Genoa bridge collapse

[KeithW]

That bridge is a bit bizarre- if they could make it out of reinforced concrete they did- even the cable stays.

Though I didn't think that materials like concrete etc. performed so well in tension, even when reinforced? Then add in a harsh salty seaside location to eat away at the steel reinforcement inside over the decades...

Indeed, that might have been a concern as the eastern-most tower has seen the addition of proper cable stays?

Well as an engineer I must admit I was surprised by the bridge design. There seem to be very few stays and much of the structure appears to be sheathed in concrete which makes inspection very difficult. We know from the Severn and Forth bridges that wires in the cables can fail due to hidden corrosion but both those bridges seem to have far more redundancy, had corrosion control mechanisms installed and constant monitoring systems installed. We do have to be careful though, its possible that the failure was actually in the tower foundations especially given the heavy rain reported. More bridges collapse when the foundations are scoured away than from structural failure.

[KeithW]

I think there may be some wider concerns here that go beyond the construction and maintenance of this particular bridge.

There are a lot of spectacular motorway structures across Europe, especially in Germany, Austria and Italy, which are of a similar age to the Genoa A10 viaduct. That includes the extensive bridging and tunnelling on routes such as the Brenner autobahn and the northern Italian Autostrade but also vast numbers of big high bridges across valleys on the main German autobahn network, even away from the more challenging Alpine terrain further south.

It seems as though the big peak in construction in the late sixties and early seventies has now, half a century later, produced a correspondingly big hump in the need for maintenance, improvement and replacement of these structures. When I was on my recent circuit of Germany drive, I lost count of the number of big autobahn bridges that were contra-flowed or had lanes coned off while big remedial works were being carried out or where new construction was taking place alongside.

This does not just apply to continental Europe of course, we have our own issues with large concrete structures, not least the Huntingdon viaduct carrying the A14 and the Thelwall Viaduct where all the bearings had to be replaced.

Similar problems have occurred in the USA, the I-35W bridge collapse in Minneapolis comes to mind.
https://en.wikipedia.org/wiki/I-35W_Mis ... ver_bridge

[Bryn666]

That bridge is a bit bizarre- if they could make it out of reinforced concrete they did- even the cable stays.

Though I didn't think that materials like concrete etc. performed so well in tension, even when reinforced? Then add in a harsh salty seaside location to eat away at the steel reinforcement inside over the decades...

Indeed, that might have been a concern as the eastern-most tower has seen the addition of proper cable stays?

Well as an engineer I must admit I was surprised by the bridge design. There seem to be very few stays and much of the structure appears to be sheathed in concrete which makes inspection very difficult. We know from the Severn and Forth bridges that wires in the cables can fail due to hidden corrosion but both those bridges seem to have far more redundancy, had corrosion control mechanisms installed and constant monitoring systems installed. We do have to be careful though, its possible that the failure was actually in the tower foundations especially given the heavy rain reported. More bridges collapse when the foundations are scoured away than from structural failure.

My initial (unsubstantiated) thoughts were a failure of the foundation; noise has been made about a lightning strike but that seems unlikely to be a cause. Is it possible a slip near the foundations caused by the cloudburst and heavy rain - which were being worked on so possibly exposed - has swept the base of the tower away and brought the lot down?

[KeithW]

It is scary to think that the Morandi Bridge was still open normally last month when you see some of the photographs in this article:-

www.dailymail.co.uk/news/article-606454 ... mafia.html

In fact the cables hanging from the side were added after the bridge was build as there was concern about the condition of the original cables inside the concrete sheath as they could not be inspected. The 'spot repairs' look like expansion joint repairs that have been done on many UK structures. We really need to know where the failure started and that will take time, journalists prefer an instant talking head to careful investigation.

[Mark Hewitt]

That bridge is a bit bizarre- if they could make it out of reinforced concrete they did- even the cable stays.

