Major Bridge Collapse in Genoa

[Blumf]

Whoa, this is a nasty one.

https://www.bbc.co.uk/news/world-europe-45183624

A major bridge has collapsed near the northern Italian city of Genoa, police say.

The bridge, a part of the A10 motorway, is about 100 metres tall, Italian media say - and there are unconfirmed reports that cars may have been involved.

Photographs from the scene show huge sections of rubble on the ground underneath the middle of the bridge.

Polcevera Viaduct, there were buildings under that. (Street View of the area)

[Shoulders?-Stomach!]

Fucking hell!

I have been over that one a few times, albeit not recently

[PlanktonSideburns]

albeit not recently

Oh, how convenient.

[imitationleather]

People laughed at me because of my crippling phobia of bridges. LAUGHED!

To be honest I don't mind too much because I'll take laughs where ever I can get them.

Nonetheless, this bridge collapse is horrible and is exactly what I've been fearing all these years.

[Shoulders?-Stomach!]

It is one of my recurring dreams over the years, being on the crest of a wide steep bridge and the whole thing just giving way. Not scares of bridges though: if I ever saw one I'd twat it.

[bgmnts]

Genuinely hate going over bridges for this exact reason when it popped up on my bbc news feed.

[Isnt Anything]

according to the latest bbc update - still same page - it now seems it was struck by lightning. is it possible that the current could have run down the steel reinforcing rods and superheated / exploded the concrete ?

if so then why doesnt that always happen when a bridge gets struck by lightning ?


also theres now shades of that Florida Uni pedestrian bridge collapse - 

Restructuring work on the bridge was carried out in 2016, Reuters news agency reports.

The highway operator said work to shore up its foundation was being carried out at the time of the collapse, and the bridge was constantly monitored.

[MojoJojo]

It now seems it was struck by lightning. is it possible that the current could have run down the steel reinforcing rods and superheated / exploded the concrete ?

In the wikipedia article it mentions that the cables were actually prestressed concrete instead of the more usual steel, so I guess something like you propose is a possibility.

Although it's probably a bit early to speculate meaningfully - it will probably turn out the foundations were mostly mafia informers or something.

[Isnt Anything]

In the wikipedia article it mentions that the cables were actually prestressed concrete instead of the more usual steel, so I guess something like you propose is a possibility.

Um .... but prestressed concrete wont conduct electricity. Or is that in fact the point ? maybe normally in bridges the lightning WILL run down the steel rods with no harm done (contrary to my earlier speculation) but in this case it had nowhere to go ? although presumably it must have had some form of lightning conductor on it and it must have been struck many times since the 1960s.

We need to find that same reddit engineering sub from last time, see what they have to say about it.

it will probably turn out the foundations were mostly mafia informers or something.

You jest, but if so then it might also explain it.

[buzby]

One thing I noticed in the pictures of the debris and the section that's still standing is there is black plastic mesh bolted to the underside of the deck beams and some of the support members. That's usually put thereto catch surface spalling of the concrete, either due to concrete cancer or rusting of the reinforcing steelwork. In one picture you can also see a junction box for what looks like strain gauge cables, so it was being actively monitored.

There was a local journalist on 5 Live earlier who said it's been known for decades as the 'Sick Bridge' and they have been looking at plans to replace it since the 90s. He said there was supposed to be a repair work programme starting on it next month.

[Isnt Anything]

oh just ignore me

[MojoJojo]

Um .... but prestressed concrete wont conduct electricity. Or is that in fact the point ? maybe normally in bridges the lightning WILL run down the steel rods with no harm done (contrary to my earlier speculation) but in this case it had nowhere to go ? although presumably it must have had some form of lightning conductor on it and it must have been struck many times since the 1960s.

Prestressed concrete has metal cables through it - they are what stress it. Although as you say it must have had lightning rods. I suspect the lightning might be a a red herring and buzby's old falling apart Bridge falling apart in the wind is a better explanation.

[bgmnts]

I don't know anything about construction, reinforced concrete, steel, engineering, mechanics, building or physics, but I think....

