ChrisH wrote: ↑Mon Aug 10, 2020 13:17
There are a few relevant documents about TfL's asset management, such as this from 2017 - predating the Brent Cross structures work. TfL's bid to the Major Road Network included asking for funding to fix these structures (NB this is the A406/A41 junction complex).
Yes I saw that it was built in the 1960's so hasn't done too badly.. The Staples Corner Flyover which carries the A5 was reconstructed after the 1992 IRA bombing so should be in good shape. There is a discussion about the chosen design and building method at. https://www.icevirtuallibrary.com/doi/p ... .1968.8223
The impression I got was that neither was optimal.but there were no serious concerns raised at the time. However inspection of the tendons would be good to do if possible.
Personally, I'm unconvinced that a criminal investigation and trial is the best way to deal with these kinds of failures, as unlike an independent aircrash type investigation everyone will be on much more of a defensive/adversarial posture.
That's not to say an investigation should not lead to criminal charges where they're warranted, more that it shouldn't be a case of folks feeling like they need to remain quiet to avoid possible jailtime for themselves, even if that's not actually an issue.
Personally, I'm unconvinced that a criminal investigation and trial is the best way to deal with these kinds of failures, as unlike an independent aircrash type investigation everyone will be on much more of a defensive/adversarial posture.
That's not to say an investigation should not lead to criminal charges where they're warranted, more that it shouldn't be a case of folks feeling like they need to remain quiet to avoid possible jailtime for themselves, even if that's not actually an issue.
Surely unless they can prove someone did something intentional to bring the bridge down (even as much as lack of maintenance) then a criminal trial is a bit pointless anyway.
I guess the key point is that the design of the bridge didn't really help at all, encasing the cables in concrete might provide some protection from corrosion but not totally, and at the same time making the corrosion which is there more difficult if not impossible to detect easily and monitor. It is also clearly difficult to change the cables that are corroded if they are all through concrete stays as this would probably involve lengthy closures of the bridge and also may even result in it falling down anyway.
C, E flat and G go into a bar. The barman says "sorry, we don't serve minors". So E flat walks off, leaving C and G to share an open fifth between them.
Never argue with an idiot. They will bring you down to their level and beat you with experience.
Personally, I'm unconvinced that a criminal investigation and trial is the best way to deal with these kinds of failures, as unlike an independent aircrash type investigation everyone will be on much more of a defensive/adversarial posture.
That's not to say an investigation should not lead to criminal charges where they're warranted, more that it shouldn't be a case of folks feeling like they need to remain quiet to avoid possible jailtime for themselves, even if that's not actually an issue.
IIRC Italy uses the Napoleonic system, an investigating magistrate is appointed who investigates the case. Rather than is British adversarial system where prosecution and defence presents their case to a neutral judge or jury. One of the advantages is both sides are trying to curry favour with the magistrate so answering "No Comment" to all his questions is probably not the best course of action.
If four years after the event a criminal trail is taking place then the magistrate must have enough evidence to proceed.
Is there the equivalent of Corporate Manslaughter in Italy, where a senior manager takes a commercial decision such as reducing maintenance to save money or extending the life of assets beyond its' design life as the replacement is too expensive. Expecting if it does go wrong the failure will be progressive and can be caught before killing anyone.
However, if it does not go spectacularly wrong and kills someone. Then I, personally, could face jail time for making that call, would I reconsider.
Alternatively, there could be evidence of fraudulent record keeping or other potentially criminal safety failures.
“The simple step of a courageous individual is not to take part in the lie" - Aleksandr I. Solzhenitsyn
Johnny Mo
ForestChav wrote: ↑Thu Jul 07, 2022 12:11
Surely unless they can prove someone did something intentional to bring the bridge down (even as much as lack of maintenance) then a criminal trial is a bit pointless anyway.
