Technical Advancements: The Cost of Progress

Technical Advancements: The Cost of Progress Transport by Land: Tay Bridge, 1879

Tay Bridge, 1879 Lesson Objectives: • Investigate the technological advancement in railway bridge construction • Realise that sometimes there is a heavy price to pay for advancements in technology and that lessons must be learnt

Tay Bridge, 1879 • Listen to this poem and write in the back of your books any important facts about the disaster.

Tay Bridge, 1879 Task: Listen to the poem and try and jot down important facts about the Tay Bridge Disaster, 1879. Note – When he says 90 lives were lost, it is now estimated to have been around 75.

Tay Bridge 1879 • In the 19th century, the people of Britain took pride in their technological achievements. • Britain’s railway system led the world. In 1879, the Victorian’s confidence in British technology was further boosted by the opening of a bridge across the River Tay in Scotland.

Tay Bridge 1879 • At 3km in length, it was the world’s longest bridge. • Queen Victoria herself travelled across the bridge • knighted its designer, Thomas Bouch, on the spot! 1822 - 1880

Tay Bridge 1879 • The Tay Bridge was a remarkable engineering achievement – or so it seemed.

Tay Bridge 1879 • The Tay Bridge disaster occurred during a violent storm on 28thDecember 1879 when the first Tay Rail Bridge collapsed while a train was passing over it from Wormit to Dundee. The train crashed into the river killing all aboard. • To this day, the Tay Bridge disaster remains the worst railway disaster in British history.

Tay Bridge 1879 Activity: • Watch the short documentary on the Tay Bridge disaster. • What do these images and documentary suggest about the horror of the tragedy? • http://www.youtube.com/watch?v=Zg4cG1CZHjI

So what happened? Train

Tay Bridge 1879 THEORY A Bill Dow – Theory A: Train “The rear carriages of the train derailed and ran into one of the cover plates. The force of this impact would shatter the cast iron lugs – leaving the bridge in a high wind without its proper structural support”. • The girder closest to Wormit, in the high girder section of the bridge, had bent during the lifetime of the bridge. The girder had been dropped during construction and bent. • It was straightened out and reused, but over time it returned to the bent shape. • As a result, the rail tracks that ran over it developed a kink. • This kink, combined with the high wind, may have been responsible for the train derailment.

So what happened? Wind Train

Tay Bridge 1879 THEORY B Tony Martin – Theory B: Wind “The disaster was investigated using modern computer analysis in conjunction with a modern approach to wind loading. The bridge was examined with and without the train to see what effect on the performance of the pier structure. And a pier was analysed under various load conditions with a view to proposing a mechanism for collapse of the navigation piers”. • The bridge was simply not strong enough to withstand the strength of the wind that night. • Although the presence of the train does affect structure, even without the train the bridge would have fallen that night.

So what happened? Wind Train Bridge Fatigue

Tay Bridge 1879 THEORY C Peter Lewis – Theory C: Bridge Fatigue “It was almost certainly the dynamic effects of the bridge itself well before the disaster that brought the bridge down. These led to gradual deterioration of the ironwork supporting the high girders”. • On the night of the storm, the bridge piers were no longer capable of supporting the load of the train. • Within that, fatigue and cracks in the bridge probably played an important role.

Tay Bridge 1879 Task: • Use the handout with the three possible theories for why the Tay Bridge collapsed. • You have to choose ONE theory from the three and write a short answer on why you agree with that theory. Also try and think about what you learnt from watching the documentary. • This activity forces you to make a decision and argue your point.

Task: Tay Bridge 1879 I think theory ____(A,B or C) is the correct theory to help explain why the Tay Bridge collapsed because___________(include a couple of reasons/ explanations to support your argument)

Tay Bridge 1879 So, why do you think the Tay Bridge collapsed? 8L vote

What Lessons Were Learnt? • All Bouch's bridges were examined and reinforced or rebuilt.

What Lessons Were Learnt? • Steel was approved by the Board of Trade for use in bridges. Designs using cast iron columns were barred.

What Lessons Were Learnt? • Regular and frequent inspections of bridges were made during and following construction by Board of Trade personnel.

What Lessons Were Learnt? • A new Tay Bridge was built adjacent and parallel to the original bridge reusing undamaged girders with some modifications. The new bridge is over twice the width to allow double rail tracks and greater lateral stability. Piers in the centre were built from wrought iron lattice work and steel. Original pier platforms were retained to act as breakwaters for the new bridge. New piers were tested by static loading for settlement. The building was started in 1881 and finished in 1885.

What Lessons Were Learnt? • A Royal Commission on "Wind Pressure on Railway Structures" was set up in 1881. Members of the Commission included W H Barlow, G Stokes and W Yolland. An extensive survey of wind speeds and pressures using anemometers was undertaken at numerous locations. Examples of overturned carriages by wind action were examined. A maximum wind pressure of 56 per square foot for design of bridges and rules for applying this specification to bridges of different construction were recommended.

Technical Advancements: The Cost of Progress