Engineering Experts Knew Italian Bridge Had Corrosion Problems Before It Collapsed, Report Says (apnews.com) 141
McGruber shares a report: Engineering experts determined in February that corrosion of the metal cables supporting the Genoa highway bridge had reduced the bridge's strength by 20 percent -- a finding that came months before it collapsed last week, Italian media reported Monday. Despite the findings, newsmagazine Espresso wrote that "neither the ministry, nor the highway company, ever considered it necessary to limit traffic, divert heavy trucks, reduce the roadway from two to one lanes or reduce the speed" of vehicles on the key artery for the northern port city. A large section of the Morandi Bridge collapsed Aug. 14 during a heavy downpour, killing 43 people and forcing the evacuation of more than 600 people living in apartment buildings beneath another section of the bridge.
The other mistake (Score:4, Interesting)
If corrosion weekend the cables by 20% of so, it seems like the original design didn't leave nearly enough margin for error!
I imagine they were not as concerned with 20% weakening thinking they had much more leeway.
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I Am Not An Engineer so there's probably more involved, but "20% weakening = collapse" (as it has been implicitly presented here) does sound like they were asking for it.
That's paranoia and too much faith in planning (Score:2)
The universe is entropic (tending toward higher entropy - lower organization)
Stuff breaks down.
You don't need to plan to have things fail. They will fail by default.
All you need is insufficient planning, budget, and execution of how to make them last unexpectedly long.
Re:The other mistake (Score:4, Interesting)
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Time to accelerate those replacement plans I guess.
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It was designed by Calatrava, so no surprises there. Everything he designs falls to pieces (and/or causes accidents). Google something like "calatrava disaster", I'm sure you'll get plenty of hits.
No, I have no idea why he's so famous or why people have paid him billions to design so much stuff.
Re:The other mistake (Score:5, Informative)
It was designed by Calatrava
The Ponte Morandi bears the name of its designer:
Riccardo Morandi [wikipedia.org]
"Bridges by Morandi have proved to require extensive maintenance and repairs over the years to pass bridge safety inspections. The third span of Ponte Morandi collapsed in Genoa, on 14 August 2018, causing 43 fatalities."
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I think it was already accelerated at about 9.8 m/s^2
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I think it was already accelerated at about 9.8 m/s^2
Given the gravity of the situation, I believe you are right.
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Thanks, I actually did skim through the article for something like that but missed a Wiki link if it was there. I wonder how many other bridges are under-designed and just waiting to spring... You'd hope governments around the world would take events like this as a wake-up call to pay more attention to assessments.
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Thanks, I actually did skim through the article for something like that but missed a Wiki link if it was there. I wonder how many other bridges are under-designed and just waiting to spring... You'd hope governments around the world would take events like this as a wake-up call to pay more attention to assessments.
America's bridges are safe. President Obama spent $1 trillion on shovel-ready projects to fix all our infrastructure issues.
I-35w bridge collapse was USA's wake-up-call! (Score:3)
I-35w bridge collapse was USA's wake-up-call!
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Yeah, the design's use of prestressed concrete cables with zero redundancy is borderline baffling. It's a visually stunning design (especially given the era), but come on! I've also never seen suspension bridge (ok, technically cable-stayed bridge) where they span two suspended portions with nothing but a more-or-less standard concrete segment. Maybe this was common at one time, but most of the recent ones seem to overlap the stays.
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I've also never seen suspension bridge (ok, technically cable-stayed bridge) where they span two suspended portions with nothing but a more-or-less standard concrete segment. Maybe this was common at one time, but most of the recent ones seem to overlap the stays.
The concrete segment is a box girder albeit a very flat one. You may have seen similar spans where the traffic is inside of the box girder instead of on top but they are the same thing.