I guess the key point is that the design of the bridge didn't really help at all, encasing the cables in concrete might provide some protection from corrosion but not totally, and at the same time making the corrosion which is there more difficult if not impossible to detect easily and monitor. It is also clearly difficult to change the cables that are corroded if they are all through concrete stays as this would probably involve lengthy closures of the bridge and also may even result in it falling down anyway.
It doesn't work like that in Italy, take the Costa Concordia disaster, the Captain screwed up but it was not deliberate, he was handed a 16 year sentence.
In the case of the Linate airport crash they prosecuted 5 airport employees as there was no ground radar installed. In most countries such actions are seen as counter productive.
In the case of the L'Aquila earthquake they prosecuted seismologists for manslaughter on the grounds that they failed to predict it - that one eventually was thrown out after 7 years of litigation.
As for the bridge designer he has been dead for years but he had warned that the bridge was not being properly maintained. Some of the stays had been replaced or reinforced but then the money ran out.
Note that in the case of Linate the owners (the City of Milan) were NOT prosecuted for failing to provide the money for a ground radar system nor was the airport management which made it even more bizarre that they did prosecute the air traffic controllers who had to work with what they had.
JohnnyMo wrote: ↑Thu Jul 07, 2022 20:15
IIRC Italy uses the Napoleonic system, an investigating magistrate is appointed who investigates the case. Rather than is British adversarial system where prosecution and defence presents their case to a neutral judge or jury. One of the advantages is both sides are trying to curry favour with the magistrate so answering "No Comment" to all his questions is probably not the best course of action.
If four years after the event a criminal trail is taking place then the magistrate must have enough evidence to proceed.
Is there the equivalent of Corporate Manslaughter in Italy, where a senior manager takes a commercial decision such as reducing maintenance to save money or extending the life of assets beyond its' design life as the replacement is too expensive. Expecting if it does go wrong the failure will be progressive and can be caught before killing anyone.
However, if it does not go spectacularly wrong and kills someone. Then I, personally, could face jail time for making that call, would I reconsider.
Alternatively, there could be evidence of fraudulent record keeping or other potentially criminal safety failures.
This is gesture politics not justice, someone must be declared guilty but preferably no one important.
In this case they seem to have decided to prosecute every one except the company responsible, 59 people involved in maintaining the bridge are on trial but the managers at the highest level are not, reportedly an out of court settlement on that has been agreed. My contacts in Italy suggest that this what usually happens and even when jail terms are given relatively few ever actually end up saving time as the verdicts are usually thrown out on appeal or sentences reduced on appeal.
ForestChav wrote: ↑Thu Jul 07, 2022 12:11
Surely unless they can prove someone did something intentional to bring the bridge down (even as much as lack of maintenance) then a criminal trial is a bit pointless anyway.
I guess the key point is that the design of the bridge didn't really help at all, encasing the cables in concrete might provide some protection from corrosion but not totally, and at the same time making the corrosion which is there more difficult if not impossible to detect easily and monitor. It is also clearly difficult to change the cables that are corroded if they are all through concrete stays as this would probably involve lengthy closures of the bridge and also may even result in it falling down anyway.
It doesn't work like that in Italy, take the Costa Concordia disaster, the Captain screwed up but it was not deliberate, he was handed a 16 year sentence.
Slightly OT: But it was actually Jacob Rusli Bin, the helmsman, who screwed up (I'm not sure if he's ever been found after he escaped). I think from recollection he was given a bearing but set it the wrong way or something meaning the ship didn't avoid the rocks.
Schettino was in charge, though, and sometimes that is sufficient.
Of course, him abandoning ship before it had been evacuated is clearly against the law and didn't help his cause...
C, E flat and G go into a bar. The barman says "sorry, we don't serve minors". So E flat walks off, leaving C and G to share an open fifth between them.
Never argue with an idiot. They will bring you down to their level and beat you with experience.
ForestChav wrote: ↑Fri Jul 08, 2022 14:36
Slightly OT: But it was actually Jacob Rusli Bin, the helmsman, who screwed up (I'm not sure if he's ever been found after he escaped). I think from recollection he was given a bearing but set it the wrong way or something meaning the ship didn't avoid the rocks.
