Bridge oscillations

Testimony was taken from the many workers employed during construction and painting of the structure just after completion. Their evidence was more compelling, especially from painters working at the top of the high girders piers during passage of trains, as well as during windy weather. They were painting the cast iron of the piers during the summer of 1879. In the main, they reported feeling strong sideways as well as vertical motion:

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5.2 Eye-witness testimony

Their first main aim was to question local witnesses, including several who claimed to have seen the fall itself. One especially impressive eye witness was Alexander Maxwell, who lived on Magdalen Green, near the north end of the bridge. He was examined by Mr Trayner, counsel for the enquiry:

942. You are an engineer? – Yes

943. You live with your father, who is an ex-baillie of this town at Magdalen Green,
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5.1 Overview

The enquiry team set up by the Board of Trade, and sitting in Dundee Court House, held an initial session lasting several days starting on Saturday 3 January 1880. There were three members chaired by Mr Rothery, Commissioner of Wrecks. The others were Colonel Yolland, the Inspector of Railways, and Mr W H Barlow, president of the Institute of Civil Engineers, and a distinguished practising civil engineer.

Henry Rothery was a mathematics graduate but trained as a barrister. He had been a
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4.11 Model for pier failure

Figure 39 shows a simple model to explain the failure of the piers. The lateral wind loading on the top of the pier bends to shear the pier from a rectangle into a parallelogram. In turn, this stretches the tie bars and also strains the bolted joints at the top and bottom of each column.

Figure 39
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4.10 High girders and the train

Divers found the high girders lying on their sides in the shallow water of the river bed a short distance away (Figure 22), within which the almost intact remains of the train itself was found. No bodies were recovered because they had all been washed away by the river or tide. Although bodies were recovered in the months that followed, some 29 victims were never found.

Most of the train was lying inside the fifth span
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4.9 Survey results

We have inspected some of the remains of the collapsed bridge using the set of photographs taken shortly after the disaster for the official inquiry. It is important to emphasise that the pictures form only a small part of the total of fifty, but those chosen were selected to give the clearest evidence of the failure modes in the cast-iron piers that supported the high girders. They are by the far the best real evidence to rely on to understand how and why the structure failed.

It would
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4.8 Photographs showing the detail: standing pier 28

The final part of the survey deals with the two standing piers connected to the lower girders left after the high girders section fell during the disaster. The whole of pier 28 is shown in Figure 34, and two close-ups of the columns are shown in Figures 35 and 36.

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4.7 Photographs showing the detail: damage to pier 1

The final example of a partly collapsed pier is pier 1, photographed from the base of pier 28 and shown in Figure 32. Fracture damage to the flange at the top of the second tier is visible on the east-most column (top right); a large chunk of metal has broken off. The southern column (right of centre) exhibits a matching fracture where the parts are still held in position by the wrought iron strut. Propagation of the same cr
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4.6 Photographs showing the detail: debris field

The relatively clear platform of pier 3 is also visible in Figure 28. There are several pieces of shaped metal on the floor, at least one appears to be a bolt. A close-up of the floor, taken looking east, is shown in Figure 31. So, what are the fragments? At least three bolts are visible, but more significantly, there are nine broken lug ends. These are the
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4.5 Photographs showing the detail: broken lugs

The bases of the columns to which they were attached originally on pier 3 deserve closer inspection. Even at this scale, the two fractured lugs where the tie bars were formerly fixed are clearly visible at the right-hand and left-hand sides of Figure 28 (arrowed). The southern (left-hand) column base in Figure 28 is shown at about ×8 magnification in F
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4.4 Photographs showing the detail: partly collapsed piers

There were only two piers that showed tiers still standing, piers 1 and 3, next to the south pier still standing (pier 28). They are important because the debris lying on the platforms is much reduced, giving clear views of the platform surface and the state of damage of the upstanding tiers.

Two views are shown of pier 3, a view from pier 2 (Figure 27), and a close-up of the lowest tier looking west (Author(s): No creator set

4.3 Photographs showing the detail: collapsed piers

Figures 23 and 24 present the east- and west-facing views of a collapsed pier, pier 5, which lay just ahead of the train before it was lost in the disaster. Figure 23 shows parts of two tiers of what was presumably the lowest part of the cast-iron pier on this platform. The columns point towards the east, indicating the lowest tiers fell in this direction d
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4.2 An introduction to the Board of Trade photographs

It is important to bear in mind that these shots show the bridge remains in the state they were in just after the accident, and are almost exactly what the investigators would have seen when they inspected the bridge (see Input 8, linked below).

Click 'View document' below to open Input 8

The weather cleared after the storm, and the piers were examined in bright sunshine. The photographer to
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4.1 Condition of the bridge: an overview

An investigation was put into motion by the Board of Trade (BoT) as soon as news of the catastrophe reached London. Three commissioners were appointed to consider the evidence. They proceeded at their task with haste, knowing the country looked to them for an explanation of the accident.

Fifty photographs were taken of the remains of the bridge about a week after the collapse at the request of the BoT enquiry team.

The photographs are vital evidence of the way the bridge piers fai
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Disaster!

The train receded into the darkness and the light of the three red tail lamps grew dimmer. Sparks flew from the wheels and merged into a continuous sheet that was dragged to the lee of the bridge parapet. Eyewitnesses would later recall at the inquiry that they saw a bright glow of light from the direction of the train just after it must have passed into the high girders section, and then all went dark.

The train was timed to pass the Dundee signal box at 7.19 pm. When it failed to arri
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3.5 Sunday 28 December 1879

The morning of Sunday 28 December 1879 was quiet. When Captain Wright took his ferry boat, the Dundee, across the firth at 1.15 pm, he noted that the weather was good and the water was calm. The 4.15 pm crossing was just as uneventful, but the captain noted that the wind had freshened.

By 5.15 pm a gale was moving in from the west and the river, in the words of the captain ‘was getting up very fast’. The local shuttle train left Newport at 5.50 pm and arrived at Dundee s
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3.4 Building the bridge

The contract for the bridge was won by the firm of Charles de Bergue, and a contract signed on 8 May 1871, whereby the contractor undertook to have the bridge ready for traffic in three years at a price of £217 000. In the event the bridge was opened on 31 May 1878, by which time it had cost £300 000.

Work started on the south bank of the Tay, with piers laid on to solid rock foundations. As the piers advanced into the estuary, foundations needed to be sunk onto the river bed,
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Construction of piers

The dimensions and detailed construction of the cast-iron piers are shown in Figure 15. A single pier consisted of six columns of cast iron tied together by struts, bars and rods made from wrought iron. Each pier in the high girders section was built up by bolting together seven flanged cast-iron columns, giving seven tiers. The ends of the flanges were fastened together with eight 1.125 inch (1⅛) wrought iron bolts
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Bridge girders

Figures 11 and 12, below, are photographs of the bridge taken from the south and north banks of the firth.

The girders of the bridge were supported on a total of 85 piers. The first 14 piers were made from brick and masonry, built up as a solid structure. The rest were fabricated from iron on masonry platforms, and by comparison, appeared rather insubstantial (Figure 11). Over most of the bridge, the track ran on top
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3.3 Description of the bridge

An outline plan of the bridge shows the main piers on which the bridge was laid (Figure 10). To allow shipping to pass up the Tay to Perth, a height of about 88 feet was required between the bridge girders and the high water mark in the middle of the firth. On the south bank, at Wormit, the land rose steeply to a height of about 200 feet, and this proved ideal as a jumping-off point for the bridge.

After leaving the ba
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