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I did not know they were box girders. It's not their use of a box girder that is unusual, it's how there are three cable-stayed sections with no overlap in stays. Not only is there no overlap, they bridge the section between cable-stayed sections with these freestanding concrete sections. If you do a Google search for cable stayed bridge, you will see almost all of them with more than one cable stayed section have significant overlap between stayed sections, or the part that it bridges is much smaller than
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I did not know they were box girders. It's not their use of a box girder that is unusual, it's how there are three cable-stayed sections with no overlap in stays. Not only is there no overlap, they bridge the section between cable-stayed sections with these freestanding concrete sections. If you do a Google search for cable stayed bridge, you will see almost all of them with more than one cable stayed section have significant overlap between stayed sections, or the part that it bridges is much smaller than what you see here. There was a very high proportion of non-stayed to stayed deck in this bridge.
I have seen them at either end of suspension bridges which use riveted girders. I suspect in this case it was done to add expansion joints between the cable stayed spans.
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Yes, but typically a suspension bridge has giant anchorages at the end. In this Italian design, it looks like the towers are free-standing (aside from the trivial amount of rigidity added by the concrete sections with expansion joints). I'm sure the math all worked out, but it does stand out in the design. I suppose it let them use lower towers to span the same distance.
Re:The other mistake (Score:5, Informative)
If corrosion weekend the cables by 20% of so, it seems like the original design didn't leave nearly enough margin for error!
I imagine they were not as concerned with 20% weakening thinking they had much more leeway.
It’s not just that, the bridge was hopelessly overloaded by traffic. There is a longstanding bypass project which has been fiercely opposed by the Five Star Movement for years. The Five Star Movement’s leaders, who now run Italy, actually cracked jokes about warnings that this bridge might collapse at regular intervals since the first warnings in 2012 or 2013. They are now trying to blame the EU (which gave them money for infrastructure sanitation) for the whole ugly mess.
Bridge engineers always consider overload (Score:3)
Itâ(TM)s not just that, the bridge was hopelessly overloaded by traffic.
Have you ever driven in New York City? Every bridge is totally full of traffic nearly 24x7, during rush hour basically parked (it took me an hour once to cross George Washington bridge leaving NYC near rush hour). That happens every day, including in driving rainstorms... bridges are usually built assuming the bridge is packed with trucks, during the worst storm imaginable (including many feet of snow, far worse than rain), then
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Yep, but when it was discovered the added an additional safety factor on top of what they had already and the cables are probably way over conservative now. Which probably is why the Brooklyn Bridge is still standing and probably will for another century.
re: cutting corners (Score:4, Informative)
One article I read said there was a good likelihood the bridge was constructed using less concrete than specified, because the mafia was heavily involved in bidding for these projects at the time. One of their favorite ways to win low bids for construction was skimping on the concrete used.
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One article I read said there was a good likelihood the bridge was constructed using less concrete than specified
Sad if so - you'd really hope there would be final checks in place to prevent things like that from crippling a major building project!
Re: cutting corners (Score:1)
The final checkers would be threatened or bribed.
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The lower level of the GWB was originally designed to hold trains. I'd imagine it's safer to be in a completely stopped traffic jam on that bridge than it would be standing on an arbitrary piece of land.
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Re:Bridge engineers always consider overload (Score:5, Interesting)
Itâ(TM)s not just that, the bridge was hopelessly overloaded by traffic.
Have you ever driven in New York City? Every bridge is totally full of traffic nearly 24x7, during rush hour basically parked (it took me an hour once to cross George Washington bridge leaving NYC near rush hour). That happens every day, including in driving rainstorms... bridges are usually built assuming the bridge is packed with trucks, during the worst storm imaginable (including many feet of snow, far worse than rain), then use safety margins well beyond that. It seems the designers of this bridge cut some corners.
I’ve driven in all kinds of places. However, the real question is: Have you ever observed the dysfunctional cocktail of corruption, populism and incompetence otherwise known as Italian politics at work? In this case you have a steadily deteriorating bridge whose load carrying capacity is rapidly decreasing, that may not have been built to specs in the first place due to corruption and that was being subjected to traffic loads and thereby vibrations that its decayed structure could not handle. And the whole time there is a political cat fight going on with a bunch of populists wingnuts who are blocking the replacement bypass project, staging protests against any repair work and ridiculing anybody who spoke out about the danger of the situation. The bottom line is that this bridge should have been replaced and decommissioned at least ten years ago.