Schettino was in charge, though, and sometimes that is sufficient.
Of course, him abandoning ship before it had been evacuated is clearly against the law and didn't help his cause...
The Captain always carries the can, he is the one who ordered the ship to deviate from its pre planned course so he could show off to his latest girlfriend, bringing a ship that size so close the island was nuts. He was only 300 m from the shore in total darkness moving at high speed which was totally reckless.
Then there was the matter of hiring a helmsman who was Indonesian who's Italian was apparently not that good. Schettino also blamed the radar operator for not telling him he was too fast and too close to the island. What made matters worse was that while Schettino was ordering hard a port his deputy (Ciro Ambrosio) was ordering hard to starboard. It didnt matter as at that point either would have put them on the rocks.
The real issues were
1) Schettino turned off radar navigation aids and the safety systems as it would have not permitted the manoeuvre.
2) He was not wearing his reading glasses so couldn't clearly see the radar screen.
3) He didnt immediately declare an emergency and abandon ship. In calm waters close to the island there should have been plenty of time to get everyone off
I know that the original Severn Bridge, which is a very similar age to the Genoa bridge (Ponte Morandi) that collapsed, was quite unique in its engineering at the time it opened - I think it was one of the first suspension bridges to use lightweight decks that were designed with wind resistance properties without the need for a conventional triangular frame, and was also the first (and remains one of the only suspension bridges alongside the Humber Bridge) to use a triangular rather than vertical cable design, which causes it to sway a lot less than conventional suspension bridges; you can see in practice by comparing timelapse footage of the Severn/Humber bridges with the Forth Road bridge.
Has there been any evidence to suggest that the Severn Bridge was of a flawed design like the Genoa one was? I think the original Severn Bridge is perfectly safe, but since both are from the 1960s and used unique designs at the time it makes me wonder. I compared the cable design of the Severn Bridge with that of the Forth Road Bridge in a bridge simulation program and it appeared that the Severn Bridge design meant it had about 90% or so less deck motion. This makes me wonder why the Severn Bridge cable design hasn't been used on most newer suspension bridges outside of the UK even though it would be fairly easy to build a bridge with this design (the UK's Humber Bridge, which I think was designed by the same company, is the only other suspension bridge I can think of which uses the same triangular cable design and it is also very stable; the cable design patents would have expired in about the early 1980s since the patent for them dates from around 1963).
RJDG14 wrote: ↑Tue Aug 13, 2024 15:22
I know that the original Severn Bridge, which is a very similar age to the Genoa bridge (Ponte Morandi) that collapsed, was quite unique in its engineering at the time it opened - I think it was one of the first suspension bridges to use lightweight decks that were designed with wind resistance properties without the need for a conventional triangular frame, and was also the first (and remains one of the only suspension bridges alongside the Humber Bridge) to use a triangular rather than vertical cable design, which causes it to sway a lot less than conventional suspension bridges; you can see in practice by comparing timelapse footage of the Severn/Humber bridges with the Forth Road bridge.
Has there been any evidence to suggest that the Severn Bridge was of a flawed design like the Genoa one was? I think the original Severn Bridge is perfectly safe, but since both are from the 1960s and used unique designs at the time it makes me wonder. I compared the cable design of the Severn Bridge with that of the Forth Road Bridge in a bridge simulation program and it appeared that the Severn Bridge design meant it had about 90% or so less deck motion. This makes me wonder why the Severn Bridge cable design hasn't been used on most newer suspension bridges outside of the UK even though it would be fairly easy to build a bridge with this design (the UK's Humber Bridge, which I think was designed by the same company, is the only other suspension bridge I can think of which uses the same triangular cable design and it is also very stable; the cable design patents would have expired in about the early 1980s since the patent for them dates from around 1963).
