Disaster by Design: The Tay Bridge Collapse

in 1879 time constraints budget restrictions inadequate design and lack of resistance to dynamic forces led to the deadly wintertime collapse on the river tay the tay bridge disaster near dundee scotland it was a windy december evening on the river tay near dundee in an area in the east of scotland just north of edinburgh where the tay meets the north sea winds well known to be high in this area frequently and on this day reaching record speeds of 50 plus miles per hour due to a major storm in the area when traversing the tay rail bridge a bridge that crosses the firth of tay at the city of dundee on the north side and the village of warmit on the south side a single track bridge at the time it was mandatory for all trains to adhere to a one train on the bridge at a time crossing system even if more than one were going in the same direction signal boxes small cabins manned by railway crews of two to three at each end would pass the baton so to speak to the currently crossing train as its token carried to the opposite end the train slowed and passed the baton back to the opposing signal box a physical indicator that the train had crossed and tracks were clear workers in the signal boxes would then communicate this to each other via telegraph wires installed along the bridge on the evening of sunday just past 1900 hours december 28 1879 darkness had set in when the steam-powered passenger train of the north british railway or nbr accelerated onto the bridge from the south side bound for dundee an express train from edinburgh with 5 passenger cars and 59 total souls aboard nbr employee john watt watched as it departed from the south signal box and witnessed a significant amount of sparks emanating from its rear car these sparks cutting through the darkness as the train faded into the distance mr watt was accustomed to seeing the trains accelerate out onto the bridge but this was concerning so dense they almost looked like flames to his eyes shortly thereafter a sudden even brighter flash of light then nothing the sparks the rear cars tail lamps the commotion all disappearing in an instant and this was much sooner than the train's lamps would normally fade into the distance as if everything vanished into darkness when the train didn't arrive at the opposite end and the signalmen attempted to contact each other communication between the signal boxes no longer functioned as if the lines had been cut the entire section of the tape ridge known as the high girders with the full length of the train inside them had collapsed into the water quite a distance to the east as if blown over by that evening's powerful winds the north british railways train had plummeted into the 30 feet deep freezing river tay crushed and effectively imprisoned by a cage of cast iron girders all souls aboard were lost [Music] mr smith the dundee station master and mr trainer a dundee locomotive foreman after hearing news from the north signal box that something was wrong took it upon themselves to venture on foot out onto the bridge it was a long precarious walk though due to such severe winds but other than the sparks mysterious disappearance and absence of the train after 35 minutes had passed observed by signalbox crews no one had any idea what had happened smith and traynor having neared what was now the end of the north section saw sloping broken rails and beyond this nothing but void not even able to see the still standing south portion through the darkness and storm rescue was attempted by boats in the area but the high winds were making this perilous as well and upon finally reaching the site no one was to be found on the surface in fact aside from the wind and waves caused by the storm the sight of the tragedy was devoid of any activity everything and everyone effectively trapped underwater one side of the high girders barely peeking above the waves in the days to follow in fact for several weeks divers recovery vessels investigators would do all they could to at least determine identities find belongings recover the bodies of the passengers but even then it was mostly girders that could be recovered in sizable pieces initially it wasn't until april of the following year that two of the carriages could even start to be lifted out of the water an eyelet a small island is now seen in the firth where no islet existed before and its component parts are loose stones fragments of iron and wood together with mangled human bodies many believe the near complete disintegration of the passenger carriages was a testament to just how weak they were in their own structure some cars reduced to what was referred to at the time as matchwood splinters so small as if to be matchsticks the locomotive would be one of the largest intact portions of the train recovered along with its coal tender car and went on to be restored and put back into service only a reported 45 victims were able to be recovered and while the original number of souls lost was thought to be roughly 75 for quite some time it was confirmed after much investigation piecing together ticket information from that day season ticket holder records and so on that 59 had been confirmed lost in this catastrophe in the 1860s competition between the two primary railways in this area of the uk the north british railway and the caledonian railway had grown fierce and whoever was first to bridge the river tay would gain a huge foothold in the control over major scotland routes nbr would choose thomas bausch for the design a renowned designer and civil engineer in his own right at the time in fact vouch had experience in building several railway branch lines already in various parts of the uk he had also proposed plans in the past to cross both the firth of fourth and tay by rail but it wasn't until the 1860s when he would be taken up on his to some at the time astonishing proposals the project from the start would be under major budget constraints add to this at two miles long the bridge had many challenges ahead the river tay even wider than the fourth at the proposed build site was well known for its frequent use by vessels of all sizes the bridge would need to be of suitable elevation to accommodate this a negotiated roughly 85 to 88 feet above the water after much back and forth with the uk's board of trade not to mention this was of course a river and rivers have currents so the exacerbated effects of scour in the bridge piers should have been accounted for as well crucially this portion of the tay was also well known by anyone who spent time in the river that during the winter and spring the winds sweeping into the delta were a force not to be taken lightly even posing a challenge to fairies and other steamers as well the original designs called for 89 spans atop solid brickwork the piers reaching upward into twin