Genoa Bridge Collapse Explained | WHY and HOW

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AvE : Please keep the discussion technical and respectful. Rescue work is ongoing.

KnK : Hi AvE, i'm a fan of yours and also a civil engineer from Genoa, i crossed that bridge lots and lots of times, yesterday was like a nigthmare come true... That bridge is an engineering failure presented in 1967 as a masterpiece. The situation is way more complex than you can imagine, the bridge itself was a failure from the get go, Morandi did not consider the creep of concrete leading to a deck deformation that needed lots of works to correct. Also the post-stressed concrete stays, patented by morandi himself, that in theory should have prevented the corrosion of the steel cables had shown very early problem of durability. The stays of the east tower had been reinforced with additional cables in the nineties (the collapsed section is the west one) also the bridge itself was under constant monitoring and in september should have started works for about 20 millions euros to reinforce the entire structure. That bridge was never meant to be a long term infrastructure, in fact it is in a very old part of the motorway with a lots of curves and low speed limits, and almost thirty years ago there was already a plan to bypass that entire section with a new motorway that would have allowed the demolition of the old Morandi bridge. After thirty years the politicians are still arguing about the feasibility of that bypass and no actual work has been done.... About the collapse itself, of course i do not have all the information and i can only suppose what actually happened. The collapse is of the fragile kind, no warnings and very fast kinematics, the worst kind of failure for a structure; that tells me that some steel cables snapped leading to a loss of tension in the post stressed concrete. I don't know for sure if the failure happened in one of the stay or under the deck but, looking at the debris position i'm inclined to think the failure could have been in the upper left stay, also there is a a section of the deck uspidedown and is unclear how a several tons concrete block could flip 180°, the truth i hope will be established by the Investigators.

Giaco Whatever : I’m 40 minutes from it... Let me know if you need me to go and be your eyes! I wanna know more!

Bobby Johnson Esq. : Makes you wonder about all that impressive infrastructure in China... I hope they didn't cheap out on those skyscrapers like they do the residential buildings...

Jaco Badenhorst : As a civil engineer I'm so glad that you brought up the point that we use our own structures too. One of the most difficult parts of our jobs is not the math as some would think. It's when us technical people have to explain to the beurocrats how important maintenance is. They do not understand our language. I'm not a structural engineer. I design pollution control dams on the mines here in South Africa.

Rinoa Super-Genius : Its sad how infrastructure is left to rot so much. power lines outside my house were like 100 years old and sagged so much that a quick wind would flip the wires around each other. Sewer systems are allowed to have cracks and roots growing in them. Power grid is mismanaged, Rail lines are left to rust, bridges fall down under our feet. its some truly scary shit. makes you wonder why they make bridges that fall down after 50 year that they have no intention to maintain. Your "reverse-engineering big disasters" videos are some of the best! reminds me of the old history channel called "Engineering Disasters", shame the history channel doesnt show history anymore.

The Hairy Farmer : "Ethics of our Engineers and the ethics of our Bureaucrats" - Please explain this new term - I'm in South Africa...

mathurm100 : you can go on google/maps and get really good close-up views of the structure from last fall. it looks like the rigid supports are at different angles to the main pylon (just an observation)... a LOT of corrosion. looks like it was being repaired in 2017 near the site of the collapse. it wouldn't surprise me if the 'repair' was shoddy or damaged the expansion joint. the proximity of the catastrophic collapse to some long term heavy-duty repair work has me wondering.

Andrea Florini : Italian here, this bridge and other parts of the Genova highway system where to be modernized by a new stretch of road that was designed to drastically reduce the dependence on those old and unsafe parts. The problem in Italy now is not the lack of resources but the hostility of some groups against any kind of new infrastructures, those group are heavily supported by the new populist government party (5 star movement) who main goal is the "happy degrowth". Not very long time ago there were a discussion about the future of this bridge and where the engineers pointed out the state and difficulty to maintain the bridge, one of the party spokesperson said that the possibile collapse of the bridge is only a lie told by the engineers to convince the construction of new infrastructure (NO GRONDA movement). To further understand the state of NIMBY status look for NOTAV, NOTAP, NOGRONDA(in particular to Genova) etc. all essential national and international infrastructures held hostage by a group of rock throwing popular agitator.