[Funcrusher]

Canary in a coalmine for an economic basket case with crumbling infrastructure?

[MojoJojo]

Canary in a coalmine for an economic basket case with crumbling infrastructure?

No.

Bridges break sometimes. It's a fairly unusual design.  I suppose the canary would be not fixing it in a reasonable timescale, or lots of other bridges/infrastructure failures indicating an inability to do proper maintenance.

You've made a big stretch to make this about continental economies. which makes me think you're a bit of a nationalistic arsehole. And I made a mafia joke about it.

[Shoulders?-Stomach!]

Should we nationalise arseholes? Discuss

[Funcrusher]

You've made a big stretch to make this about continental economies. which makes me think you're a bit of a nationalistic arsehole.

Nah. The Italian banking sector is often cited as being particularly shaky and the potential first domino to fall in the next financial crisis - equally it wouldn't surprise me if it was Britain. A film like Sorrentino's 'The Great Beauty' suggests a country that is corrupt and decaying. My post had a question mark after it because it's hard to tell where Italy is really at.

[MojoJojo]

Nah. The Italian banking sector is often cited as being particularly shaky and the potential first domino to fall in the next financial crisis - equally it wouldn't surprise me if it was Britain. A film like Sorrentino's 'The Great Beauty' suggests a country that is corrupt and decaying. My post had a question mark after it because it's hard to tell where Italy is really at.

Yes, that's all going on about Italy's economy, which I'm not going to pretend I can say anything about.

It's obviously what you want to talk about, but doesn't really have anything to do with the bridge collapse in Genoa that this thread is about.

Is there any evidence the collapse was caused by under spending on maintenance caused by an inefficient economy?

Your first post mentioned canaries - the point being they were (somewhat) reliable indicators. Can you give any examples of a state failing from a single civil engineering failure?

You've jumped on a hobby horse about the italian economy which has no relevance to the thread.

[Dex Sawash]

. Can you give any examples of a state failing from a single civil engineering failure?

Had Sealand fallen over yet?

[bgmnts]

Grenfell? If that counts.

[Fambo Number Mive]

No.

Bridges break sometimes. It's a fairly unusual design.  I suppose the canary would be not fixing it in a reasonable timescale, or lots of other bridges/infrastructure failures indicating an inability to do proper maintenance.

You've made a big stretch to make this about continental economies. which makes me think you're a bit of a nationalistic arsehole. And I made a mafia joke about it.

I don't want to take away from a tragedy that caused the death of 35 people, but I hardly think being critical of the Italian economy makes Funcrusher what you called him above. He's not even making it about continental economies, but specifically Italy's economy.

This is the fifth bridge collapse in Italy in five years, according to Corriere Della Serra.

[the]

This is a terrible catastrophic incident, yet simultaneously it keeps making me think of a nice slice of Genoa cake with a cup of tea. Have any of your readers been inappropriately reminded of cake varieties by tragic incidents?

[buzby]

Grenfell didn't fail structurally, which is one thing to be thankful for.

Having a look at the bridge on Streetview, it seems there have already been structural problems with the concrete 'cable stays'. The concrete stays on the easternmost tower (which stands over the most populated area) were encased with steel rope tendons in 1993 due to concerns about their condition. The walls on the edges of the deck also show signs of severe rusting and spalling too. The same remedial work in 1993 also added steel jackets around the the cable stay connections at the tops of the other pylons (including the one that collapsed) too:

From Kristian Hasenjäger's retrofutur blog, which contains some interesting pictures of the bridge taken a few years ago, including the spall netting patches applied ot the undersides of the deck:


The bridge's architect Riccardo Morandi also had  a longer version of this design (with 6 pylons instead of 3) built in Venezuela, the Lake Maracaibo bridge, which had all the concrete stays replaced with steel cables about 5 years ago due to concerns about their condition. It seems he encased the steel stay cables in concrete as corrosion protection, but this removed the ability for them to be checked for corrosion.

They were obviously doing work on the deck in 2017, hence the temporary concrete barriers. That lines up with one of the reports which said "work was underway to consolidate the viaduct slab and, as planned, a bridge crane had been installed to allow maintenance activities to take place".