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Iâ(TM)ve driven in all kinds of places. However, the real question is: Have you ever observed the dysfunctional cocktail of corruption, populism and incompetence otherwise known as Italian politics at work?
That's why I mentioned NYC - maybe corruption is worse in Italy than NYC, but honestly it would take more convincing,
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Links, please?
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Have you got a source for this?
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Of course not. Trolls don't have sources.
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If corrosion weekend the cables by 20% of so, it seems like the original design didn't leave nearly enough margin for error!
I imagine they were not as concerned with 20% weakening thinking they had much more leeway.
But I'm inclined to believe that they thought they had enough margin in the bridge to keep using it. The question is if they didn't understand the structural design well enough to know that 20% was dangerous, or that they underestimated the loss of strength.
Likely, the issue is a mixture of both. The engineers likely missed something important in the bridge's weakened state and the structure was substandard for the conditions. Much like the bridge that fell into the Mississippi river in the USA recentl
Re:The other mistake (Score:5, Insightful)
It's been a lot of years since engineering school, but I seem to recall the recommended safety margins for most things were 100%-500%, so yes, a 20% weakening causing collapse would be a symptom of serious under-engineering.
However, Wikipedia says this bridge is 51 years old, and that engineers have been expressing concern over its safety since the early 90s, with numerous other static and dynamic weaknesses being uncovered over the years, due to both degredation, and weakness in available computer modeling in the 60s.
Apparently traffic has quadrupled since it was built as well, so it's probably been under a lot more stress than it was really designed for. And to top it all off, eye witnesses say it was struck by lightning just before the collapse - and I would imagine conducting that kind of amperage (~30kA typical) could heat a cable enough to weaken it considerably. You'd think good engineering would factor in lightning strikes on a tall bridge like this, and they probably did, but it was probably just one stress too many on an old bridge.
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I've read about an engineering principle they used in England in the Middle Ages to make bridges safer: bridge constructors were required to sleep for two weeks under the bridge after it was constructed. With their families.
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Ponte Morandi...opened on 4 September 1967 [wikipedia.org]. So, provable safe since 18 September 1967. No need to revisit the issue, eh?
Re:The other mistake (Score:5, Insightful)
First is that the strike to the cables would not have lasted long enough to cause heat induced weakening of them, But... The high current upon entering the the wet concrete could have caused the water to flash over to steam and maybe induce cracking in the structure.
Second is the rebar embedded in the concrete supports has definitely corroded leading to weakened bonding and compromised structure internally. All concrete structures suffer this issue over time. Some deal with it by using epoxy coated rebar, some use composite rebar, and others use stainless steel to stave off this inevitable failure.
Third is that the bridge was carrying four times the original traffic it was designed for and at speeds likely far in excess of those thought prudent at the time of design and build. This again added to the stressed induced on the structure and I would submit accelerated its failure.
It is very likely that there were one or more engineers blowing the caution horn for some time now. It is also likely that they were flatly ignored, removed from the job, or sent elsewhere to silence them. Nice to see that the higher ups that lost their jobs at Morton Thiokol found new places to work and ways to kill others.
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Take a closer look at the fragments of the bridge. There is almost no rebar in the concrete. Just a thin layer near the surface and there also seems to be a hollow core in some parts.
Unless the design called for this (I doubt it), it is very likely that there was some 'optimization' going on during construction. After all, rebar is expensive and concrete costs money.
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It's been a lot of years since engineering school, but I seem to recall the recommended safety margins for most things were 100%-500%, so yes, a 20% weakening causing collapse would be a symptom of serious under-engineering.
