Tay Bridge disaster



A contemporary illustration

Details
Date: 28 December 1879; 19:16
Location: Dundee, Scotland
Line: Edinburgh to Aberdeen Line
Operator: North British Railway
Incident type: Bridge collapse
Cause: Structural failure

Statistics
Trains: 1
Passengers: 59
Deaths: 75 estimate, 60 known dead

The Tay Bridge Disaster occurred during a violent storm on Sunday 28 December 1879, when the first Tay Rail Bridge collapsed as a train 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 56 pounds per square foot (2.7 kilopascals). Bouch's design for the Forth Bridge was not used.

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Bridge



Original Tay Bridge from the north

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 "high girders" ) the bridge girders ran as through trusses above the pier tops (with the railway inside them) in order to give the required clearance to allow passage of sailing ships to Perth.

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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 (10 to 11 on the Beaufort scale) 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;[8][9] one called it a 'hurricane', as bad as a typhoon he had experienced in the China Sea. The wind speed was measured at Glasgow – 71 mph (114 km/h; 32 m/s) (averaged over an hour) – 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 80 mph (129 km/h; 36 m/s).

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 (NBR) passenger train from Burntisland (consisting of a 4-4-0 locomotive, its tender, five passenger carriages, and a luggage van) 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.



A photograph of the bridge, showing four rails; the inner two guard rails are unpolished.

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 200 yards (180 m) 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.

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