Engineer readers think that cable corrosion monitoring is key to preventing tragedies like last month’s collapse of the Morandi bridge in Genoa
We received 314 responses to last week’s poll on the collapse of the Morandi bridge in Genoa. There was no clear majority for any of the responses offered, but the largest group of respondents, 45%, backed the monetary installation of sensors to monitor cable corrosion in suspension-type bridges (including cable-stayed bridges, of which this was an example). The next biggest group of respondents, 27%, did not support any of our suggestions. Within a hair’s breadth of this, 26% chose the need for regulations to acquire access to load-bearing structures, while the smallest group, 2%, thought that better standards for lightning and wind shear protection would be most effective.
We published 21 comments to this poll. These tended to focus on the flaws in the bridge design. Bruce Renfrew made the point succinctly: “It was simply a flawed design – I’m surprised it passed initial scrutiny and that it lasted as long as it did.” Alfredo Clausen was more specific in his criticisms: “The catastrophe started when the (excessively) acclaimed designer became obssessed with the (ab)use of prestressed and reinforced concrete, so much that he choose to use prestressed concrete stays,” he said. “one thing is clear: he commited the sin of overconfidence (like many designers that end up feeling perfect OK with their criteria), and used TOO FEW stays, It seems Morandi disrespected any sense for the need of REDUNDANCE, and that my friends is a CAPITAL SIN in a designing engineer! Morandi can be pardoned in respect of the wrong belief that concrete was impervious to degradation, to some extent. But his use of too few stays and his insistence of using prestressing for those stays that mostly work in tension, cannot be accepted as good engineering practices.“
Some commenters raised the point that corruption may have played a role in the disaster. “Corruption is the all-pervasive problem. The love of money is the root of all evil. If cost-cutting is an overarching parameter of design, construction AND maintenance, you create the perfect storm, not the perfect bridge (or any infrastructure for that matter).” Said David Smart, who also pointed out that only four cables from each tower was inadequate support for the road deck, considering that the second Severn Crossing between England and Wales has 120 cables from each tower. A reader using the name “To be Frank” further pointed out that technological solutions may not be sufficient. “Install all the Sensors and monitoring you want. If the collected data is not analysed and the results truly acted upon they will all be worthless,” he said. “Produce endless Standards and Regulations. If they are not implemented and thoroughly checked and tested for compliance, they too will be worthless.”
Please continue to send us your opinions on this subject.
None of the above.
Personally, I’m not convinced this was necessarily an engineering failure. The design ‘seems’ to have obvious flaws but one hopes the design process addressed these issues. However, between design and implementation I would suspect, given past history, that as well as incompetence, corruption and organised crime may have played a significant part in this failure.
This bridge seems to have some design features so unusual that the true fix was probably controlled demolition and rebuild several years ago. That is a big step for anyone to take, whether government of operating company.
In the case of road/rail tunnels and bridges in mountainous areas it is phenomenally difficult to build a second bridge to enable the first to be decommissioned. In the end it must be part of the plan for all bridges, but that’s a huge cost & impact that no government or company will accept lightly.
So who accepts responsibility for the 40 Deaths.?
How many fatalities does it take to change the “accept lightly” to accept heavily and responsibly.
Are we saying that the Italian Government (local or other wise) decided that the risk was worth taking because they did not have the courage to stand up and say – sorry we have to close part of the Euro A10 Autostrada to make it safe.
We had notice in advance. We have / had both the technology and capability to fix it. All just a question of politics and money – now counted in lives lost.
Install all the Sensors and monitoring you want. If the collected data is not analysed and the results truly acted upon they will all be worthless.
Produce endless Standards and Regulations. If they are not implemented and thoroughly checked and tested for compliance, they too will be worthless. (Including falsified certification)
It was known that this bridge had problems at least for a few years in advance of the catastrophe.
Appropriate and Effective action was not taken. Why.?
The Bureaucracy that allowed this to happen needs to be hunted down and eliminated.
Saddest fact is – This Disaster was preventable.
This article adds nothing to our collective thoughts and the options are odd. Why regulations to allow access to load bearing structures? Was there an access issue and if so why is it not mentioned properly? Have you interviewed experts? They might speculate better than you… But we are not supposed to…. No wonder comment passes as fact these days.
“Why regulations to allow access to load bearing structures? Was there an access issue and if so why is it not mentioned properly?”
The cables were jacketed in concrete and therefore could not be inspected for corrosion.
Don’t think that is fully correct. We have X-Ray, Ultrasonic, Electro-magnetic and other inspection techniques all available. Not impossible, just they are much more expensive than sending a guy up on a ladder to “Look”. So it’s just down to money again.
We crossed this bridge in 2010 and my photos show it was in poor state even then, with plenty of rust stained and cracked concrete. This was in stark contrast to Switzerland, that we had just passed through. Lack of maintenance or poor standards would have been contributory factors.
None of the above.
There are many possible problems, both engineering and political, but whatever the fundamental reason for the failure, eyes-on inspection is a necessity. The encasing of the cable stays seems crazy now, but back then aesthetics may have held sway. We would pack with grease and encase in polyprop sheathing as one corrosion preventative. Another factor may have been drainage as it is well known that water and steel reinforcement are bad news. If the concrete was not made to specification, by error or intent, micro-cracking may have led to expansive corrosion.
We won’t know for some years what eventually casued the failure, but cuttting back on infrastructure inspection will lead to future disaster.
