Strathclyder
Established Member
Which makes far more sense to me to be totally honest, as good as the breakwater theory sounds. Was hard enough installing them in the first place.
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145 years since the Tay Bridge Disaster
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edwin_m
Veteran Member
Seems the masonry parts of the bridge were sound, but it was the ironwork that was the problem. I believe the person responsible for supervising maintenance was a masonry specialist who did what he can when the ironwork started deteriorating but didn't really understand the problem.
However, it couldn't have been totally bad, because the "low girders" were shifted across onto the new piers and as far as I know still form part of the replacement bridge. Though as this is double track there are new girders alongside them.
It was the piers being made of cast iron that was the source of the problems (apart from simply being plain inadequate to start with) - most of the defects observed were a consequence of the use of cast iron; the casting process itself was badly executed with inadequate quality control, and the design of the parts being cast incorporated various instances of bodgery which are only applicable to cast parts, and which in turn exacerbated the effect of the poor finishing of the castings and slapdash assembly of the piers. Also, of course, cast iron is a brittle material in itself.
The girders I'm pretty sure were made of wrought iron, riveted, which is a much more trustworthy material and also a more trustworthy method of construction. They were never a problem.
The girders I'm pretty sure were made of wrought iron, riveted, which is a much more trustworthy material and also a more trustworthy method of construction. They were never a problem.
Merthyr Imp
Member
That information is mentioned twice in the book 'Beautiful Railway Bridge of the Silvery Tay' by Peter R. Lewis (Tempus Publishing, 2004) which is a comprehensive history of the bridge and the disaster.
Strathclyder
Established Member
Aye, I remember reading that somewhere a few years back. Something about hammering wedges of iron into gaps in an attempt to cure 'chattering', but in doing so he ended up forcing the bridge 'out of true' and adding to it's list of problems (and doubtlessly hastening it's collapse).
I assume you mean the deck was moved across and then widened? Honestly couldn't see the original piers being reused; indeed, there's a pic of one of the 12 brick piers (on the south/Fife side) toppling into the firth with the new bridge in the foreground. See below:
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Ah I see. Is it worth picking up if one can find a copy?
edwin_m
Veteran Member
Correct. I was using "low girders" as a contrast to the "high girders", which having "with a crash given way" probably weren't in any re-useable state.
Merthyr Imp
Member
Definitely.
When looking up about the use of the remains of the old piers as breakwaters I did notice that, in relation to your above post, there was an early proposal to re-use the old piers with new piers being built alongside them to accommodate the new wider bridge.
matchmaker
Established Member
Another book worth looking for is "The High Girders", by John Prebble. Widely available.
Merthyr Imp
Member
Another point to make is that in addition to poor construction and maintenance of the bridge it didn't help when - according to several accounts - the speed limit across the bridge was frequently exceeded.
D6130
Established Member
Of course locomotives didn't have speedometers in those days. It was all down to the drivers' judgement....and in the general cacophony of noise and vibration from the bridge I imagine that it it would have been very difficult to hear the rail joints.
DerekC
Established Member
I did a bit of digging about this on the "Accidents in December" thread last year:
The collapse of the Tay Bridge forced structural design in the UK to be more of a science and less an art form and showed the effects of poor preliminary surveys and poor quality control. it shook the foundations of the Victorian age's assumptions about invincibility. That might be partly because Queen Victoria passed over it (with a good deal of ta-ra) on her way to Balmoral shortly after opening, stopping briefly in Dundee to knight the designer, Thomas Bouch. My grandparents generation (born in the 1880s and 90s) were still talking about it as if had happened quite recently.
Sir Thomas seems to get a certain amount of sympathy these days. I am not sure he deserves it. If you are interested there is a very good paper published quite recently which explains the deficiencies and the probable mechanism of collapse very clearly. Available here:
https://taybridgedisaster.com/wp-content/uploads/2023/12/iesis-paper.pdf
Edit: New link posted.
