailman wrote: Bucyrus wrote: There is a lot of controversy over the issue of Minnesota transportation dollars going to non-road uses. It is pretty obvious that most of the political class in Minnesota are New Urbanists, and as such, they hate private automobiles and highways, and love light rail and bicycles. What seems to work for them is to let highway construction and maintenance fall behind so there is always a public clamor to fix it, and in exchange for promises they make to fix it, they get the tax funds to divert to their favorite darlings. So broken highways and traffic jams are their golden goose. They feed the goose deferred highway maintenance and the goose lays golden eggs for light rail and bicycle trails. Apparently, in the case of the bridge collapse, they got a little careless about what they fed the goose. Broken highways and traffic jams are the perfect goose diet, but a bridge collapse should not have been on the menu because they guaranteed the bridge would not collapse. I hear what you're saying, but if there's anything to learn about this collapse, it's the fact that we shouldn't jump to conclusions about lack of maintenance $, etc. being the cause. If the contractor overloading the bridge turns out to be the "final" cause of the collapse, lack of maintenance $, etc. had nothing to do with the bridge failure.I absolutely agree, but just to be clear, I am not jumping to a conclusion that a lack maintenance funding had anything to do with the cause. In fact I insist that such a cause would be impossible. Stopping the required maintenance for any reason while leaving the bridge open for public use would be criminal negligence. So a lack of funding cannot possibly enter into the equation. My previous mention of funds being diverted was not to suggest that diverting funds shortchanged bridge maintenance. My point was that deferring road and bridge maintenance is a political tool to raise funds that can be used elsewhere to expand the power and empire of state government. This point is perfectly validated by the politicians who immediately blamed the taxpayers for the collapse, saying that they had not paid enough to keep the bridge standing. It is what they always say when we complain about inadequate highway construction and maintenance. If I sound like I am jumping to a conclusion, that conclusion could best be summed up as negligence on the part of the bridge authorities. And that negligence could have taken several possible forms. It could have been a failure to properly inspect the bridge, or a failure to properly repair damage. It also could have been a design flaw or an improper execution of the design in the original construction. Or it could have been improper oversight of the contractor doing the work at the time of the collapse. It may have been a combination of all of the above. But I won't jump to that conclusion because you are correct that there is one other possible cause that would completely exonerate the bridge authorities. That would be the possibility that the contractor doing the work at the time of the collapse violated the terms of his contract and exceeded a maximum allowable weight.
Mailman wrote: Bucyrus wrote: There is a lot of controversy over the issue of Minnesota transportation dollars going to non-road uses. It is pretty obvious that most of the political class in Minnesota are New Urbanists, and as such, they hate private automobiles and highways, and love light rail and bicycles. What seems to work for them is to let highway construction and maintenance fall behind so there is always a public clamor to fix it, and in exchange for promises they make to fix it, they get the tax funds to divert to their favorite darlings. So broken highways and traffic jams are their golden goose. They feed the goose deferred highway maintenance and the goose lays golden eggs for light rail and bicycle trails. Apparently, in the case of the bridge collapse, they got a little careless about what they fed the goose. Broken highways and traffic jams are the perfect goose diet, but a bridge collapse should not have been on the menu because they guaranteed the bridge would not collapse. I hear what you're saying, but if there's anything to learn about this collapse, it's the fact that we shouldn't jump to conclusions about lack of maintenance $, etc. being the cause. If the contractor overloading the bridge turns out to be the "final" cause of the collapse, lack of maintenance $, etc. had nothing to do with the bridge failure.
