Tay Rail Bridge
2007 Schools Wikipedia Selection. Related subjects: Railway transport
The Tay Rail Bridge (originally the Tay 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 ( grid reference NO391277).
As with the Forth (Rail) Bridge, the Tay Bridge's more common name, the Tay Rail Bridge, has arisen in the years since the construction of a road bridge over the firth, the Tay Road Bridge.
The first Tay Bridge
The original Tay Bridge was constructed in the 19th century 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 structure was not as heavily loaded as a railway bridge, such as the Dee bridge which fell in 1847 due to poor use of cast iron girders. Later, Gustave Eiffel would use the same design to create several large viaducts in the Massif Central (1867).
Several proposals for constructing a bridge across River Tay date back to at least 1854. The North British Railway (Tay Bridge) Act was incorporated on July 15, 1870 and the foundation stone was laid on July 22 of the following year. The first engine to cross the bridge was on September 22, 1877 and upon its completion in early 1878, the Tay bridge was among the longest in the world. The bridge was officially opened by Queen Victoria on June 1, 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 which was running over its single track. More than seventy-five lives were lost, including Sir Thomas' son-in-law. (A common urban myth in Dundee is that Karl Marx would have been a passenger on the train had illness not prevented him from travelling on that date.)
Investigators quickly determined that the cylindrical cast iron columns supporting the thirteen longest spans of the bridge (each 245 ft (75 m) in length) were of poor quality. In particular, the lugs used to attach the wrought iron bracing bars were moulded with the columns, introducing a fatal weakness. It was these lugs which failed first in the accident, and so destabilised the entire centre part of the bridge. No allowance for wind load had been made by Bouch; such calculations were not common practice until precipitated by the disaster. However, the High Girders section in the middle of the bridge was top heavy, making this part insecure. It was this section that wholly collapsed into the Tay during the accident.
Official inquiry
The official inquiry was chaired by Henry Cadogan Rothery, Commissioner of Wrecks, supported by Colonel Yolland (Inspector of Railways) and the 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 many 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 towers. Noble did not attempt to re-tighten the joints, but instead hammered shims of iron between them in an attempt to stop the rattling. The enquiry demolished 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 problem continued up till the final collapse of the High Girders. It indicated that the centre section was unstable to lateral movement, movement that had been 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 they were ignored by the bridge's owners, the North British Railway. Some distinguished passengers, such as the Provost of Dundee, had timed trains moving across the bridge and found they were travelling at about 40 mph, well in excess of the official limit of 25 mph.
The Board of Trade, concerned about Bouch's design for the planned Forth 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 using designs by Benjamin Baker and John Fowler. Bouch died within a year of the disaster.
Only the locomotive (NBR #224) survived the disaster, being salvaged from the river and repaired at Cowlairs. Subsequently, the engine remained in service until 1919.
Verses inspired by the disaster
The Victorian poet William Topaz McGonagall commemorated this event in his famous (perhaps infamous) poem The Tay Bridge Disaster. Likewise, German poet Theodor Fontane, shocked by the news, wrote his poem Die Brück' am Tay (with obvious allusions to William Shakespeare and Friedrich von Schiller). It was published only ten days after the tragedy had happened.
A second bridge
A new double-track railway bridge was designed by William Henry Barlow and built by William Arrol 60 ft (18 m) upstream of, and parallel to, the original bridge. The bridge proposal was formally incorporated in July 1881 and the foundation stone laid on July 6, 1883. Construction involved twenty-five thousand tons of iron and steel, seventy thousand tons of concrete, ten million bricks (weighing thirty-seven and a half thousand tons) and three million rivets. Fourteen men lost their lives during its construction, mostly due to drowning.
The second bridge was opened on 13 July 1887 and remains in use today. 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 one thousand tonnes of bird droppings were scraped off the ironwork lattice of the bridge using hand tools and bagged into 25 kg sacks; and hundreds of thousands of rivets were removed and replaced, all 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 at low tide.