IAAME (I Am An Mechanical Engineer). For civil engineering projects, a safety factor of 3 to 4 would be normal and more than likely would be documented
However, Wikipedia says this bridge is 51 years old, and that engineers have been expressing concern over its safety since the early 90s, with numerous other static and dynamic weaknesses being uncovered over the years, due to both degradation, and weakness in available computer modeling in the 60s.
Years after it was built, the DESIGNER of the bridge expressed concerns about its safety. Because of pollutants in the air, the weather pattern around the bridge, and the unique design of the bridge, he specifically said that corrosion on its parts was greater than he had observed in other bridges of this same design. HE warned that they really needed to watc
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These are general rule of thumb. Specific parts may have higher or lower safety margins depending on how predictable or unpreditable the stresses will be. I would imagine b
Re:The other mistake (Score:5, Interesting)
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Bridges are ugly already... sad that somebody would risk killing people to make something ugly slightly less ugly.
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Not a civil or structural engineer but I know for roofs and stuff you usually build for 1.4 times the estimated required carrying capacity (weight of covers and potential snow loads etc). That is 1.4 times the max weight you ever think you'd need to support.
Assuming the same convention is used for bridges; a 20% weakening still means it would be adequate to support loads it was designed to carry. However from the sounds of things it was also over loaded. Taken those two issues together -> problems.
Stil
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After a quick search on the bridge history, you'll see the original engineer (Riccardo Morandi) wrote about the corrosion back in 1979 and warned that it would need maintenance soon due to the sea air and pollution from a nearby steel mill.
This was the city's own fault for not following up with it for over 40 years.
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What were the error bars on the 20% estimate in the engineering study?
Could have been 20% plus or minus 10% or something like that.
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That was months before. Who knows what it was when it failed. Sometimes when things start corrode they take off like crazy. That's why preventative maintenance is important.
That makes sense (Score:1)
If the bridge was only over-engineered by 20%, then it would be a disaster to keep using it. That sounds like way too small a margin. They must have underestimated how badly damaged the cable was. If you're looking for someone to blame, it's the people who estimated the strength loss factor, not the people who did nothing once they found out.
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Unless the bridge was already built less strong than specified and the extra 20% was just the tipping point, or there were other factors involved that made the bridge collapse...
Another example: In Italy, many things are built outside specification due to mafia involvement... because taking shortcuts made it possible to pocket construction money. I'm not saying it happened here but it's just to give you another possibly 'far fetched' explanation.
You shouldn't put the blame on someone specific (also named: s
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it's the people who estimated the strength loss factor, not the people who did nothing once they found out.
They both failed at their jobs resulting in loss of life, by the sound of it. And maybe both will see jail time; after all Italy prosecuted a couple of geologists for failing to predict an earthquake.
Re:That makes sense (Score:5, Insightful)
They both failed at their jobs resulting in loss of life, by the sound of it.
If by "failed" you mean "consistently warned about the impending disaster for the past 6 year, while politicians openly mocked the warnings", then sure.
And maybe both will see jail time
Probably so. It's not like the politicians who blocked funding of an alternate route are going to let any consequences affect themselves.
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it's the people who estimated the strength loss factor, not the people who did nothing once they found out.
They both failed at their jobs resulting in loss of life, by the sound of it. And maybe both will see jail time; after all Italy prosecuted a couple of geologists for failing to predict an earthquake.
I know this is going to sound like typical American xenophobia, but it's really not. I really wish what I was going to say wasn't accurate. Given how this is Italy, like in most of the EU (I would count France and the soon to leave UK as among the few exceptions) they might convict the people involved for the loss of life, but they won't serve much time at all because in the EU there's a general belief that you have to rehab criminals and you can't actually punish them. Think I'm being ridiculous? There
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There's a recent case in Spain where some rapists got out of jail after a few months because their lawyers are appealing the verdict and it would just be too cruel to keep convicted rapists in jail while the appeal drags on.
Were they granted bail going into the trial? If so, it seems reasonable to me that if the defendant was eligible for pre-trial bail then that bail should be extended for an appeal. Reduces the chance that someone innocent spends time behind bars. Of course on the other hand they also miss out on time served if they are guilty.