We did discuss this in the topic that was raised by yourself a couple of years ago viewtopic.php?t=43873
It's very hard to state that a design of a previous age was "flawed" - it was a product of the knowledge, standards, techniques and computational power available to the designers of that time. Standards evolve over time following research and experience (including failures). Studying the designs of the bridges of the Hong Kong airport link that date from the mid 1990's and may help with how suspension bridge designs (especially as UK designers were involved) evolved after this period although, with typhoon wind loads, perhaps more robust than domestic designs.
RichardA35 wrote: ↑Tue Aug 13, 2024 16:07
Has there been any evidence to suggest that the Severn Bridge was of a flawed design like the Genoa one was? I think the original Severn Bridge is perfectly safe, but since both are from the 1960s and used unique designs at the time it makes me wonder. I compared the cable design of the Severn Bridge with that of the Forth Road Bridge in a bridge simulation program and it appeared that the Severn Bridge design meant it had about 90% or so less deck motion. This makes me wonder why the Severn Bridge cable design hasn't been used on most newer suspension bridges outside of the UK even though it would be fairly easy to build a bridge with this design (the UK's Humber Bridge, which I think was designed by the same company, is the only other suspension bridge I can think of which uses the same triangular cable design and it is also very stable; the cable design patents would have expired in about the early 1980s since the patent for them dates from around 1963).
We did discuss this in the topic that was raised by yourself a couple of years ago viewtopic.php?t=43873
It's very hard to state that a design of a previous age was "flawed" - it was a product of the knowledge, standards, techniques and computational power available to the designers of that time. Standards evolve over time following research and experience (including failures). Studying the designs of the bridges of the Hong Kong airport link that date from the mid 1990's and may help with how suspension bridge designs (especially as UK designers were involved) evolved after this period although, with typhoon wind loads, perhaps more robust than domestic designs.
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I think the problem with the Genoa bridge was its cable mechanism, which was wrapped within a single concrete covered column rather than spread out like on cable stayed bridges in the UK and in most other countries. At the time it opened I believe its design was considered a work of art. Italy has never (in the post-war era) been the best country when it comes to lasting builds, though, and the bridge collapsed due to a lack of maintenance on some of the columns that were deemed "barely at risk" during the late 1980s and early 1990s.
That said, the M48 (and former M4) Wye Bridge does have a vaugley similar design. It's different to the old Genoa bridge in that the cables are not enclosed in concrete, and that there are two from each tower instead of one.
RJDG14 wrote: ↑Tue Aug 13, 2024 16:29
I think the problem with the Genoa bridge was its cable mechanism, which was wrapped within a single concrete covered column rather than spread out like on cable stayed bridges in the UK and in most other countries. At the time it opened I believe its design was considered a work of art. Italy has never (in the post-war era) been the best country when it comes to lasting builds, though, and the bridge collapsed due to a lack of maintenance on some of the columns that were deemed "barely at risk" during the late 1980s and early 1990s.
Genoa is on the coast and from what I have seen about this incident, the bridge was designed with concrete casing around the cables not only to look good but also to contain the cables from salt water spray.
Unfortunately what they hadn't considered there is that the concrete would still allow corrosion (as we saw within other bridges where the bridge supports are encased in concrete) and that what this would mean is that whilst visible checks from the outside would look fine the cables within may in fact be quite severely corroded and that this wouldn't be obvious nor would it be easy to replace.
Actually I think they could use sound to see how corroded the cables actually were but even then this didn't show how compromised the bridge was until it collapsed.
C, E flat and G go into a bar. The barman says "sorry, we don't serve minors". So E flat walks off, leaving C and G to share an open fifth between them.
Never argue with an idiot. They will bring you down to their level and beat you with experience.
bothar wrote: ↑Tue Aug 13, 2024 21:01
Presumably cables can be waterproofed, as undersea telephone cables are. More expensive to be sure, but safe.
It's not really waterproofing though, in that sense.