The paper explains that Sir Thomas designed the bridge on the basis of a wind load of 10 lb/sq ft distributed across the structure, which he acquired from the Astronomer Royal. It was well known by that time that wind pressures could be much higher (up to 40 to 50 lb/sq ft) in gusts and there were known experts in fluid flow whom he could have consulted. It is notable that his assistants used 20 lb/sq ft in their calculations (double what he had told them). The bridge had to be completely redesigned after construction had started because the bedrock under the Firth was much deeper down than the preliminary survey (carried out in a hurry, to a fixed price) had suggested. In redesigning the bridge with iron piers, Sir Thomas reduced the number of vertical columns from his initial intention of eight per pier to six per pier to save cost, knowing that this would reduce the stability in crosswinds. He made the critical connections between the cross-braces and the cast iron columns forming the tower members out of cast iron to save more money, yet had used wrought iron for very similar connections on the Belah viaduct, designed nearly twenty years before, with machined bearing faces to ensure that the load was distributed evenly at the critical point of the connection. (These braces would be subject to tension loads in a crosswind and cast iron is weak in tension)
The mechanism of collapse (according to the paper) was failure of the cast lugs attaching the cross-bracing ties to the columns on one of the piers under the lateral load exerted by a huge gust of wind on the train and the bridge structure, causing the pier to fall over sideways, followed immediately by progressive collapse of the rest of the piers supporting the "high girders" over the shipping channel.
The paper suggests that Bouch was under pressure from the North British Railway, which was paying, to save money but simply doesn't seem to have considered the safety implications of what he was doing.
In modern times you would expect that he would have been prosecuted for manslaughter. In those days it didn't seem to work like that. Drivers could be and were prosecuted, but not, apparently, gentleman designers!
The collapse of the Tay Bridge forced structural design in the UK to be more of a science and less an art form and showed the effects of poor preliminary surveys and poor quality control. it shook the foundations of the Victorian age's assumptions about invincibility. That might be partly because Queen Victoria passed over it (with a good deal of ta-ra) on her way to Balmoral shortly after opening, stopping briefly in Dundee to knight the designer, Thomas Bouch. My grandparents generation (born in the 1880s and 90s) were still talking about it as if had happened quite recently.
Sir Thomas seems to get a certain amount of sympathy these days. I am not sure he deserves it. If you are interested there is a very good paper published quite recently which explains the deficiencies and the probable mechanism of collapse very clearly. Available here:
https://taybridgedisaster.com/wp-content/uploads/2023/12/iesis-paper.pdf
Edit: New link posted.
The paper explains that Sir Thomas designed the bridge on the basis of a wind load of 10 lb/sq ft distributed across the structure, which he acquired from the Astronomer Royal. It was well known by that time that wind pressures could be much higher (up to 40 to 50 lb/sq ft) in gusts and there were known experts in fluid flow whom he could have consulted. It is notable that his assistants used 20 lb/sq ft in their calculations (double what he had told them). The bridge had to be completely redesigned after construction had started because the bedrock under the Firth was much deeper down than the preliminary survey (carried out in a hurry, to a fixed price) had suggested. In redesigning the bridge with iron piers, Sir Thomas reduced the number of vertical columns from his initial intention of eight per pier to six per pier to save cost, knowing that this would reduce the stability in crosswinds. He made the critical connections between the cross-braces and the cast iron columns forming the tower members out of cast iron to save more money, yet had used wrought iron for very similar connections on the Belah viaduct, designed nearly twenty years before, with machined bearing faces to ensure that the load was distributed evenly at the critical point of the connection. (These braces would be subject to tension loads in a crosswind and cast iron is weak in tension)
The mechanism of collapse (according to the paper) was failure of the cast lugs attaching the cross-bracing ties to the columns on one of the piers under the lateral load exerted by a huge gust of wind on the train and the bridge structure, causing the pier to fall over sideways, followed immediately by progressive collapse of the rest of the piers supporting the "high girders" over the shipping channel.
The paper suggests that Bouch was under pressure from the North British Railway, which was paying, to save money but simply doesn't seem to have considered the safety implications of what he was doing.
In modern times you would expect that he would have been prosecuted for manslaughter. In those days it didn't seem to work like that. Drivers could be and were prosecuted, but not, apparently, gentleman designers!