Eo Tunun : Bestest greetings from Tschermany! Just a remark on Italian worlmanship. That´s something I have learnt to highly respect! My main experience us from having crept under the bonnets of shitloads of cars, and I can´t help but say that, despite not having been made for mechanics, them bleedin´ Fiats and their likes are fine machines indeed. In my experience they are on par with everything made in Germany when it comes to technical failures. When it comes to small engines, I even think they offer better endurance than, for example, contemporary VW products. Mafia connected companies and maintenance, that probably is where you´ll find the actual long term source for the accumulating issues that ultimately had this bridge breaking up. Prestressed concrete buildings are demanding in mainenance, we had our own taste of that with the Berlin Congress Hall (also known as "Pregnant Oyster" to Berlinians) being the most famous structural failure here in Germany. (Soz, Wikipdeia only offered an article in German, have a look at the pictures: https://de.wikipedia.org/wiki/Kongresshalle_(Berlin)) If you read "Mafia" as feckless white-colar criminals, try to spot the actual difference between Italy and, lets say, Germany, the USA and France. Monsanto, Volkswagen, Nestlé, Swiss banks, you´ll find feckless money people with disreguard for the damage they do with their greed and good connections to politicians all over the world. So common a bit of knowledge, it´s a clichee.

Michael Mace : This was a nice video showing your human side, that you can talk about something like this without cracking jokes. I would like to thank you for your videos Ave, they bring me much joy.

analog56x : ive seen oxide jacking on vehicles before! the steering knuckles rust, and push up on the speed sensor, and trip the ABS light. tricky to figure that one out the first time, as the sensor was just replaced by another shop, and it was OEM, not aftermarket. i removed it, tested it, and it was fine. put it back in the vehicle, and not so much. i finally took a wire wheel, and hit the flat part where it bolts down to, and then it was fine. friggin rust...

Efstathios Dimopoulos : Short note about oxide jacking: The first restorer of the Parthenon in Athens in the 1920's used iron "I" shaped joints (short pieces from an I-beam). After a few years the marble cracked at the joints (oxide jacking). The ancients used different metal and filled the voids with melted lead to weather proof the joints and to add some kind of earthquake shock absorption.

Edheldui : There has to be said that Riccardo Morandi himself expressedconcerns about the cheap materials used for the bridge contruction 50 years ago. Unfortunately, cheap building materials and lack of upkeep are a plague here in Italy. Last year we had 2-3 overpasses collapse on the highway. Each one of them was 30+ years old and received no upkeep whatsoever since their contruction. On top of that, consider that when a public infrastructure needs to be built, the State makes a public downward auction, so the construction company that gets the contract is always the cheapest one, which is not necessarily (read never) the best suitable for the job.

manfred schmalbach : How could we safely repair or even properly maintain public bridges, sewers or gaslines as long as we do have to save privately owned banks, insurances and car manufacturers with public tax money? The pretty well organized crime known as "kleptocracy" is cashing in after auctioning its own grandma for nearly half a century now. It's called "neoliberalism" and "austerity" what caused this calamity.

Dave Pawson : Golden Gate has a board of directors and managers but no money to fix corrosion. Maybe get rid of the cushy well paying unnecessary board and pay the crews that work to uh....work?