Bucyrus wrote: There is a lot of controversy over the issue of Minnesota transportation dollars going to non-road uses. It is pretty obvious that most of the political class in Minnesota are New Urbanists, and as such, they hate private automobiles and highways, and love light rail and bicycles. What seems to work for them is to let highway construction and maintenance fall behind so there is always a public clamor to fix it, and in exchange for promises they make to fix it, they get the tax funds to divert to their favorite darlings. So broken highways and traffic jams are their golden goose. They feed the goose deferred highway maintenance and the goose lays golden eggs for light rail and bicycle trails. Apparently, in the case of the bridge collapse, they got a little careless about what they fed the goose. Broken highways and traffic jams are the perfect goose diet, but a bridge collapse should not have been on the menu because they guaranteed the bridge would not collapse.
There is a lot of controversy over the issue of Minnesota transportation dollars going to non-road uses. It is pretty obvious that most of the political class in Minnesota are New Urbanists, and as such, they hate private automobiles and highways, and love light rail and bicycles. What seems to work for them is to let highway construction and maintenance fall behind so there is always a public clamor to fix it, and in exchange for promises they make to fix it, they get the tax funds to divert to their favorite darlings.
So broken highways and traffic jams are their golden goose. They feed the goose deferred highway maintenance and the goose lays golden eggs for light rail and bicycle trails. Apparently, in the case of the bridge collapse, they got a little careless about what they fed the goose. Broken highways and traffic jams are the perfect goose diet, but a bridge collapse should not have been on the menu because they guaranteed the bridge would not collapse.
I hear what you're saying, but if there's anything to learn about this collapse, it's the fact that we shouldn't jump to conclusions about lack of maintenance $, etc. being the cause.
If the contractor overloading the bridge turns out to be the "final" cause of the collapse, lack of maintenance $, etc. had nothing to do with the bridge failure.
I absolutely agree, but just to be clear, I am not jumping to a conclusion that a lack maintenance funding had anything to do with the cause. In fact I insist that such a cause would be impossible. Stopping the required maintenance for any reason while leaving the bridge open for public use would be criminal negligence. So a lack of funding cannot possibly enter into the equation.
My previous mention of funds being diverted was not to suggest that diverting funds shortchanged bridge maintenance. My point was that deferring road and bridge maintenance is a political tool to raise funds that can be used elsewhere to expand the power and empire of state government. This point is perfectly validated by the politicians who immediately blamed the taxpayers for the collapse, saying that they had not paid enough to keep the bridge standing. It is what they always say when we complain about inadequate highway construction and maintenance.
If I sound like I am jumping to a conclusion, that conclusion could best be summed up as negligence on the part of the bridge authorities. And that negligence could have taken several possible forms. It could have been a failure to properly inspect the bridge, or a failure to properly repair damage. It also could have been a design flaw or an improper execution of the design in the original construction. Or it could have been improper oversight of the contractor doing the work at the time of the collapse. It may have been a combination of all of the above.
But I won't jump to that conclusion because you are correct that there is one other possible cause that would completely exonerate the bridge authorities. That would be the possibility that the contractor doing the work at the time of the collapse violated the terms of his contract and exceeded a maximum allowable weight.
Good points.
Bucyrus wrote: Mailman wrote: Hmm......last I heard (few days ago in various media) here in MN, was that the contractor doing construction on the bridge was being looked at, for overloading the bridge with equipment, materials, etc.........hmmmm........At the time of the collapse, there was 288 tons of equipment and supplies that was placed on the bridge by the contractor who was working on the bridge. I wonder what their contract stipulated in regard to the weight of equipment and materials that was permitted to be placed on the bridge during this work. Perhaps the contractor exceeded the stipulation, or maybe the stipulation mistakenly allowed too much weight. Or maybe there was no stipulation.
Mailman wrote: Hmm......last I heard (few days ago in various media) here in MN, was that the contractor doing construction on the bridge was being looked at, for overloading the bridge with equipment, materials, etc.........hmmmm........
Hmm......last I heard (few days ago in various media) here in MN, was that the contractor doing construction on the bridge was being looked at, for overloading the bridge with equipment, materials, etc.........hmmmm........