pillars of continued brickwork on each side with the longest span at a planned 200 feet at the bridge's most precipitous points the middle of the river and the deck would be wide enough for only one track instead of two tracks side by side a decision heavily criticized at the time at a cost of 217 000 sterling or roughly 26 million today construction would begin in 1871 with the work contracted out to charles de bergen company a construction firm out of the cardiff area [Music] originally a three-year deadline was provided to have the work completed and at the time for a project of this magnitude a lot to ask however the tight deadline and relatively low budget for a project of this scale would only be the beginning in this ill-fated bridge's long twisted chain of failures see preliminary borings to assess the riverbed the substrata beneath the presence and depth of bedrock were only made in the shallower portions and not continued throughout to gain a clear picture of this toward the middle of the river at its deepest points instead work would begin on piers and their foundations from the banks of the river outward based only on these preliminary findings and under the assumption that bedrock hard clay or gravel firm enough would be present at workable deaths throughout only 14 peers in though and it was discovered the hard way that sufficient substrata was suddenly at a depth inaccessible for the planned sunken brickwork foundations and as they placed pier 15 it began to lean dangerously to one side settling quickly and had to be demolished a new plan was needed since this foundation and pierce system had been the entire basis of the project incredibly the bridge would essentially need to be completely redesigned and of course with even more haste than before bouche would revise the design now from sunken tall solid brick work piers to concrete filled casings sunk 18 to 19 feet deep into the softer than predicted riverbed caseins in general are a large hollow cylinder in this instance made of a combination of iron and brickwork almost like a large hollow silo or storage tank in appearance as it's lowered into the riverbed the water the soft river bottom everything is pumped out of the casing's interior from the top as this matter is removed the weight now combined with the void of materials below allows it to sink even penetrating into the substrata eventually now with the interior devoid of any materials work can be performed effectively underwater in this instance though the cases simply backfilled with concrete once set forming a large solid pillar-like structure and the casing removed then a short brickwork base is built atop these cases followed by cast iron lattice work 80 feet in height on their own next up top the lattice work would be the girders the deck to follow that on the low girder portions and in the middle at the high girders the girders extending above the deck effectively and closing it this hollow iron lattice work would be an effort to reduce the weight on each pier others like the kremlin viaduct used this same tall cast iron lattice support system successfully but were shorter in overall length individual spans their peers more frequent and under much less dynamic force all around than the tay bridge the longest span length in the kremlin bridge for example was approximately 120 feet while bouche's designs for the tay saw the longest bands reaching an initially planned length of 200 feet while its popular belief that the quote longest bridges in the world are measured in their length from end to end in the world of bridge engineering the individual and longest spans tend to be the gauge of a bridge's level of difficulty in design and construction spans being the distance of bridge deck between each supporting pier for example the fourth bridge in outward appearance is the largest and longest cantilever bridge but the quebec bridge was known for having the longest single cantilever span i've done a video on the quebec bridge collapse and how cantilevers work if you're interested check the description for a link anyway as the taybridge's schedule became more of an issue to save time and materials the design would go from 89 spans to 85 along with pure count being decreased in the high girders increasing the distance between them from the original 200 feet to a now 245 feet in 1873 nine workers lost their lives in an explosion while excavating sand for pier number 54. the cause of the explosion was never satisfactorily ascertained it was also in 1873 after construction of the now revised version had commenced that the contracted firm the de berg company was forced to back out of the project entirely as their owner mr deberg fell victim fatally to illness the contract would then be transferred to hopkins gilks and company a firm out of middlesborough it's been said this was the largest delay in the project so far the new firm though brought quote the utmost energy to the project opening a nearby foundry in worm it to provide cast iron on the spot and by summer of 1874 the work had resumed at a rapid pace fast forward to 1877 in february when nearing completion of the high girders two of these girders fell while being put in place 80 feet up fracturing one of the pier columns all of which needing to be replaced this would delay the plans for a september opening of that year the sheer size and publicly perceived success of the project had long overshadowed any underlying issues and news had spread far and wide in addition while visiting dundee in september of that year former u.s president ulysses s grant took the time to admire the tay bridge stating it was a big bridge for a small city construction firm hopkins gilks and company giving him a tour on the nearly completed bridge and had prepared for him a handsome album containing photographs of the bridge in its various stages of construction by february of 1878 heavy ballast trains had been running over the tracks for a few months in this instance trains used for the purpose of testing and break-in periods and the bridge was ready for inspection by the railway inspectorate passing the inspection it was open to much fanfare with ceremonies held on may 31 1878 and thus opened a passenger train traffic on june 1st later that same month queen victoria would traverse the bridge by train and soon after knighthood along with heaps of praise from other prominent figures would be bestowed upon the now sir thomas bouch acknowledging his assistant colleagues as well resident engineer mr william patterson and construction managers mr albert groat and mr austin [Music] it's widely reported that high winds were a major factor in the bridge's demise just a year and a half later but what ended up being revealed after months of investigation and inquiry was quite the opposite to the portrait of success painted on