It needs protecting from the salt which speeds up the rusting process and just needs iron exposed to water vapour and air.
Concrete is actually waterproof, largely speaking - that buildings and stuff are made out of it shows this - but when it gets damaged (which I think can happen by freeze/thaw action) pockets of water can get into the gaps which then get made bigger by repeated freeze/thaw, this is why concrete falls off bridges as they age, then the water and salt and everything can get into smaller areas of the cables themselves which corrodes them and the corrosion can spread to other areas of the cables.
Whether it would be possible otherwise to coat the cables in some sort of paint or similar which stops them being exposed to the elements without reducing their efficiency would be another thing but one would suspect that if this was possible there would be a high chance it would already be done. Or simply it would cost too much in comparison to replacing the cables. Undersea telecomms cables are harder to get to.
C, E flat and G go into a bar. The barman says "sorry, we don't serve minors". So E flat walks off, leaving C and G to share an open fifth between them.
Never argue with an idiot. They will bring you down to their level and beat you with experience.
One issue is with road traffic you tend to have high concentrations of sulfur from combustion engines, which makes the rain spray corrosive to concrete. In general over any urban area the rainfall will tend to have a higher concentration of sulfur than elsewhere, and this infiltrates concrete and damages the rebar and cables. The area also had some heavy industry which might have contributed some additional pollution, it's hard to say for sure.
With the cables being buried in the structure it becomes impossible to practically assess the level of damage. Old Street View images did show one span had already been reinforced due to detected damage, this span was not the one that was impacted by the collapse. One key question might be why that span was deemed at risk and the others were not - what signs were missed?
There appears to be some evidence of corrosion along one of the spans visible in historic Google Imagery. The damage may have been far worse internally.
Collapses of structures like these can occur catastrophically and without any prior warning. I'm reminded of Arecebo - the cables failed during a safety inspection by drone so we get some truly incredible footage.
The failure had been anticipated because other cables had given way already in the weeks prior, and the structure was closed due to safety concerns. But to catch the exact moment of failure is truly something.
bothar wrote: ↑Tue Aug 13, 2024 21:01
Presumably cables can be waterproofed, as undersea telephone cables are. More expensive to be sure, but safe.
It's not really waterproofing though, in that sense.
It needs protecting from the salt which speeds up the rusting process and just needs iron exposed to water vapour and air.
Concrete is actually waterproof, largely speaking - that buildings and stuff are made out of it shows this - but when it gets damaged (which I think can happen by freeze/thaw action) pockets of water can get into the gaps which then get made bigger by repeated freeze/thaw, this is why concrete falls off bridges as they age, then the water and salt and everything can get into smaller areas of the cables themselves which corrodes them and the corrosion can spread to other areas of the cables.
Whether it would be possible otherwise to coat the cables in some sort of paint or similar which stops them being exposed to the elements without reducing their efficiency would be another thing but one would suspect that if this was possible there would be a high chance it would already be done. Or simply it would cost too much in comparison to replacing the cables. Undersea telecomms cables are harder to get to.
Once undersea cables reach the ends of the useful lives, they can be abandoned (unless the copper conetn makes them worth salvaging) and nobody will really notice as they will be replaced by two or more cables, each with a much higher data throughput. If the cables are used for power transmission, then a substantial amount of copper will be used which is always worth salvaging. Moreover, power cables need t be well protected to prevent seepage as that will cause power loss and ultimately a short circuit. (See here)
The current undersea technology (I believe) is to use optic fibre for data transmission, steel for strengthening purposes and copper to provide power to repeater stations along the way. If they have the right sort of goo, they are impervious to sea-water - witness all the Lego pieces that are still being washed up on the Cornwall coast.
tom66 wrote: ↑Wed Aug 14, 2024 14:03
One issue is with road traffic you tend to have high concentrations of sulfur from combustion engines, which makes the rain spray corrosive to concrete. In general over any urban area the rainfall will tend to have a higher concentration of sulfur than elsewhere, and this infiltrates concrete and damages the rebar and cables. The area also had some heavy industry which might have contributed some additional pollution, it's hard to say for sure.