At the time of the collapse, there was 288 tons of equipment and supplies that was placed on the bridge by the contractor who was working on the bridge. I wonder what their contract stipulated in regard to the weight of equipment and materials that was permitted to be placed on the bridge during this work. Perhaps the contractor exceeded the stipulation, or maybe the stipulation mistakenly allowed too much weight. Or maybe there was no stipulation.
Exactly. Haven't heard any more details; been to busy.
jfallon wrote: I overheard someone on talk radio screaming about how the MDOT was responsible because they funded the construction of a "useless" light rail system for the Minneapolis/St. Paul region, and could have used that money for upkeep of the bridges. While disagreeing with the main principle, there is some truth that maintenance and upkeep are the step-children of the transportation budget in most cases. It is tough enough to get tax funding for new roads and bridges where they are needed. Mass transit is often demonized as a waste of money, many voters will reject funding it if they don't think they would use it. But I am sure that a few more folks in Minnesota may be considering it now.
I overheard someone on talk radio screaming about how the MDOT was responsible because they funded the construction of a "useless" light rail system for the Minneapolis/St. Paul region, and could have used that money for upkeep of the bridges. While disagreeing with the main principle, there is some truth that maintenance and upkeep are the step-children of the transportation budget in most cases. It is tough enough to get tax funding for new roads and bridges where they are needed. Mass transit is often demonized as a waste of money, many voters will reject funding it if they don't think they would use it. But I am sure that a few more folks in Minnesota may be considering it now.
Not really (MN mass transit). The main "problem" in MN regarding metro roads, transit, etc. is that the Metro area is the only part of the state that it pertains too.
I.e., every year or so, the legislature comes up with a multi-million dollar transit project, be it new construction, repairs, mass transit or whatever. Of course, such projects require more taxes, etc. usually. If you're not familar with MN, outside of the metro area, it is basically a rural state. A very BIG, in area, rural state; the metro area is a small part of overall MN. In terms of mindset, lifestyle, etc.
Very few non-metro MN residents, myself included, get excited about having to pay for the metro areas transportation projects. They want it, they can pay for it in other words.
And so many times, such projects don't happen.
If everybody is thinking alike, then nobody is really thinking.
http://photobucket.com/tandarailroad/
I personally think the basic design of the bridge in the first place contributed to this unfortunate tragedy.
If you've seen the pictures of the bridge pre-collapse, note the following:
1) The spindly structure of the steel lattice framework beneath the roadbed.
2) The steel is exposed to the elements (note several spots of rusting, especially around the rivet joints).
3) The entire bridge over the Mississippi is held up by four very small concrete posts.
I'm surprised the bridge didn't collapse years earlier. I do see the replacement bridge to be more a traditional reinforced concrete arch structure, something that has lots of structural strength and weather resistance to start with.
I wonder what the rate of highway bridge failures is as compared to the rate of railroad bridge failures.
Obviously, there are many more highway structures, but I can think of three or four modern highway failures and no comparable railroad problems (burned bridges don't count).
Is the premise of a much greater failure rate for highways correct, or am I just remembering selectively?
Perhaps the Minnesota DOT would have us believe railroads don't attract pigeons and spiders as highways do!
I would not be surprised if pigeon poop caused corrosion. Even the spiders might have contributed some detriment with their digestive products. And there would be other types of birds as well, no doubt. Speaking of guano, the bridge was also probably home to a large numbers of bats. I can attest to the fact that bat urine will take solid color stain finish right off of a house. I would assume that the inspectors were not only prevented from seeing the steel because of all this icky stuff, but they also probably felt that it was unfair that they should have to be exposed to it.
It has also been suggested that a de-icing system installed a few years ago that might have caused chemical corrosion. And of course road salt has been implicated as a cause of corrosion. But even though all of this could have been part of the cause, it was the responsibility of the inspection authority to learn the factors leading to a collapse and prevent it. The one good thing about corrosion is that it gives you time to catch it.