Wayne Rainey : Makes you wonder what they do with our tax money? Just like in Italy, here in the USA our infrastructure is crumbling and not getting the maintenance it needs. It's like as a mechanic I remember telling this woman she only had one lug nut holding on her rear wheel and that she should buy some new ones. How much she asked, 17.95 for a packet of 4 new studs and 4 new nuts. "how long can it go like this?" she asked rather than part with the better part of $20.00. I think our politicians are doing the same with our infrastructure. I explained that by law I couldn't let her car down if I knew it was a danger to drive. well she then has a brilliant idea and says "what about this one" pointing to the front wheel which had only 3 nuts. I said 3 is not safe but provides enough strength to get the car home so her hubby could fix it. So she had me take one lug of the 2 wheels that had 4 and gave her 3 lug nuts on all wheels... I saw her a couple months later at a stop light still running 3 lugs all around!! :(

Gregor Shapiro : The bridge did not fail at the expansion joint. It came apart at the joint. The bridge failed somewhere else.

xyzyx69 : Corroding infrastructure will become a major issue in the coming decades (more so than it already is). Seems like the construction boom of the industrial age is past its expiration date. And I don't think we'll have the resources to build new, let alone maintain the old. Greedy city councils don't want to pay a living wage to tradesmen and its too easy to pass the buck and keep the change. Pretty cynical, aye? I wonder if anyone will be held accountable. Thanks all, especially you AvE.

Mari Cieli e Venti : I'm from Genoa. I used that bridge regularly as my parents did. All in Genoa knew that brigde had problems. They did a lot of work for maintenance but it has been impossible to rebuild that thing for politicals problems, environmental problems and budget, like everithing in here. Now i feel like i don't trust any other highway bridge...

iNfx1 : Can't help but agree that this design, albeit very pretty in a minimalist kind of way, was not designed with maintenance in mind. I'm from Scotland, we build fuck-off-long bridges here, it's in the blood. One of the most recent additions was a replacement to the old (1964) Forth Road bridge in Edinburgh, one of the longest suspension bridges in the world. It's called the Queensferry Crossing, and it's the absolute opposite of this design. It moves with the load and any environmental stress (it's in & over water). The towers have not 2 or 4 or 6 or 8 cable stays, instead, hundreds of cable stays per tower, per side, doubled up. The cable stays hold the bridge from the center-out, while from below it is held by the main towers and V-shaped supports to hold up the outer sections. It's about 3 kilometers long and it's an engineering marvel that cost us far too much money. But here's the difference between Scotland and Italy, it had to be done. For years we were overspending, every year we heard about them tackling the issue with corrosion on the main cable stays. It had to be replaced so the time and money was spent on something that is more fundamentally able to be maintained. Not to imply that the Italian bureaucracy were failing their own ignorance, our bridge is over water, theirs over land. We aren't able to pose the same ignorance to corrosion, partly because it's the main way into the city for many, partly because it's a much bigger job, partly because it's over water and a mistake is certainly fatal. There is naturally more urgency in our case, but at the same time, there's no reason to think a land bridge is in any lesser need of urgent replacement or maintenance, just because the damages may not be as fundamentally catastrophic as a bridge that cheats water. It's unfair to assume that it's 'less important' to know the state of the construction. I understand it, I felt uneasy going over the old Forth Road bridge every time, because of how many times a year it was reported to be corroded. Where are all the reports of this bridge being a corroded piece of shit? It's visibly corroded, why isn't there anyone coming out and saying 'oh yeah we knew it was corroded for years'? I mean look at the shitstains lads. Taking that bridge down would be as easy as putting your finger through a piece of puff pastry. There's nothing left of it and I'm certainly not impressed with the engineering. Our boy Brunel is turning in his grave at this one and with good reason.

Vaxhytron : I have a friend from Genoa (thankfully he wasn't near the bridge when the collapse happened), he says there's been talk of the bridge instability and need for repair since he was in high school (10 or more years ago?), and that the maintenance that they were doing on the bridge recently wasn't nearly enough; also it would have been hard to close that bridge for repairs since it's one of the main Italian arteries. That said most people here (in Italy) thinks this was an annunciated tragedy. Also, this is non an isolated problem, Italy is a very mountainous region, we're full of very high and very long bridges, both on the Alps and on the Apennines, and a lot of them have been in a state of reduced traffic because of bad condition and much needed repairs. More often than not the problem hasn't been the original construction but the bad or outright missing maintenance over the years.