Though I didn't think that materials like concrete etc. performed so well in tension, even when reinforced? Then add in a harsh salty seaside location to eat away at the steel reinforcement inside over the decades...

Indeed, that might have been a concern as the eastern-most tower has seen the addition of proper cable stays?

Well as an engineer I must admit I was surprised by the bridge design. There seem to be very few stays and much of the structure appears to be sheathed in concrete which makes inspection very difficult. We know from the Severn and Forth bridges that wires in the cables can fail due to hidden corrosion but both those bridges seem to have far more redundancy, had corrosion control mechanisms installed and constant monitoring systems installed. We do have to be careful though, its possible that the failure was actually in the tower foundations especially given the heavy rain reported. More bridges collapse when the foundations are scoured away than from structural failure.

My initial (unsubstantiated) thoughts were a failure of the foundation; noise has been made about a lightning strike but that seems unlikely to be a cause. Is it possible a slip near the foundations caused by the cloudburst and heavy rain - which were being worked on so possibly exposed - has swept the base of the tower away and brought the lot down?

Is this the tower that collapsed? https://goo.gl/maps/jNh1of7EeWR2

Looking around on google streetview at ground level, the scale of this thing in the context it sits, is stupendous.

[rhyds]

That bridge is a bit bizarre- if they could make it out of reinforced concrete they did- even the cable stays.

Though I didn't think that materials like concrete etc. performed so well in tension, even when reinforced? Then add in a harsh salty seaside location to eat away at the steel reinforcement inside over the decades...

Indeed, that might have been a concern as the eastern-most tower has seen the addition of proper cable stays?

Well as an engineer I must admit I was surprised by the bridge design. There seem to be very few stays and much of the structure appears to be sheathed in concrete which makes inspection very difficult. We know from the Severn and Forth bridges that wires in the cables can fail due to hidden corrosion but both those bridges seem to have far more redundancy, had corrosion control mechanisms installed and constant monitoring systems installed. We do have to be careful though, its possible that the failure was actually in the tower foundations especially given the heavy rain reported. More bridges collapse when the foundations are scoured away than from structural failure.

My initial (unsubstantiated) thoughts were a failure of the foundation; noise has been made about a lightning strike but that seems unlikely to be a cause. Is it possible a slip near the foundations caused by the cloudburst and heavy rain - which were being worked on so possibly exposed - has swept the base of the tower away and brought the lot down?

I couldn't work out how a lightning strike would affect anything either, as they only tend to cause heat rather than any "impact" as such. The only thing I can think of with a lighting strike is it "blowing out" a chunk of steel somewhere, but the steel would have to be very weak for that to happen.

[Bryn666]

Is this the tower that collapsed? https://goo.gl/maps/jNh1of7EeWR2

Looking around on google streetview at ground level, the scale of this thing in the context it sits, is stupendous.

Correct.

Looking at that, it's sat on hard landscaping so hard to see how a foundation may have failed - unless there were excavations.

"Maybe it just collapsed on its own" is not a good starting point is it.

[murphaph]

I couldn't work out how a lightning strike would affect anything either, as they only tend to cause heat rather than any "impact" as such. The only thing I can think of with a lighting strike is it "blowing out" a chunk of steel somewhere, but the steel would have to be very weak for that to happen.

I assumed that it would be like a tree that explodes when struck, ie water trapped behind the concrete adjacent to the fixing points and or cables themselves being turned to steam due to the lightning boiling it instantly and the steam blasting out concrete and or steel. If it was lightning at all, that is.

[Halmyre]

It is scary to think that the Morandi Bridge was still open normally last month when you see some of the photographs in this article:-

www.dailymail.co.uk/news/article-606454 ... mafia.html

In fact the cables hanging from the side were added after the bridge was build as there was concern about the condition of the original cables inside the concrete sheath as they could not be inspected. The 'spot repairs' look like expansion joint repairs that have been done on many UK structures. We really need to know where the failure started and that will take time, journalists prefer an instant talking head to careful investigation.