So it all comes down to this question:
Why is the public being offered these explanations for a possible cause?
There are two possible answers:
1) Inspection authorities are demonstrating diligence in probing the cause, making an honest effort to satisfy the public's need to know with as much information as possible.
2) Inspection authorities are making a smokescreen to obscure the fact that they failed to perform their job.
If number two being the correct answer is not obvious, it can be arrived at by eliminating answer number one. These inspection authorities are always telling us that they cannot speculate about a cause. They must let their investigation run its course, and it might take a year or more. The new bridge might be up and running before we ever find out why the old one fell down. Moreover, since they are performing a formal investigation, there is no need for them to speculate. In fact, if they did speculate, it might cloud their objectivity with pre-conceived ideas, and thus flaw their investigation. So cognizant are they of the harm of speculation that they even warn the public to not speculate.
And yet, despite all of this stern admonishment against speculation, they are publicly rolling out theories about the role of pigeons, spiders, road salt, and de-icing chemicals. It ought to be pretty obvious that, in the case of this investigation, the need to shield themselves from blame is far greater than the need to learn the cause.
~~~
Like most major failures, the bridge collapse will probably be the result of a series of smaller contributing factors. Remember the plane crash in, IIRC, the Everglades that was the result of a $0.10 light bulb? The cockpit crew was so worried about the indication (or lack thereof) from the landing gear light that no one noticed the plane was losing altitude until it was too late.
As far as the pigeon poop, maybe this is a job for the Mythbusters. Plausible is my guess. BTW, didn't they once do an electochemical experiment about the effect of salsa on the steel bars in a jailhouse?
Jay
First, call me very skeptical about this. The acid formed is very weak and once it has been reduced chemically, its dried remains should shield the steel from further damage from subsequent droppings.
Second, using the word guano is incorrect unless a pigeon is a bat or seabird. Using an incorrect word tainted the accuracy of the rest of the article.
Maybe this was the cause of the bridge collapse, maybe it wasn't. We will find out when they officially say what caused it. Until the official cause is determined, what caused it will remain a question. In any case, Illinois (and I am sure other states also) is supposed to step up bridge inspections and close any bridge during construction. I don't know if that is possible becuase closing an major highway in this area would cause more traffic on already backed-up roads.
Bucyrus wrote: Krazykat112079 wrote: The cause of the bridge collapse will be revealed, but we already know the reason: lack of adequate quality inspections. The probable cause sure does point that way, unless something really fluky is found to be a cause that can be said to be an act of god. Bridges start to wear out the day they are opened. That is why there is a federal inspection program in place to guarantee that bridges do not become unsafe. It is similar in its rigid requirements to the federal locomotive boiler code enforcement. You have to learn the condition of all of the metal. It is quite popular for politicians to blame the people who resisted higher taxes. But that is a worse excuse than pigeon poop. That lame excuse is a political ploy to expand the government on the back of this tragedy. Even MNDOT ran away from the funding excuse because they know that it is a bogus, transparent stunt.It is true that a bridge will collapse if it is not maintained, and maintenance costs money. But a lack of money cannot possibly be the cause when you have agencies in place that only have the two options: 1) Guarantee the safety of the bridge.2) Close the bridge. Our so-called crumbling infrastructure is being used like a cash cow to pull in revenue that can be spent for anything else they happen to want. If they fix the roads and bridges they kill the cash cow. And then they won't have their several hundred millions of dollars that they siphon off the highway budget and spend on bike trails every year in Minnesota, for instance.
Krazykat112079 wrote: The cause of the bridge collapse will be revealed, but we already know the reason: lack of adequate quality inspections.
The cause of the bridge collapse will be revealed, but we already know the reason: lack of adequate quality inspections.
The probable cause sure does point that way, unless something really fluky is found to be a cause that can be said to be an act of god. Bridges start to wear out the day they are opened. That is why there is a federal inspection program in place to guarantee that bridges do not become unsafe. It is similar in its rigid requirements to the federal locomotive boiler code enforcement. You have to learn the condition of all of the metal.