John Aavang : So oxide expansion would be a factor as to why rusty bolts are so hard to get off? If that is correct thats pretty interesting. I knew rust made it harder to remove bolts, but I would have thought it was just the oxidation bonding the bolt to the nut or other threaded object. I suppose it could be either or both. Either way I learned something! Thanks!

Rogue Juan : Now I'm not saying lightning was the specific cause of failure, but I did happen to be looking at the live lightning strikes global map right around the time this bridge failed. That was actually the most impressive lightning storm I've caught so far on the live map. It was clocking 10-18,000 strikes per hour as the cells moved over Italy. I can't help but wonder if an unusually strong lightning bolt rode down the stay cable, and ran into a particularly rusted section of cable, if it could potentially weaken the steel even more right there. Maybe similar to how a fuse burns out with excessive amperage. One would think there is a coating on the cables, with lightning rods on top of the pylon towers to attract most bolts, but perhaps an odd bolt found a way to zap the cable. It's definitely a tough one to analyze remotely.

trombonista92 : I am Italian and I was reading the /r/Italy subreddit, there are accounts from the children of a few of the workers who built it, and from several inhabitants of the area, everyone on the job site knew full well that it would only last 50 or 60 years, and then 15 years after building it they had to start doing massive maintenance jobs, there were engineering documents from the early 2000s about how it was about to fall at any moment, published papers about it, also about 1.5 years ago a national politician went on a twetter rant about how the opposition was "blatantly lying about the ferry tale of the bridge being unsafe" , but he must have forgotten about it because 45 minutes after the collapse he twitted something along the lines of : "we came in power only 60 days ago and we stopped several disasters from happening because there were so many bridges like this that we got repaired otherwise there would have been more collapses" also the media is going nuts, speculating that it fell because "water got into the cracks and froze thereby spreading them open" some even blaming it on lightning strikes, (because you can see high voltage lines arching when the bridge falls in the video) EDIT: Its so the mafia can make money off the maintenance by the way, no one mentions it in /r/Italy because its assumed to be common knowledge EDIT2, look at it on google street view, you can see cracks and rust stains everywhere, even from the deck

Embree Smith : the Storm story is pure bullshit, the hourly weather report shows 5 mph winds .. the Structure was not designed for the weight of the Jersey Barriers placed upon it .. I have spent some 20 hours in video conferences over the last several days .. we are looking at an Eye-Bar failure causing the rotation of the failed section

Tim Finch : I wanted to hear AvE sing My Little Pony to little Chickadee!

John Carrig : Use Google Earth to take a "street view" trip across the bridge. Look up as you cross. The eastern pylon has an external repair (looks like add on external cable stays) . This seems like an attempt to patch failing concrete stays. The next pylon also seems to have repair work done at the apex though not as extensive as the eastern pylon. The pylon that failed seems to have the least amount alterations visible, but perhaps there was trouble brewing that wasn't obvious from a speeding Google camera. Another thing that struck me about this type of construction is the seeming lack of easy access to inspect the structure. Most tall suspension bridges have inspection built into the design. The date on these images is October 2017. With 20/20 hindsight it's easy to see that this piece of infrastructure was in need of replacement. Replacing a structure as large as this is both expensive and painfully inconvenient but when terrible failures like this happen, it always seems like the cheapest course would have been to act sooner to build a new bridge.

richb313 : Rain fall on bridges cause a lot more loading than people understand especially during heavy rainfalls and if drainage is compromised in any way.

Brian Garrow : Build it like your mother will use it. If you love your mother...

T Hess : Saw a bridge here in #Merica with rust streaks running down, rebar showing, and...guess how they were "repairing" it...PAINT!

Antonio Claudio Michael : That's sounds like evidence that the concerns were never addressed

Axel Montini : It collapsed because "Autostrade Per l'Italia" keeps getting richer and does no maintenance. This is what happens when roads are in the hands of private companies.

halnywiatr : The irony is that the local engineering and design talent in Genoa was focused on maritime construction and not inland on a structure exposed to the very elements that were being studied.  “Maritime Technology and Engineering” edited by Carlos Guedes Soares, T.A. Santos - 2014 - ‎Technology & Engineering; University of Genoa, Genoa, Italy “The effect of marine environment is also considered, comparing results of mechanical test on un-exposed specimens with those ... exposed to environmental effects such as salt mist spray and ultra-violet rays.”

