Tay Bridge disaster

The Tay Bridge disaster occurred during a violent European windstorm on Sunday 28 December 1879, when the first Tay Rail Bridge collapsed as a North British Railway passenger train on the Edinburgh to Aberdeen Line travelling from Burntisland to Dundee passed over it, killing all aboard. The bridge, designed by Sir Thomas Bouch, used lattice girders supported by iron piers, with cast iron columns and wrought iron cross-bracing. The piers were narrower and their cross-bracing was less extensive and robust than on previous similar designs by Bouch.
Bouch had sought expert advice on wind loading when designing a proposed rail bridge over the Firth of Forth; as a result of that advice he had made no explicit allowance for wind loading in the design of the Tay Bridge. There were other flaws in detailed design, in maintenance, and in quality control of castings, all of which were, at least in part, Bouch's responsibility.
Bouch died less than a year after the disaster, his reputation ruined. Future British bridge designs had to allow for wind loadings of up to. Bouch's design for the Forth Bridge was not used.
As of 2024, it remains the fifth-deadliest railway accident in the history of the United Kingdom, as well as the second deadliest rail accident in Scottish history, being surpassed by the UK's deadliest: the Quintinshill rail disaster.

Bridge

Construction of the original Tay Rail Bridge began in 1871. In its initial design, the bridge was to be supported by brick piers resting on bedrock. Trial borings had shown the bedrock to lie at no great depth under the river. At either end of the bridge, the bridge girders were deck trusses, the tops of which were level with the pier tops, with the single-track railway running on top. However, in the centre section of the bridge the bridge girders ran as through trusses above the pier tops in order to give the required clearance to allow passage of sailing ships to Perth.
The bedrock lay much deeper than the trial borings had shown, and the bridge's designer, Sir Thomas Bouch, redesigned the span with fewer piers and correspondingly longer girders. The pier foundations were now constructed by sinking brick-lined wrought iron caissons onto the riverbed, and filling these with concrete. To reduce the weight these had to support, Bouch used open-lattice iron skeleton piers; each pier had multiple cast-iron columns taking the weight of the bridging girders. Wrought iron horizontal braces and diagonal tiebars linked the columns in each pier to provide rigidity and stability.
The basic concept was well known, but for the Tay Rail Bridge, the pier dimensions were constrained by the caisson. For the higher portion of the bridge, there were thirteen girder spans. In order to accommodate thermal expansion, at only three of their fourteen piers was there a fixed connection from the pier to the girders. There were therefore three divisions of linked high girder spans, the spans in each division being structurally connected to each other, but not to neighbouring spans in other divisions. The southern and central divisions were nearly level, but the northern division descended towards Dundee at gradients of up to 1 in 73.
The bridge was built by Hopkin Gilkes and Company, a Middlesbrough company which had worked previously with Bouch on iron viaducts. Gilkes, having first intended to produce all ironwork on Teesside, used a foundry at Wormit to produce the cast iron components, and to carry out limited post-casting machining. Gilkes were in some financial difficulty; they ceased trading in 1880, but had begun liquidation in May 1879, before the disaster. Bouch's brother had been a director of Gilkes, and all three had been colleagues on the Stockton and Darlington thirty years previously; on Edgar Gilkes's death in January 1876, Bouch had inherited shares valued at £35,000, but also owed for a guarantee of £100,000 of Gilkes borrowings and had been unable to extricate himself.
The change in design increased cost and necessitated delay, intensified after two of the high girders fell when being lifted into place in February 1877. The first engine crossed the bridge seven months later. A Board of Trade inspection was conducted over three days of good weather in February 1878; the bridge was passed for use by passenger traffic, subject to a speed limit. The inspection report noted:

When again visiting the spot I should wish, if possible, to have an opportunity of observing the effects of high wind when a train of carriages is running over the bridge.

The bridge was opened for passenger services on 1 June 1878. Bouch was knighted in June 1879 soon after Queen Victoria had used the bridge.