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Strathclyder
Established Member
Indeed, combine that with everything else (poor design/maintenance) and the original piers were only good for scrap.
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Noted, cheers for the recommendation.
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Genuine question, because I hadn’t realised that the Low Girders had been reused until reading this, but what kind of work would it have entailed to get them into a condition where they could last until the present day? I assume that they had many of the same problems that the ones that collapsed did?
edwin_m
Veteran Member
If I recall correctly the collapse started with the piers underneath the high girders. The girders themselves might have been fine, but only until they fell into the estuary. The low girders didn't collapse so were intact.
Merthyr Imp
Member
According to the book by Peter R. Lewis I mentioned earlier, "The undamaged girders from the old bridge were reused in the new by cutting them down the centre and widening them for the double track." No other details given, but whatever they did must have worked.
As Pigeon says in an earlier post, I don't think there was anything wrong with the bridge girders themselves, it was everything else from design onwards.
moffatcalum
Member
Some of the unused "scrap" from the old bridge was enterprisingly reused in Kinghorn at the Abden Shipyard (as a gantry crane) in the immediate aftermath of the disaster.
Furthermore, a bowstring span from the Dundee (North) side of the original bridge was repurposed and used to replace a previous wooden bridge somewhere on the Border Counties Railway, now located somewhere sumberged under the Kielder Water - I have read this before from a reliable source.
Furthermore, a bowstring span from the Dundee (North) side of the original bridge was repurposed and used to replace a previous wooden bridge somewhere on the Border Counties Railway, now located somewhere sumberged under the Kielder Water - I have read this before from a reliable source.
i have read multiple different accounts of the collapse sequence. The bridge fell from the increased side area of the train against the wind being transmitted to the leeward side rail. The bridge fell because the wind force derailed the train and it struck the high girders, knocking them off their piers. And so on ...
Is that image genuine? That seems an incredibly hazardous way of demolishing a brick pier given that there’s a brand new bridge directly alongside it!
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Merthyr Imp
Member
I think that was Sir Thomas Bouch's theory which not everyone agreed with.
What other theories were put forward as possible causes?
Wind loading on the piers was put forward as a wholly independent cause - that the bridge was simply brought down by the wind, regardless of a derailment pushing a vehicle into the girders.
I thought it was wind loading on the [wrought-iron] high girders (with a train inside adding to it) overloading the cast-iron column components which supported or held the spans in place so they snapped. I'm sure that the cast iron was both very poor quality with loads of voids - which were disguised by filling them with clay and painting over them - and was the wrong material for the job, having little strength in tension, which is what one of the modern references upthread says.
Merthyr Imp
Member
I would refer people again to the book I mentioned earlier, 'Beautiful Railway Bridge of the Silvery Tay' by Peter R. Lewis which rehearses in detail all the various theories as to what happened. There would be too much to copy out here, but it itemises poor design, faulty construction, faulty maintenance and poor operation (frequent excessive speeds across the bridge) summed up as:
"A set of design flaws produced an inherently unsafe structure at the centre of the bridge, the high girder section...It was under repeated cyclical loads and vibrations from passing trains, especially those travelling north at speed. The structure began to deteriorate rapidly. [Three months after opening] the cottered joints in the bars were starting to loosen, and the rattling sound was stopped not by retensioning the joints, but by jamming them into their loosened state with shims of iron. It allowed lateral movement of the towers of a few inches, since there was play in all the bolted joints of the structure. [A year after opening], the movement at the top of the towers when trains passed over was sufficient to alarm workers on the bridge, and travellers on the trains. A lateral wave of low frequency could be seen in the high girder section when a train travelled north at excessive speed. It was possibly induced by a slight track abnormality at the start of the high girder section.
"After a local train had experienced difficulty crossing the bridge [because of the storm] into Dundee the heavier express train which followed was allowed onto the structure despite the increasing wind speed. As it entered the high girders, it induced lateral oscillations which sent all the towers into a critical condition. The critical bracing elements in the centre of each tower had probably already been broken by the previous train, and the express was riding on two smaller towers on each pier. They probably started to collapse behind the train as it proceeded deeper into the high girders but all the towers were now unstable. They collapsed under the lateral loads from the oscillation wave, magnified by the westerly wind blowing against the train...If the centre section had not collapsed then, it would have done shortly, so rotten was its state."