The Big Butt Sucker : HAH in China our escalators suck pregnant women into their machinery. Yesterday a construction worker in my town committed suicide by jumping off of a beam and landed on my favorite food truck. Italy’s archaic nazi-era bridges look like bounce house shenanigans compared to the diseased, dying feral cat caked in vomit that is communist society I LOVE YOU

dtiydr : To avoid bridge corrosion: connect every rebar in concrete to each other and then connect "the other end" to a block of Zinc or other less metal and place that at a strategical place. Since Zinc is a less nobel metal then steel it will corrode first and not the rebar. Yes it have to be changed now and then since it will be consumed but its a no cost for the ordinary bridge maintenance that will cost much more.

Dru Bradley : It has been over 20 to 25 years since I was last in true red neck state of Italy, but, In one of my conversations with an old timer there, when seeing that there were building, homes & businesses the like, were the bottom (1st floor levels) windows were half below and half above the level of the sidewalks, and I had asked what kinda theory these windows offered, either for escape in case of a building fire, or was it for plumbing issues or something.. As this seemed really strange to me, because it wasn't just one building, it was many of them had this issue, where folks walking by on the sidewalk, could see right into them, and seemed like an area that stuff like garbage could get trapped, yet, kinda wasn't big enough for a person to squeeze out through... anyhow, the foundation there are always moving, and the bed rock is very deep, while having a wonderful ground water table like no other of fresh clean water (well taps). Their soil doesn't pack well. as it was something to do with the granite content in the soil. Although makes for a great filtration system for water, powdered granite is horrid to build on, as I guess it is like building on top of marbles, then throw water in the mix, and the heavy stuff on top, sinks and displaces the lighter stuff upwards.. Which is the common knowledge there, and foreign to me... I think he called the process a "Slow liquidfaction" or "liquifaction" ? They typically run pilings down 10 to 20 feet, in places like Florida or sandy soil locations, but there, due to the "granite ball bearings", in order to gain the same friction on the pilings they have to pound the pilings to 2 to 4 times the depths, of course considering what is actually being built and how heavy the super structure will be.. He also mentioned, that why the soil to bed rock is so deep, is the run off from the mountainous terrain to the lowest locations ,which is where many of Italy's main city's are built in the low laying flatter areas, as I understand it, in turn, which is where all the soil run off would collect. Here in Indiana, our bed rock of lime stone, is typically 50 to 250 feet deep, from sea level numbers, but if I remember correctly, he stated, that their granite bed rock can be a 1000 foot deep from the top surface of the over-burden top soil, and in some location twice that.. meaning, not reachable or cost effective enough to attempt to reach a sure footing. So they build, something, and hope like heck, it'll be fine, and just watch it, and deal with an issue when it shows its ugly head... I am wondering, if the bridge wasn't being pulled apart, as the ground in that location is constantly moving away from the north.. or the weight of the bases and all that sits upon the bases of this bridge, had sunk out of spec limits. But, like you had mentioned, we are not there up close to see the various connection points... and the rusting issue, I'd also place money on that, as playing a massive factor in the units issues... A scary thought, is the U.S.A.'s bridges, in huge quantity's, are in need of serious repair or replacement, literally, 1000's of them!!! I was reading an engineering book about 30 years ago, and left me with questions that I do ask folks often.. the book stated, that if a bridge doesn't move or flex, that is a dangerous bridge. If the bridge