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Step-dad got 10 years. Mom got about 12. Pedophile dude got about 10. And Germany says these sentences are "really long".
Considering that a human being lives about 80 years, yes, that is really long.
I'm sure about halfway through, at most, the legal system will start to feel sorry for them and they'll start getting weekend releases and so on.
And what is wrong with that? Revenge very much?
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Just a wild guess: you think that the US style federal prison, with gang rape, extortion, and senseless violence is just what the doctor ordered?
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This bullshit again? They were prosecuted for saying there was no risk and that people should go back home.
Re:That makes sense (Score:5, Informative)
If the bridge was only over-engineered by 20%, then it would be a disaster to keep using it.
It seems like the engineers have been opposed to this bridge design from the beginning, pointing out the impending disaster since 2012, and advising limiting traffic and building an alternate route. But good luck getting politicians in a democracy to spend money on infrastructure (even when given money by the EU specifically for infrastructure).
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Sure. In the meantime, let's just dismantle the EU which takes away Italy's own money, and leave it to the Italians. Then, and only then, if they won't use it to maintain their infrastructure, they'll be the ones to blame.
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It was an old bridge (circa '67), with lots of other problems too - including the fact that traffic had quadrupled since it was designed. Engineers have been expressing concerns since the 90s. And witnesses say it was also struck by lightning just before collapsing. So it wasn't a simple matter of just corrosion-weakened cables.
But yes, if it was only over-engineered by 20% it would have collapsed decades ago.
private owned toll road the profit lost from an sh (Score:2)
private owned toll road the profit lost from an shutdown is to high just fix in place.
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Italian Engineering (Score:2)
Beautiful but also fragile. See Ferrari or Lamborghini.
long time between inspections? (Score:1)
the bridge was built in the 60's and they just last year got around to inspecting it for corrosion and weakening?
Nah! (Score:2)
It's much more fun to jump on the bandwagon then to heed reason and empirical observation.
Corrosion on I-278 in Brooklyn (Score:2)
Can we stop judging before proper investigation? (Score:2)
Corrosion problems on Forth Road Bridge in Scotlan (Score:4, Interesting)
20% strength reduction from what? (Score:2)
So the bridge is 0.8 * X strong. How big is X? How big did X need to be?
A two-fold factor of safety is normal in projects like this, so if the bridge is 0.8 * X strong, it should still be 60% than it needs to be. And civil engineers tend to be a cautious lot; after several rounds of review of something like a bridge it tends to end up grossly over-designed as each engineer adds an additional margin of safety to the prior engineer's work. So there should be no way that a bridge that has lost 20% of its str
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Margins of safety and safety factors are used for several good reasons, and are used to account for aging, because of idealizations used in the calculations, or because of other uncertainties. If you think that it's OK to be below the safety factors, you're thinking wrong. Anyway, according to TFA:
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What I'm saying is that it depends on context. Nonetheless, if a 20% reduction in strength caused the bridge to fail catastrophically, then the bridge was unsafe at full strength.
The problem was known much earlier (Score:5, Informative)
The bridge's sorry state was known years ago [wptv.com]. A certain political party [wikipedia.org] used the "environmentalist" demagoguery to keep the status quo.
And now the same people are blaming the company that built and maintained the structure:
Because the government is so good at everything...
Reduce speed? (Score:2)
... or reduce the speed"
I'm having trouble figuring out how a reduce speed would reduce the load on a bridge. Anybody have an idea how that works?
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Flex. Bridges bend. So do the things on it. Gives it more time to adjust. This isn't that much of a big deal generally. There is also side load. If everything is going straight then that's fine. It's when you have a semi or some other big load and they change lanes. So you're talking say 80,000 Lbs for a fully loaded semi and now you want to move it say 20' to the right or left. Something has to exert that pressure on it. If you're going slow it's not so bad. You're still going up and down for the most part
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Really? I thought Italy was the Italy of Europe.