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Tay Rail Bridge

The Tay Bridge (sometimes unofficially the Tay Rail Bridge) is a railway bridge approximately two and a quarter miles (three and a half kilometres) long that spans the Firth of Tay in Scotland, between the city of Dundee and the suburb of Wormit in Fife ().

As with the Forth Bridge, the Tay Bridge has also been called the Tay Rail Bridge since the construction of a road bridge over the firth, the Tay Road Bridge. The rail bridge replaced an early train ferry.

The first Tay Bridge

The original Tay Bridge was designed by noted railway engineer Thomas Bouch, who received a knighthood following the bridge's completion. It was a lattice-grid design, combining cast and wrought iron. The design was well known, having been used first by Kennard in the Crumlin Viaduct in South Wales in 1858, following the innovative use of cast iron in The Crystal Palace. However, the Crystal Palace was not as heavily loaded as a railway bridge. A previous cast iron design, the Dee bridge which collapsed in 1847, failed due to poor use of cast-iron girders. Later, Gustave Eiffel used a similar design to create several large viaducts in the Massif Central (1867).

Proposals for constructing a bridge across the River Tay date back to at least 1854. The North British Railway (Tay Bridge) Act received the Royal Assent on 15 July 1870 and the foundation stone was laid on 22 July 1871. As the bridge extended out into the river, it shortly became clear that the original survey of the estuary had not been competent. The bedrock, at a shallow depth near the banks, was found to descend deeper and deeper, until it was too deep to act as a foundation for the bridge piers. Bouch had to redesign the piers, and to set them very deep in the estuary bed to compensate for having no support underneath. He also reduced the number of piers by making the spans of the superstructure girders much longer than before. This made them greater than the maximum length without taking into account wind loadings.

The first engine crossed the bridge on 22 September 1877, and upon its completion in early 1878 the Tay Bridge was the longest in the world. The bridge was opened on 1 June 1878.

While visiting the city, Ulysses S. Grant commented that it was "a big bridge for a small city".

The Tay Bridge Disaster

During a violent storm on the evening of 28 December 1879, the centre section of the bridge, known as the "High Girders", collapsed, taking with it a train that was running on its single track. Seventy-five lives were lost, including that of Sir Thomas's son-in-law. The total number was only established by a meticulous examination of ticket sales, some from as far away as King's Cross. Forty-six of the sixty known victims were found, with two bodies not being recovered until February 1880.A common 19th century urban myth in Dundee was that Karl Marx would have been a passenger on the fatal train of 1879 had illness not prevented him from travelling.

Investigators quickly determined many faults in design, materials, and processes that had contributed to the failure. No allowance for wind load had been made by Bouch: he had been advised that this was unnecessary for girders shorter than 200ft, and had not followed this up for his new design with longer girders. The section in the middle of the bridge, where the rail ran inside high girders (through trusses), rather than on top of lower ones (deck trusses), to allow a sea lane below high enough for the masts of ships, was potentially top heavy and very vulnerable to high winds. Neither Bouch nor the contractor appeared to have regularly visited the on-site foundry where iron from the previous half-built bridge was recycled. The cylindrical cast iron columns supporting the 13 longest spans of the bridge, each 245 ft (75 m) long, were of poor quality. Many had been cast horizontally, with the result that the walls were not of even thickness, and there was some evidence that imperfect castings were disguised from the (very inadequate) quality control inspections. In particular, many of the lugs used as attachment points for the wrought iron bracing bars had been "burnt on" rather than cast with the columns. However, no evidence of the burnt-on lugs has survived, and the normal lugs were very weak. They were tested for the Inquiry by David Kirkaldy and proved to break at only rather than the expected load of . It is believed that, during the storm, these lugs failed and destabilised the entire centre part of the bridge.

Official enquiry

The official enquiry was chaired by Henry Cadogan Rothery, Commissioner of Wrecks, supported by Colonel Yolland (Inspector of Railways) and civil engineer William Henry Barlow. They concluded that the bridge was "badly designed, badly built and badly maintained, and that its downfall was due to inherent defects in the structure, which must sooner or later have brought it down".

There was clear evidence that the central structure had been deteriorating for months before the final accident. The maintenance inspector, Henry Noble, had heard the joints of the wrought-iron tie-bars "chattering" a few months after the bridge opened in June 1878, a sound indicating that the joints had loosened. This made many of the tie-bars useless for bracing the cast-iron piers. Noble did not attempt to re-tighten the joints, but hammered shims of iron between them in an attempt to stop the rattling.

The problem continued until the collapse of the High Girders. It indicated that the centre section was unstable to lateral movement, something observed by painters working on the bridge in the summer of 1879. Passengers on north-bound trains complained about the strange motion of the carriages, but this was, apparently, ignored by the bridge's owners, the North British Railway. The Lord Provost of Dundee had reportedly timed trains on the bridge, and found they were travelling at about , well in excess of the official limit of .

The enquiry destroyed Bouch's professional reputation: "For these defects both in the design, the construction and the maintenance, Sir Thomas Bouch is, in our opinion, mainly to blame. For the faults of design he is entirely responsible". The Board of Trade, concerned about Bouch's design for the planned Forth Rail Bridge on the same railway line, imposed a specification of 56 pounds force per square foot (2.7 kPa). The contract for the new Forth Bridge was awarded to William Arrol & Co. using designs by Benjamin Baker and John Fowler. Bouch died within a year of the disaster.