Disaster

On the evening of Sunday 28 December 1879, a violent storm was blowing virtually at right angles to the bridge. Witnesses said the storm was as bad as any they had seen in the 20–30 years they had lived in the area; one called it a 'hurricane', as bad as a typhoon he had experienced in the China Sea. The wind speed was measured at Glasgow – – and Aberdeen, but not at Dundee.
Higher windspeeds were recorded over shorter intervals, but at the inquiry an expert witness warned of their unreliability and declined to estimate conditions at Dundee from readings taken elsewhere. One modern interpretation of available information suggests winds were gusting to.
Use of the Tay Rail Bridge was restricted to one train at a time by a signalling block system using a baton as a token. At 7:13 p.m. a North British Railway passenger train from Burntisland slowed to pick up the baton from the signal cabin at the south end of the bridge, then headed out onto the bridge, picking up speed.
The signalman turned away to log this and then tended a stove, but a friend present in the signal cabin watched the train: when it got about from the cabin he saw sparks flying from the wheels on the east side. He had also seen this on the previous train. During the inquiry, testimony was heard that the wind was pushing the wheel flanges into contact with the running rail. John Black, a passenger on the previous train that crossed the bridge, explained that the guard rails protecting against derailment were slightly higher than and inboard of the running rails. This arrangement would catch the good wheel where derailment was by disintegration of a wheel, which was a real risk before steel wheels, and had occurred in the Shipton-on-Cherwell train crash on Christmas Eve 1874.
The sparks continued for no more than three minutes, by which time the train was in the high girders. At that point "there was a sudden bright flash of light, and in an instant there was total darkness, the tail lamps of the train, the sparks and the flash of light all... disappearing at the same instant." The signalman saw none of this and did not believe it when told. When the train failed to appear on the line off the bridge into Dundee he tried to talk to the signal cabin at the north end of the bridge, but found that all communication with it had been lost.
Not only was the train in the river, but so were the high girders and much of the ironwork of their supporting piers. Divers exploring the wreckage later found the train still within the girders, with the engine in the fifth span of the southern 5-span division. There were no survivors; only 46 bodies were recovered out of 59 known victims. Fifty-six tickets for Dundee had been collected from passengers on the train before crossing the bridge; allowing for season ticket holders, tickets for other destinations, and for railway employees, 74 or 75 people were believed to have been on the train. It has been suggested that there were no unknown victims and that the higher figure of 75 arises from double-counting in an early newspaper report in the Dundee Courier, but the inquiry did not take its casualty figures from the press; it took sworn evidence and did its own sums.

Court of inquiry

Evidence

A court of inquiry was immediately set up: Henry Cadogan Rothery, Commissioner of Wrecks, presided; supported by Inspector of Railways William Yolland and William Henry Barlow, President of the Institution of Civil Engineers. By 3 January 1880, they were taking evidence in Dundee; they then appointed Henry Law, a qualified civil engineer, to undertake detailed investigations. Whilst awaiting his report they held further hearings in Dundee ; having got it they sat at Westminster to consider the engineering aspects of the collapse.
By then the railway, the bridge's contractor and Bouch had separate legal representation, and the NBR had sought independent advice from James Brunlees and John Cochrane, both engineers with extensive experience of major cast iron structures. The terms of reference did not specify the underlying purpose of the inquiry – to prevent a repetition, to allocate blame, to apportion liability or culpability, or to establish what precisely had happened. This led to difficulties during the Westminster sessions. When the court reported their findings at the end of June, there was both an Inquiry Report signed by Barlow and Yolland and a minority report by Rothery.

Other eyewitnesses

Two witnesses, viewing the high girders from the north almost end-on, had seen the lights of the train as far as the 3rd–4th high girder, when they disappeared; this was followed by three flashes from the high girders north of the train. One witness said these advanced to the north end of the high girders with about fifteen seconds between first and last; the other that they were all at the north end, with less time between. A third witness had seen "a mass of fire fall from the bridge" at the north end of the high girders. A fourth said he had seen a girder fall into the river at the north end of the high girders, then a light had briefly appeared in the southern high girders, disappearing when another girder fell; he made no mention of fire or flashes.
'Ex-Provost' Robertson had a good view of most of the bridge from his house in Newport-on-Tay, but other buildings blocked his view of the southern high girders. He had seen the train move onto the bridge; then in the northern high girders, before the train could have reached them, he saw "two columns of spray illuminated with the light, first one flash and then another" and could no longer see the lights on the bridge; the only inference he could draw was that the lit columns of spray – slanting from north to south at about 75 degrees – were areas of spray lit up by the bridge lights as it turned over.