was once flexible and due from time, no longer flexible, be careful!!!.. I have talked with many about those questions, as those are legit questions, but are also unanswerable. Some bridges look to not flex, based on the type of unit it is, but then there is the type that do flex, by design. As I gather, steel units flex all over the place, and the concrete units, not so much, or any amount that can be seen with the naked eye. To consider a concrete bridge structure having any amount of flex does make me wonder of how much or how many times it can, even in the compression side of the theory. There is massive amounts of R&D on just concrete alone. but, my puny little peanut brain, has me thinking, a cylinder of HD concrete at rest, not being compressed, is one state of the concrete. Then there is that cylinder of concrete that is in the compression state, and is wonderfully strong, but then I question, what happens to that cylinder of concrete, when you remove the compression from that cylinder of concrete, does that cause stress, due from the pressure being removed, and the concrete is allowed to relax?. then I start to think, "lets do this to the cylinder of concrete 100,000 times. If concrete receives the compression and the compression is then held for 100 years, I understand, that will out last the other example, of the 1000 times over the course of 100 years, of the compression on, off, on, off, etc.... So, building a bridge, that dang big, out of high strength concrete and still having specs that the unit is allowed to flex a wee bit, either in vibrations, or twisting actions or waving actions... I don't know.. still very interesting stuff to learn about.. Please note, I am not saying building bridges out of concrete is a bad idea,, rather, I just think, thee is some engineers out there that are only hoping for the best... When considering the idea, of a design and engineering firm making the claim, that concrete will hold up to 150 years, in that type of system, just because the did a test sample the size of a can of soup, in a machine, and collectively, the age of the employees at that firm do not add up to their claim of the concrete lasting 150 years, is just strange to me, meaning, how do they factually know the concrete will hold up. predicting the future I suppose, LOL.. That is why I say ,they hope for he best and prepare for the worst. It kinda reminds me of when I was 15-1/2 years old, working at my local lumber yard, and trying to sell paint to an old farmer and his wife.. I was walking him down the lane, showing and pointing out where the 1 year paint is, and the 5 year paint is, and of course, the 35 year paint is, and went into my whole sales pitch, of how kick a$$ the 35 year warranty paint is, and that he wouldn't be sorry for spending the extra money to get it and not have to worry about paint for at least 35 years blah... blah... blah... The old farmer had a blank look on his face, and I asked him, if he had any questions, and his reply was with a question first... "Son, how old are you"... I replied, I am 15-1/2, and am working on a "workers permit, signed by my father, so I can have a job".. I didn't fully understand the direction he was going, until he then asked, simply... "Son, how do you know?".. Of course, I am now lost as to what he meant, and to which I am to answer.. I stated, that I didn't understand what he meant.. He proceeded to explain, that I am 15-1/2 years old, and trying to sell 35 year warranty paint, and asked, how do I know, that this 35 year warranty paint will last that long.... LOL.. Yes, I felt really stupid, but ,not all is lost out of that.. .as I did learn something that day... Which is, when a farmer first walks in the door, of your hardware store, and asked you to point him in the direction of the paint,, just leave him alone once you point to the location of the painting supplies and allow him to call you when he is ready to buy the paint, as he likely knows more then you, especially if you are 16 years old... LOL I suppose, there is no point to my story, but felt like giving a novel today.. I'll go find my rock now...