opening day at first the true causes of the collapse did seem elusive but in the meantime there was also a legitimate attempt to put the blame solely on the train alone see there is a limit to the amount of wind a train can withstand and remain upright especially back then with relatively light primarily wooden passenger carriages and there were instances in other parts of the world of trains being blown off their tracks or toppled by that point the attempted narrative was to say that the bridge's integrity or lack thereof played no part in the incident and the train leaving the rails due to that night's excessive wind led to it impacting the high girders bringing the bridge down this was of course easy to dispute as every span of high girders came down as well even those where the train wasn't present collapsed as if one whole unit no there was much more to this story and the fact there was so much pride in the project as is typical with tragedies like these meant investigators had a long road ahead in getting to the truth [Music] exhaustive interviews of nearly everyone involved from construction workers to witnesses signal box workers to other train operators bore out many inconsistencies that pointed to deeper issues than one night of extreme winds indeed it turned out botcha's designs had severely underestimated wind loading factors as well the effects of oscillations or the slow back and forth vibrations caused by normal everyday usage [Music] it was discovered scour had also affected the cases something that was not accommodated for with rubble nor sheep piling later revealed was that columns had not been properly anchored down to their supports which would have protected them on the windward side from uplift the winds being almost exclusively from one side in this area blowing west to east vouch having indicated he predicted no uplift from the windward side in his designs eyewitness reports from painters and fitters stated that the high girder appears oscillated from side to side noticeably whenever trains would cross this amount of oscillation made a strong case for an additional failure point the eventual metal fatigue in the cast iron lugs that braced the lattice work to the bases [Music] in addition workers from the impromptu foundry set up in wormit testified to the effect that many of them had complaints about the quality of iron that they were given to work with in constructing the braces and latticework feeling it was rushed and the contracting supervisors requiring them to mix in scraps found around their yard of lower than typical quality some workers even complained of the rushed lugs coming out of the casting process noticeably imperfect this contract managers like mr groat outright refuted witnesses workers and other train operators would testify that trains were very long at times especially in the mornings nine or ten passenger carriages seven passenger carriages and two vans eight carriages and two vans and so on many would go on to say even drivers with confidence that speeds of 35 plus miles per hour were reached regularly even some passengers who were keen enough to detect these higher speeds when crossing had made complaints to station managers although station managers had refuted this as well speeds were recommended by the railway inspectorate and the design team to never exceed 25 miles per hour and yet since they did exceed this so often many regulars in the area would observe these oscillations both side to side and up and down becoming even more prominent the faster the trains crossed wind loading at this magnitude and almost always at right angles to the bridge heavy trains relative to the bridge frequently moving in a hurry causing oscillations and designs that severely underestimated dynamic forces like these at best meant fatigue had started to set in long before that fateful december night it was only a matter of time sir thomas bauch in his late 50s and his health ailing by the time of collapse was of the hope and insisted initially that the wind blowing the train off the tracks was the primary and only culprit not weakness in design or construction once the verdict was in as to how the collapse actually took place the committee proceedings published in august of 1880 and very much holding bounce responsible bouche's health would decline rather quickly until his death only a few months later in october of that same year many convinced he took the news of his designs playing a part in this disaster very hard we see it time and again in these stories and while it may be easy to dismiss as people back in the old days not knowing what they're doing that couldn't be further from the truth a few previous videos in this series are about events up to 140 years more modern than the tay bridge disaster sir thomas bauj was in the middle of other bridges at the time of collapse as well all of which immediately coming under scrutiny and some scrapped altogether the mighty rail bridge over the firth iv was one of them where construction was halted immediately bouche's designs had called for a suspension bridge but this was scrapped and a massive redesigned cantilever version would be undertaken by 1883 with the designs handed over to sirs john fowler and benjamin baker the fourth bridge still stands proudly to this day the new greatly reinforced tay rail bridge would be started by 1883 and it was opened by 1887 using solid masonry and iron for the piers this time and featuring a two-track wide deck these before and after photos really do show the stark reality of just how fragile that original bridge was the new bridge is still in use to this day with the old piers still present and visible alongside a very detailed memorial to the victims stands prominently nearby on the north side pointing in the direction of the high girders [Music] [Music] hey everyone i just wanted to mention how grateful i am to those who support the channel i tend to dig pretty deep and find legitimate sometimes not highly publicized information about these tragedies that i'm guessing many in related industries were expecting to either remain in the dark or many hoping they continue to fit in their little confirmation bias narrative it can and has led to some pushback on the channel so it's thanks to you the viewer the supporters and especially our very first top tier patron jenny that i can continue creating this content thanks for watching everyone and take care [Music] you

Channel: Brick Immortar

Views: 561,445

Keywords: tay bridge, bridge collapse, forensic engineering, thomas bouch, train disaster, david swinten, firth of forth, firth of tay, tay river delta, river tay, why did the tay bridge collapse, how did the tay bridge collapse, bridge disaster, structural failure, structural engineer

Id: uEgGgkTO-cw

Length: 21min 49sec (1309 seconds)

Published: Mon Sep 20 2021