J. N. C. Law, in a comprehensive article in the Railway Magazine (P160 March 1965), suggested there was strong evidence that the wind pressure would have blown the train over before it would have brought the bridge down. He cites several incidents where the lighter rolling stock of that era was blown over, leaving only the heavier locomotive (at the front of the train) on the rails. The whole train weighed only 115 tons and the second class coach (fifth out of six coaches) had a weight of under six tons. The inquiry had estimated that a wind force of 36.6 lb/sq ft would be required to topple this particular coach, but Law's re-estimate was 27.7 lb/sq ft. Amongst other factors his re-estimate does not assume even distribution of the passengers in the coaches, as he states the inquiry did in its calculations, because he points out that the natural inclination of people would be to sit on the leeward side of a (possibly draughty) coach. This could significantly affect the stability of the rolling stock, particularly that of the light second class coach. On the other hand even the inquiry at the time estimated that the bridge would require at least 33 lb/ft sq to endanger the structure. Furthermore Law points out that the rear two coaches were by far the most damaged when the train was salvaged. Thus, he argues, it was the train which then brought down the high girders. If this had not occurred, by pure chance, where the high girder work existed, then the train would simply have been blown off the bridge, and thus not brought the latter down. Law is of the view that whilst Bouch was not without some responsibility for the construction standard of the bridge he was unfairly scapegoated by the enquiry. This theory is not original and was put forward by Bouch in his defence. It was completely discredited at the official enquiry, and fails to address the question: if the train derailed and caused the bridge to fall, why was the bridge so weak? It also fails to explain why over half a mile of bridge was destroyed, and not just that part where the train derailed.

Only the locomotive (NBR 224) survived the disaster, being salvaged from the river and repaired at Cowlairs. It remained in service until 1919, acquiring the nickname of "The Diver"; many superstitious drivers were reluctant to take it over the newly rebuilt bridge.

Works of literature about the disaster

The Victorian poet William Topaz McGonagall commemorated this event in his poem The Tay Bridge Disaster. Likewise, German poet Theodor Fontane, shocked by the news, wrote his poem de:Die Brück’ am Tay (with obvious allusions to William Shakespeare and Friedrich von Schiller). It was published only ten days after the tragedy happened. Hatter's Castle, the 1931 novel of Scottish author A. J. Cronin, includes a scene involving the Tay Bridge Disaster, and the 1942 filmed version of the book dramatically recreates the bridge's catastrophic collapse. The bridge collapse figures prominently in Barbara Vine (Ruth Rendell's) 2002 novel The Blood Doctor. Scottish author Sorche nic Leodhas (collector/reteller of Scottish fairy tales and ghost stories) wrote a story The Tay Bridge Train (told as a true story before she wrote it down) (many people told stories to her father), about a man who survives because he is warned (by the ghost of his best friend) not to take the Tay Bridge train.

A second bridge

A new double-track bridge was designed by William Henry Barlow and built by William Arrol & Co. 60 ft (18 m) slightly upstream of, and parallel to, the original bridge. The bridge proposal was formally incorporated in July 1881 and the foundation stone laid on 6 July 1883. Construction involved 25,000 tons of iron and steel, 70,000 tons of concrete, ten million bricks (weighing 37,500 tons) and three million rivets. Fourteen men lost their lives during its construction, mostly due to drowning.

The second bridge opened on 13 July 1887 and remains in use. In 2003, a £20.85 million strengthening and refurbishment project on the bridge won the British Construction Industry Civil Engineering Award, in consideration of the staggering scale and logistics involved. More than 1,000 tonnes of bird droppings were scraped off the ironwork lattice of the bridge using hand tools, and bagged into 25 kg sacks. Hundreds of thousands of rivets were removed and replaced, all work being done in very exposed conditions, high over a firth with fast-running tides.

The stumps of the original bridge piers are still visible above the surface of the Tay even at high tide.

"Tay Bridge" was also the codename for the funeral plans for Queen Elizabeth, The Queen Mother.

See also

References

Notes

Bibliography

  • Charles Matthew Norrie, Bridging the Years: A Short History of British Civil Engineering, Edward Arnold (Publishers) Ltd., 1956.
  • John Prebble, The High Girders: The Story of the Tay Bridge Disaster, 1956 (published by Penguin Books in 1975) ISBN 0-14-004590-2.
  • John Thomas, The Tay Bridge Disaster: New Light on the 1879 Tragedy, David & Charles, 1972, ISBN 0-7153-5198-2.
  • David Swinfen, The Fall of the Tay Bridge, Mercat Press, 1998, ISBN 1-873644-34-5.
  • Peter R. Lewis, Beautiful Railway Bridge of the Silvery Tay: Reinvestigating the Tay Bridge Disaster of 1879, Tempus, 2004, ISBN 0-7524-3160-9.
  • Charles McKean Battle for the North: The Tay and Forth bridges and the 19th century railway wars Granta, 2006, ISBN 1-86207-852-1
  • John Rapley, Thomas Bouch : the builder of the Tay Bridge, Stroud : Tempus, 2006, ISBN 0-7524-3695-3
  • PR Lewis, Disaster on the Dee: Robert Stephenson's Nemesis of 1847, Tempus Publishing (2007) ISBN 978 0 7524 4266 2

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