Andrew Beals : After the big Loma Prieta quake in '89, California (in the form of their road department, CalTrans) looked at the failures of the highway in Oakland ("The Cypress Structure") as well as the SF/Oakland Bay Bridge ("The Working Man's Bridge", perhaps soon to be known as "The Emperor Norton Bridge") and one of the things they did was to go around and retrofit every bridge with additional cable supports at the roadbed joints (expansion joints) so that if they were to be pulled apart, they wouldn't come apart and collapse, like that one section on the Bay Bridge did, collapsing at one end onto the lower deck roadbed. They did a lot of other things, and they're nicely laid out here on the CalTrans Seismic Retrofit page: http://www.dot.ca.gov/hq/paffairs/about/retrofit.htm

R - : I used to do pre stress... we did the destressing at 430 am. ..the first time I asked why only the two of us and why so early? He said so were the only two who die. Ok then... good pay at least haha

Scott Franco : We can't push this stuff off as an Italian thing. We have lots of bridges undermaintained in USA. And some have collapsed. It's a/was a very pretty bridge. We went through Genoa last year, probably went over that bridge as well.

Randy Richard In The Shop : Fair and honest discussion., well done.

Custos : You keep saying that engineers are held to a high standard, but after arguing with a civil engineer friend of mine about quality standards of manufacturing today compared to what was produced 50 years with tools these days being far closer to disposable consumables rather than serviceable quantities and him defending planned obsolescence and the circular and self-serving marketing logic of an asinine "correctly engineered items meet least cost standard0 while lasting only as long as they're engineered to last" as if I was saying everything should be made out of solid gold and last at least 1000 years after the sun burns out while costing no more than the change dug out of nephew's diaper, I can't say I was impressed with his ethics.

Some Guy : I was about to write expansion joint... but you got to it. The sections in between the pylons are drop in sections so that connection is relatively unimportant. We have had some issues with bridge sections that walk to one end of their seat and look like they would slip off. This was all from thermal cycling. The solution was to weld one side solid and let the other end move. As for the ethics. Politicians and ethics... ummmmm... yeah. As to Engineers and ethics... i personally take it very seriously... but certain other groups not so much. I know engineers that would stamp your baby for $500 cdn. Doesnt matter what scratches on a torn piece of paper you put in front of them. As to the stays. I think that is curious. Prestressed stays would be crappy since they would tend to creep slightly over time. This would open small cracks allowing moisture to the strands below. Also it would be difficult to monitor the strands and impossible to replace. If the stays were post tensioned you would likely design redundancy to allow individual strands to be removed and replaced. I looked at the photos. It looks like they used smooth bar. In the google link below you can see how much the bar slips since there is no keying action. We had seen similar situation where hooked anchor bolts pulled straight and out their holes. Notice how the bars arent broken. https://goo.gl/images/YdPbGA This means a couple things. The bars pulled out smooth... they didnt yield or neck or break. The graffiti helps line up the marks... the bars must have slipped. Fyi modern design requires the bars yield before the concrete explodes or the connections fail since this gives the most warning in case of overload. This appears to be a connection failure since you would see yielded bar or sproinged ... technically speaking term... strand. I wonder... maybe the italians used smooth bar for prestress? And relied on the anchor wedge instead of concrete bonding? If those wedges slipped... which they do that would progressively weaken the system.

andy ? : A structural engineer who lectures at Genoa University, Antonio Brencich, warned in 2016 that there were problems with the bridge, Italian media report. The bridge's designer, Riccardo Morandi (1902-1989) had miscalculated the "viscous deformation" - an ageing effect on reinforced concrete, Mr Brencich said.

Google is Evil : Lightning is questionable as a contributing factor. You can see HV electric cable short sparking in the grainy cell phone collapse video. People often mistake that for lightning strikes.

iLikeit_ : My dad is a corrosion engineer of sorts. Lives in the state of WV. Has had many emails, meetings, technical discussions about the failing and corrosion factors of wv bridges with state reps. They are so slow to move. Cheap bids and Political garbage are killing ppl.

Clitoria van Ginale : Almost fully agree with you, AvE, except for which stay gave up its duty first. I think it is the opposite side, the right front stay, because the deck is turned upside down on the railroad tracks.The road deck can only spin 180 degrees if the south eastern stay breaks first, What do you think?

QQTrick1QQ : Being in bridge repair for 10 years long ago, I've seen some pretty scary sights. This was built prior to plastic coated rebar which just slows the deterioration. I wondered how this compared to the Rt95 Greenwich Connecticut and 35W Minneapolis Minnesota bridge tragedies which were designed with no way to inspect them properly Thanks for covering this.

Lobster : In June i drove from Germany thru Austria and Switzerland to the Tuscany coast and i was shocked at the state of maintanance i was confronted with. Collapsed houses and buildings nobodys ever bothered clearing away, lots of construction sites that look like they have been abandoned for years. One particular highway offramp was so grown over it used to be 5m wide but now has little more than 2 meters left in width. I felt like i was driving thru a movie set for some sort of a post human apokalyptic szenario.

Gribble Dribble : I thought you were gonna sing London bridges.