[Uncle TechTip]

Somewhat unfair on Funcrusher, and I detect something of the easy target about those attacks. The Italian president himself has said that the people have the right to maintained infrastructure, something you wouldn't think he'd say if this was an anomaly.

The president, Sergio Mattarella, expressed his condolences in a statement, while stressing that Italians should be guaranteed the right "to modern and efficient infrastructure that accompanies everyday life".

[MojoJojo]

Sorry, probably going over board.

[Porter Dimi]

Tom Bradby's reporting of the disaster on ITV News at Ten is a little too close to Chris Morris for comfort https://twitter.com/DG_Hayden/status/1029474456845131779

[MojoJojo]

Apparently there was maintenance work being carried out on the foundations of the tower - with the heavy rain at the time, I think that has to be considered the failure point.

[buzby]

Apparently there was maintenance work being carried out on the foundations of the tower - with the heavy rain at the time, I think that has to be considered the failure point.

I think that may be a mistranslation of the Italian reports and it was actually the bridge deck that was being worked on - a tower crane was brought in as part of the works, which wouldn't be required for working on the foundations.

After studying the Google streetview images a bit more, it seems the steel reinforcing jackets were only placed on top ends of the stays of the central pylon during the works in the 1990s. The west pylon had no reinforcing work performed on it, and on the Streetview images there is some of the spall netting attached to the tops of the stays, which is a bad sign.

The retrofutur page i linked to earlier originally had a link to an Italian article by Professor Giovanna Franco about the history of the constant remediation work necessary on the bridge (including the 1993 work done to augment the cable stays on the east pylon) due to the construction method used by Morandi and the presence of salt air, bur it was removed soon after the collapse (supposedly it was an internal document that should not have been publically available). It's still there on the wayback machine though, and van be read via Google Translate here

The company that runs the Autostrada put out a request for tender in May for a 20 million euro contract to replace the concrete stays on all the towers (as had been done on it's larger sister in Venezuela), with a target of work starting in the autumn. They obviously knew they had structural problems, but it seems they may have left it just a little too late to do anything.

There also seems to be a lack of oversight of the Autrostrada regarding structural checks. Any structure built before the 90s doesn't need to have a maintenance plan lodged with the Transport Ministry. The operator is supposed to do quarterly visual inspections (using their own engineers) and detailed structural surveys every 2 years (usually performed by an outside contractor survey company), but they don't have to publish the results to the local or national government agencies, and they sign off their own safety certification.

[buzby]

Apologies for the thread resurrection, but I found some interesting research that was performed in the wake of the collapse of this bridge.

A group of scientists have used the historical data from the very accurate radar used by ground mapping satellites to plot the state of the bridge between August 2009 and it's collapse in June 2018.
https://www.mdpi.com/2072-4292/11/12/1403
Between August 2009 and March 2017 the bridge deck height had dropped by 60mm, and between March 2017 and it's collapse it dropped a further 60mm, the sudden increase pointing towards serious structural problems. There is also an video plotting the readings and displaying the levels of the deck sections under each of the 3 pylons.

As measured by the satellites, all three deck sections had gone through asymmetric conditions during this time period, but the westernmost section (the one which collapsed) had an increasing tilt towards it's western side from around the beginning of 2013, with the angle of tilt increasing rapidly from March 2017. Interestingly, a new CCTV video was released by the investigators at the end of July, taken from a camera on the engineering company warehouse on the western bank of the river  that shows the concrete-encased cable stays on the western side of the west pylon were what gave way first, with the pylon then being torn down by the resulting asymmetric overload.

The remaining structure was demolished using explosives at the end of June. Tanks of water were placed on the decks and around the bases of the pylons that were also detonated with explosives, generating a curtain of water intended to contain the dust from the explosion.

[Blumf]

That's impressive, getting those measurements from afar, but didn't the bridge have sensors on it? Seems like something the people charged with maintaining it would have have wanted for this exact reason, especially as it was known to be in a bad state.