That's interesting. Perhaps it's worth adding that Genoa is far wetter than many British observers might expect; its average annual rainfall (1,247 mm) is almost double the average for Leeds (660 mm). The urban area is also packed in tightly between the sea and the mountains.
RichardA35 wrote: ↑Tue Aug 13, 2024 16:07
We did discuss this in the topic that was raised by yourself a couple of years ago viewtopic.php?t=43873
It's very hard to state that a design of a previous age was "flawed" - it was a product of the knowledge, standards, techniques and computational power available to the designers of that time. Standards evolve over time following research and experience (including failures). Studying the designs of the bridges of the Hong Kong airport link that date from the mid 1990's and may help with how suspension bridge designs (especially as UK designers were involved) evolved after this period although, with typhoon wind loads, perhaps more robust than domestic designs.
You don't have to look very far for examples of failure or potential failure. The Huntingdon Viaduct was discovered to be in poor condition which is why it had to be demolished. It had basically the same issues, steel tendons inside the concrete which were deteriorating badly due to water penetration. https://www.sabre-roads.org.uk/wiki/?ti ... he%20years.
The main problem was that the grouting of the cable strands was not done properly so corrosion was occurring which could not be repaired. That was NOT the only problem as there failures of the half joints which had to be supported by an exterior steel bracing.
Huntingdon Viaduct was a large concrete viaduct where the A14 (formerly A604) crossing of the East Coast Main Line and the B1514. The structure was both impressive and oppressive, dominating the Huntingdon skyline and carrying the dual two lane carriageway road above the B1514, which itself bridges the railway line.
The viaduct had, for many years, been deteriorating, with major remedial works carried out at various points in the years.
tom66 wrote: ↑Wed Aug 14, 2024 14:03
One issue is with road traffic you tend to have high concentrations of sulfur from combustion engines, which makes the rain spray corrosive to concrete. In general over any urban area the rainfall will tend to have a higher concentration of sulfur than elsewhere, and this infiltrates concrete and damages the rebar and cables. The area also had some heavy industry which might have contributed some additional pollution, it's hard to say for sure.
The old Wembley Conference centre had to be demolished as the roof was leaking so badly that demolition was the only option while the nearby office block where we were based had to be demolished. The old Wembley Pool on the other hand, dating back from the British Empire Exhibition is still there. https://www.google.com/maps/@51.5586022 ... &entry=ttu
Our old office building was the triangular building in this photo.
While it looked nice it turned out that deteriorating was happening under the concrete casing. In the case of the Huntingdon Viaduct the problem was detected by listening for individual strands of wire failing.
ForestChav wrote: ↑Thu Jul 07, 2022 12:11
Surely unless they can prove someone did something intentional to bring the bridge down (even as much as lack of maintenance) then a criminal trial is a bit pointless anyway.
I guess the key point is that the design of the bridge didn't really help at all, encasing the cables in concrete might provide some protection from corrosion but not totally, and at the same time making the corrosion which is there more difficult if not impossible to detect easily and monitor. It is also clearly difficult to change the cables that are corroded if they are all through concrete stays as this would probably involve lengthy closures of the bridge and also may even result in it falling down anyway.
The problem was that the limited number of stays meant that failure of a single one reduced the load carrying capability by 25% or more. There were similar problems with the original Severn crossing but it was possible to slow down the process by blowing air that had been heated and dried through the strands.
The legal/political issue with the Genoa Bridge was that the problems were known but the roads authority did not give the repairs the required priority. Italy has a major problem with bridge deterioration. https://www.csmonitor.com/World/Europe/ ... er-bridges
The sad aspect is that unlike a suspension bridge a cable stayed bridge may have a single stays replaced but not if you place aesthetics before practicality. Similar Morandi designed bridges had already failed.