Seems the bridge had known issues, thus it was being monitored. The engineers appear to have had information but somewhere someone failed to make a correct decision. Why then is there any need for additional regulation ? I’m sure the comments about how repair or a replacement could be implemented were part of the issue but ultimately it seems, with the benefit of hindsight, that someone mad a bad decision or took a chance that didn’t pay off.
It was reported that work was underway on the tower foundations – the combination of this and the rain and wind sounds disastrous. Closure of vulnerable structures during such conditions would seem logical alongside sensing for unusual movements.
It was simply a flawed design – I’m surprised it passed initial scrutiny and that it lasted as long as it did.
Maybe more concentration on function and less on style at the design stage would have helped. The same as for the Millenium Bridge in London. Less influence by architects and more by civil engineers. I see an architect has offered his services to rebuild the bridge in Italy. No, no, no.
Architects -(formerly arch-technicians) who their fellow Freemasons believed were capable of designing arches that did not fall down! Then they put on bow-ties and went legit!
I do not wish to make jokes about what is a terrible tragedy: but as Engineers, we surely must have the final ‘say’ to ensure that the structural integrity of any item is correct: by all means ‘add’ the aesthetics later? Isn’t there another tower in Italy which is surely an example of exactly this?
From other press reports it would seem that Italy (and it is probably not alone) has many bridges in a poor state of repair and little money available to maintain or replace them. It looks like a series of avoidable failures waiting to happen but not enough resources to prevent them. Most of the suggested alternatives seem to apply mainly to new designs, not existing ones, so I fear we can expect to see more failures like Morandi.
My initial reaction was it’s far too early in the investigation to decide … now I wonder how useful findings specific to THIS tragedy will be in preventing a future disaster; rather like the adage about ‘generals always preparing to fight the last war’
With respectful condolences to those grieving, I am not a civil engineer and have no real appreciation for this particular bridge – but IMHO – Fail Safe , modular design coupled with phased inspection and repair should mitigate the worst. To paraphrase our esteemed colleague Mr.Blamey – Engineers are punished by the laws of physics if they stray, even if the mistakes are made by others – History shows time and again that until enough blood and treasure is split, nothing is changed : The great fire of London – ( and because politicians forgot and burned that red tape ) the repeat at Grenfell, Zebrugge ferry , Fukishima – I am sure others with long memories can add to the list. Perhaps of concern going forward – considering the increased probability of weather extremes indicated by global warming models – is that the design parameters of the past may not be sufficient going into the medium term future.
IMO the responsibility lies first and foremost with Morandi. Many criticised him. He designed it with 4 ‘cables’ from each tower. . . Why? The Second Severn Crossing has 120 cables from each tower. . !
An early analysis:-
https://www.nytimes.com/interactive/2018/09/06/world/europe/genoa-italy-bridge.html
“The final trick was to pretend that the borrower was Autostrade – the Italian state motorway company – when really it was IRI, a state holding company. If IRI had been the borrower, it would have had to deduct tax at source, while Autostrade did not have to.”
https://www.theguardian.com/news/2018/sep/07/the-real-goldfinger-the-london-banker-who-broke-the-world
Corruption is the all-pervasive problem. The love of money is the root of all evil. If cost-cutting is an overarching parameter of design, construction AND maintenance, you create the perfect storm, not the perfect bridge (or any infrastructure for that matter).
Engineers learned lessons from the Tay Bridge disaster but at the cost of too many lives. That failure appeared to be one of design faults, limited appreciation of wind buffetting , poor manufacturing and quality control and ineffective maintenance on the structure when it was completed. The subsequent enquiry was a whitewash.
EXACTLY!
The catastrophe started when the (excessively) acclaimed designer became obssessed with the (ab)use of prestressed and reinforced concrete, so much that he choose to use prestressed concrete stays.
Now, we don’t need to be structural engineers with a Doctorate in bridge design to understand that those concrete stays are SLENDER members, with a large lenght to gyration ratio, so that when subjected to compression (during Prestressing), those will fail is the Prestressing is high. SO, the Morandi’s Bridge stays were prestressed to a comparatively low value, which opens the real possibility of damage and degradation of the steel-cement composite. But, WHY did Morandi use prestressing in the stays in the first place? I simply CANNOT see why, unless he became too enamored with substituting as much steel as he though possible with concrete, both prestressed and plain reinforced. Reading some books written in the 60’s (badly translated from italian), one can see that Morandi was excessively praised like a brilliant, masterful bridge designer at his time in the 60’s. But one thing is clear: he commited the sin of overconfidence (like many designers that end up feeling perfect OK with their criteria), and used TOO FEW stays, It seems Morandi disrespected any sense for the need of REDUNDANCE, and that my friends is a CAPITAL SIN in a designing engineer!
Morandi can be pardoned in respect of the wrong belief that concrete was impervious to degradation, to some extent. But his use of too few stays and his insistence of using prestressing for those stays that mostly work in tension, cannot be accepted as good engineering practices. Other geometrical aspects of the failed design have been criticized recently, and can be read on the web. On the other side, if Morandi could be judged by his design, the most criminal contributions to the disaster are the politicians and the administrators of the bridge, as there were several warnings preceding the collapsethat were miserably ignored. Those who died in the bridge and their families deserve a full criminal investigation that needs to be through and impartial, as this was completely preventable. Too sad.
And vice versa! I do not wish to shine in reflected light: this was the message that Professor Dick at St Andrews offered us in 1960 in the first lecture of the first term of our first year of study: and it has remained in my mind ever since. It is the case that breaking Nature’s Laws will result in immediate detection and punishment: breaking man’s? detection and punishment appear to be optional?