Hence the idiot BBC reporter yelling at the Italian PM: "Why did the bridge collapse Prime Minister?" during a press scrum.

[bothar]

Correct.

Looking at that, it's sat on hard landscaping so hard to see how a foundation may have failed - unless there were excavations.

"Maybe it just collapsed on its own" is not a good starting point is it.

You'd expect a flow of water would be needed to do real damage, but there is a road between the pier and the river channel.

Things need fixing right across Europe.
https://www.theguardian.com/world/2018/ ... rn-experts

[DavidB]

Photo slideshow from La Repubblica includes some close-up shots of one of the remaining towers as well as pictures of traffic jams in the city.

[J N Winkler]

I speculate that the collapse was caused by construction loads in combination with an as yet unknown structural defect. It has been reported that shortly before the collapse, Autostrade's contractor for the bridge retrofitting works had brought a crane onto site, as well as (IIRC) concrete barriers. This looks very similar to what happened with the I-35W bridge collapse in Minneapolis, which was ultimately traced to incorrectly designed gusset plates but which was triggered by mounds of gravel stockpiled on the deck in anticipation of a planned paving operation later the same evening.

Here is a link to the advertisement for the retrofitting contract (0200/A10):

http://www5.autostrade.it/applica/gare/ ... =IT&Lavori

The "Allegati" link opens a popup window. When the contract was still under advertisement, the window would almost certainly have included links to a ZIP archive called something like "documentazione di gara" (contract documentation), including the progetto esecutivo (including a drawings set and specification documents). Unfortunately, bidding closed last June and since Autostrade does not normally archive contract documents online, "Allegati" now leads to a bunch of Apache error messages. However, the one-page handout (link "A10 Retrofitting") is interesting. It makes it clear that Autostrade contemplated fairly extensive renovations, with a working time of 784 days and at least one full closure of the A10.

As of last night, La Repubblica was reporting that Autostrade plans to have a replacement for the missing segment in place within five months. Considering that the I-35W bridge was replaced in fourteen months even after months of time on site lost carefully removing fragments of the collapsed structure for NTSB investigation, I wouldn't say it's impossible, but it will be the civil engineering equivalent of replacing a jet engine in midair.

[BOH]

The alternative route SS1 along the seafront seems to be fully dual, so I wonder if the consideration will be that the bridge just isn't needed and that'll be that?

Absolutely not - I live 50% of my time in Genoa see my earlier reply up-thread.

The relatively new piece of D3 near the Airport that runs along the docks connects into the "Strada Sopraelevata" which is a kind of elevated inner-city by-pass of Genoa. However this has two problems, firstly is quite weight restricted so HGVs cannot use it. The second is at the eastern end it just finishes at a waterfront suburb of Genoa on the Corso Italia and through traffic would have to head through the city centre to rejoin the A10. Plus none of the western (airport) end is properly grade separated either - it was a traffic jam most of the day even before the whole of the A10 traffic was diverted onto there.

[jackal]

Highways England statement in response to Genoa bridge collapse

A statement from Highways England in response to the Genoa bridge collapse in Italy.

Published 16 August 2018
From: Highways England

Please find below the Highways England statement in response to the tragic bridge collapse in Genoa, Italy.

Highways England Chief Highways Engineer Mike Wilson said:

Our deepest sympathies are with everyone involved in the tragic bridge collapse in Genoa, Italy.

We can reassure drivers that safety is and always will be our top priority.

We have detailed design standards and quality control processes to ensure bridges are designed and constructed to provide safe and comfortable journeys for road users. This is supported by a thorough and regular regime for inspecting all structures, including bridges, on England’s motorways and major “A” roads and taking any necessary action to help ensure they stay safe.

A very small proportion of our structures are suspension or cable stayed bridges but none of them are of similar construction to the one in Genoa.

We’re committed to continually improving our network to make every journey the safest it can be. So when the causes of the Genoa bridge collapse have been investigated and reported, we will carefully assess any lessons to be learnt and will bring in any required changes to standards and processes.