It is quite popular for politicians to blame the people who resisted higher taxes. But that is a worse excuse than pigeon poop. That lame excuse is a political ploy to expand the government on the back of this tragedy. Even MNDOT ran away from the funding excuse because they know that it is a bogus, transparent stunt.
It is true that a bridge will collapse if it is not maintained, and maintenance costs money. But a lack of money cannot possibly be the cause when you have agencies in place that only have the two options:
1) Guarantee the safety of the bridge.
2) Close the bridge.
Our so-called crumbling infrastructure is being used like a cash cow to pull in revenue that can be spent for anything else they happen to want. If they fix the roads and bridges they kill the cash cow. And then they won't have their several hundred millions of dollars that they siphon off the highway budget and spend on bike trails every year in Minnesota, for instance.
Great points. If they need more money for the infrastructure on interstates, why not do what we do in Chicago and charge tolls, i.e. a user fee?
They also do it in downtown New York -- I think the last time I drove over the Verrazano Narrows bridge it cost me $4.50 one-way. And the Golden Gate and Oakland bridges in San Fran.
As alluded to above, it is systemic, and systems thinking is what will ultimately provide both the cause(s) and the remediation. I think the most insidious aspect of the systemic failure cannot be attributed to any one factor more than our homosapiens' penchant for taking the easy way out. That applies all the way down the line, from those in charge down to the great unwashed electorate. If I am correct, you should see a lot of squawking and threats and lawsuits and....you name it...from a whole bunch of strata. Finger pointing, head ducking, alliances suddenly where there were none, strange bedfellows very chummy...
But my point is that it really comes down to our preferences for the status quo as we understand it. If we really wanted that to change, and for us to have truly accountable leading engineers, executives, legislators, and such, we know what we have to do.
Well, you can bet that corrosion due to pigeon guano played some role, be it however small. The problem with this bridge, and with all structures, is that you have to look at all contributing factors and analyze their synergistic effect. Looking specifically at this bridge, you have 40 years of weathering, 40 years of pitting due to pigeon guano, 40 years of high frequency cyclic loading, 40 years of high amplitude (rush hour) cyclic loading, X number of repair/resurface/reconstruction loadings, etc.
The weathering, guano and cyclic loadings reduce the strength of the structure little by little. There was construction loading, coupled with the high amplitude, high frequency loading of rush hour. Put all of that on a weakened structure and you have a recipe for catastrophy.
wjstix wrote: Not sure how you get a firehose to a long span of bridge over a river!! Inspectors had to be lowered down the side of the bridge on ropes to look under. They tried in the limited time they had (time is money) to see everything they could, but they apparently couldn't completely clean every piece of the bridge just in case some of the dirt, droppings or whatever were covering an almost microscopic hairline crack or joint problem. Unfortunately, I'm sure many of the people in the general public who are now complaining that the bridge maintenance and inspection crews were lax were a year ago happily voting for politicians who pledged to not raise taxes even to help boost the crumbling national infrastructure.
Not sure how you get a firehose to a long span of bridge over a river!! Inspectors had to be lowered down the side of the bridge on ropes to look under. They tried in the limited time they had (time is money) to see everything they could, but they apparently couldn't completely clean every piece of the bridge just in case some of the dirt, droppings or whatever were covering an almost microscopic hairline crack or joint problem.
Unfortunately, I'm sure many of the people in the general public who are now complaining that the bridge maintenance and inspection crews were lax were a year ago happily voting for politicians who pledged to not raise taxes even to help boost the crumbling national infrastructure.
There's no shortage of companies with equipment and expertise to clean Bridges and other steel structures. Hydroblasting equipment (basically a super powerfull industrial sized power washer) is used to clean guano, ect. There was an episode of "Dirty Jobs" on the discovery channel where host Mike Rowe demonstrated how it's done. Many of these firms have truck mounted multi jointed telescoping work platforms which can get men and equipment under and into a bridge's structure.