"A set of design flaws produced an inherently unsafe structure at the centre of the bridge, the high girder section...It was under repeated cyclical loads and vibrations from passing trains, especially those travelling north at speed. The structure began to deteriorate rapidly. [Three months after opening] the cottered joints in the bars were starting to loosen, and the rattling sound was stopped not by retensioning the joints, but by jamming them into their loosened state with shims of iron. It allowed lateral movement of the towers of a few inches, since there was play in all the bolted joints of the structure. [A year after opening], the movement at the top of the towers when trains passed over was sufficient to alarm workers on the bridge, and travellers on the trains. A lateral wave of low frequency could be seen in the high girder section when a train travelled north at excessive speed. It was possibly induced by a slight track abnormality at the start of the high girder section.
"After a local train had experienced difficulty crossing the bridge [because of the storm] into Dundee the heavier express train which followed was allowed onto the structure despite the increasing wind speed. As it entered the high girders, it induced lateral oscillations which sent all the towers into a critical condition. The critical bracing elements in the centre of each tower had probably already been broken by the previous train, and the express was riding on two smaller towers on each pier. They probably started to collapse behind the train as it proceeded deeper into the high girders but all the towers were now unstable. They collapsed under the lateral loads from the oscillation wave, magnified by the westerly wind blowing against the train...If the centre section had not collapsed then, it would have done shortly, so rotten was its state."
edwin_m
Veteran Member
The wind loading would reach a maximum with the train in the high girders, as that combination presented the greatest area for the wind to act on. If as suggested the structure was free to sway excessively, an increase in wind strength or even the train entering the high girders would push it downwind, and a reduction in wind strength would probably cause it to recover towards its intended position. Either of these could help set up the sort of oscillation mentioned above.
matchmaker
Established Member
The notorious "Beaumonts Egg", a mixture of lampblack, beeswax, iron filings and 'Fiddler's Rosin'!
Strathclyder
Established Member
Appears to be the real deal. The water reflections seem to match the falling pier. I can't see any evidence/signs of the image being altered myself. If it had been 'photoshopped' (to use modern terms), I suspect it would've been noticed & removed by now.
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Frankly it was a miracle it lasted as long as it did before a major failure occurred, given how poorly designed, built and maintained it was. Not at all surprising that the travelling public's (and the public as a whole) confidence in Victorian engineers was thoroughly rattled and as @DerekC mentions above, it shocked them awake and forced structrual design to be more of a hard science rather than some sort of art form. Hence the Forth Bridge that opened 11 years later and is still doing what it was built to do for nearly 135 years after opening.
Overengineered that it may be, but therein lies redundancy, resilience and longevity. Much rather have that than what we got with the original Tay Bridge, cost-cutting & sloppy engineering, shoddy design work and frighteningly poor maintenance all making for a ticking time bomb strung across the Tay.
Infuriatingly tragic that it took the lives of those innocent passengers - haunts me that so many were under 30 - and train crew being so violently ended for the lessons to be learned, but such as it always is in disasters like this: 'rules and regulations are written in the blood of the innocent'. The metaphorical pen never seems to run out of ink though; lessons are forgotten or flat out ignored in the name of efficiency, profit etc and have to be painfully relearned, sometimes more than once. Not everywhere thankfully, but enough for me to be more than a little cynical.
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matchmaker
Established Member
Interestingly. I've been reading more about Thomas Bouch in "A Regional History of the Railways of Great Britain", Volume 15 - North of Scotland. He was engineer to several of the early railway companies in Fife and Tayside. The problems they had with him were shocking - he appears to have been a lousy engineer who I wouldn't have trusted to design a toast rack!
Strathclyder
Established Member
Would be fair to say the Belah Viaduct was the only major railway bridge of his that lasted any length of time.
D6130
Established Member
....plus Deepdale and Tees viaducts on the same line.
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