Background
- there are more than 21,000 structures on England’s network of motorways and major “A” roads, none of which are of similar design to the one in Italy
- Highways England has a rigorous inspection regime for all structures, which takes into account design, age and likely maintenance needs
- general inspections are undertaken every two years with more detailed principal inspections typically every six years which involve close inspection of all parts of a structure.

https://www.gov.uk/government/news/high ... e-collapse

[Steve in Cumbria]

Interesting view of the disaster site taken from a Grauniad video. View is looking south onto the northern side of the bridge.


The forces involved must have been phenomenal for that eastern bridge deck section to have pivoted and done a 180°flip onto the railway lines (yet the deck section on the western side has just dropped 'normally' straight down).

One thing worth noting is that the structure seems to have failed on the south side first- note that the deck section embedded in the riverbed has fallen south side first, meaning the other side remained attached a fraction longer to enable the tipping movement.

Just horrific.

[Ruperts Trooper]

Interesting view of the disaster site taken from a Grauniad video. View is looking south onto the northern side of the bridge.


The forces involved must have been phenomenal for that eastern bridge deck section to have pivoted and done a 180°flip onto the railway lines (yet the deck section on the western side has just dropped 'normally' straight down).

One thing worth noting is that the structure seems to have failed on the south side first- note that the deck section embedded in the riverbed has fallen south side first, meaning the other side remained attached a fraction longer to enable the tipping movement.

Just horrific.

One of the dashcam videos shown on BBC showed the tower collapsing, very unevenly, and taking the roadway with it.

[roadtester]

It is scary to think that the Morandi Bridge was still open normally last month when you see some of the photographs in this article:-

www.dailymail.co.uk/news/article-606454 ... mafia.html

In fact the cables hanging from the side were added after the bridge was build as there was concern about the condition of the original cables inside the concrete sheath as they could not be inspected. The 'spot repairs' look like expansion joint repairs that have been done on many UK structures. We really need to know where the failure started and that will take time, journalists prefer an instant talking head to careful investigation.

Hence the idiot BBC reporter yelling at the Italian PM: "Why did the bridge collapse Prime Minister?" during a press scrum.

Why idiotic? It seems like the most obvious question to ask.

Of course, it is unlikely that anyone has the definitive answer yet, but if the PM did have something to say on the subject, the press would look like idiots if they had failed to ask the question.

[Halmyre]

In fact the cables hanging from the side were added after the bridge was build as there was concern about the condition of the original cables inside the concrete sheath as they could not be inspected. The 'spot repairs' look like expansion joint repairs that have been done on many UK structures. We really need to know where the failure started and that will take time, journalists prefer an instant talking head to careful investigation.

Hence the idiot BBC reporter yelling at the Italian PM: "Why did the bridge collapse Prime Minister?" during a press scrum.

Why idiotic? It seems like the most obvious question to ask.

Of course, it is unlikely that anyone has the definitive answer yet, but if the PM did have something to say on the subject, the press would look like idiots if they had failed to ask the question.

I seriously doubt the PM knew the answer. I also think that sort of behaviour (shouting questions at politicians) is just idiotic. Do they really think the subject of their interrogation is suddenly going to blurt out the answer? I'm all for holding politicians to account but that just isn't going to work. Sorry for the OT rant but this is one of my bugbears.

[RichardA35]

Similarly fruitless questioning on PM tonight when the Italian Red Cross were asked about the cause of the collapse.

[Johnathan404]

I seriously doubt the PM knew the answer. I also think that sort of behaviour (shouting questions at politicians) is just idiotic. Do they really think the subject of their interrogation is suddenly going to blurt out the answer? I'm all for holding politicians to account but that just isn't going to work. Sorry for the OT rant but this is one of my bugbears.

If he didn't want to be interrogated by the British press all the Italian PM had to do was walk out with a mug of tea.