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
tomikawaTT wrote:Typical reaction to this sort of thing - Ignore it, and maybe it'll go away.Give it 40 years of not going away and the result could easily be serious degradation of the structure.I once encountered a situation where a relief tube in the aft compartment of a KB50 had leaked undetected for an extended period of time. The problem was discovered when the weakened skin blew out, causing a drop in pressurization. The tube was 1/4" in diameter. The area where skin and stringers had been eaten away was about the size of a dinner plate. The hole would have easily passed a softball.If human urine can do it, I'm sure that pigeon poo can.Chuck (modeling Central Japan in September, 1964)
Typical reaction to this sort of thing - Ignore it, and maybe it'll go away.
Give it 40 years of not going away and the result could easily be serious degradation of the structure.
I once encountered a situation where a relief tube in the aft compartment of a KB50 had leaked undetected for an extended period of time. The problem was discovered when the weakened skin blew out, causing a drop in pressurization. The tube was 1/4" in diameter. The area where skin and stringers had been eaten away was about the size of a dinner plate. The hole would have easily passed a softball.
If human urine can do it, I'm sure that pigeon poo can.
Chuck (modeling Central Japan in September, 1964)
Hello,
I work aircraft structures for FedEx and we are involved in a situation similiar to the one Chuck speaks of. I'm repairing a 727-200 that has severe fuselage skin corrosion at the aft lavatory service panel. These panels are deactivated on our aircraft but apparently "blue water" residue from the previous operator of the aircraft seeped down between the stringers and skin and began to do it's damage. The pressure from the corrosion caused the rivit heads to shear and the fuselage skin to bulge outward. I'm now looking at about a two square foot cutout of fuselage skin which is located next to the aft pressure bulkhead, which makes this a complex repair. Waiting on Boeing engineering for a repair drawing. The stresses and pressures caused by corrosion can be enormous. I've seen corrosion areas, usually aluminum or alloy steel, bend and break stainless steel and titanium components that are rather heavy and thick.
Take care and be safe!
Gregory
Sounds to me like a case of "passing hte poop", whoops I mean "passing the buck". I recall many times my dog ate my homework during high school, but I never managed to convince my teachers to "give me a pass" for that reason.
Bucyrus wrote: But these pigeon and spider excuses are so pathetic that I am amazed they are being offered. No matter whether pigeon poop hid defects or cause them, it is the job of the state inspections authority to inspect the bridge and certify it safe. Either move the poop and look at the steel or close the bridge.
But these pigeon and spider excuses are so pathetic that I am amazed they are being offered. No matter whether pigeon poop hid defects or cause them, it is the job of the state inspections authority to inspect the bridge and certify it safe. Either move the poop and look at the steel or close the bridge.
Bucyrus has it exactly right. If necessary get a fire engine to blast the spiders and the pigeon poop out of there, or put it on a river barge to get the center sections clean; but do your job of actually inspecting the structure.
Next time it might be wise to insist on a design that is less attractive to the birds.
tomikawaTT wrote: Typical reaction to this sort of thing - Ignore it, and maybe it'll go away.Give it 40 years of not going away and the result could easily be serious degradation of the structure.I once encountered a situation where a relief tube in the aft compartment of a KB50 had leaked undetected for an extended period of time. The problem was discovered when the weakened skin blew out, causing a drop in pressurization. The tube was 1/4" in diameter. The area where skin and stringers had been eaten away was about the size of a dinner plate. The hole would have easily passed a softball.If human urine can do it, I'm sure that pigeon poo can.Chuck (modeling Central Japan in September, 1964)
How long ago did they retire the KB-50s? I am guessing it was not too long after the KC-135s came along.
"No soup for you!" - Yev Kassem (from Seinfeld)
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