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Tay Rail Bridge

2007 Schools Wikipedia Selection. Related subjects: Railway transport

   Original Tay Bridge (from the South)
   Enlarge
   Original Tay Bridge (from the South)

   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 closeup of the central section of the second Tay Bridge
   Enlarge
   A closeup of the central section of the second Tay 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.
   The full length of the second Tay Bridge
   Enlarge
   The full length of the second Tay Bridge
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