The Tay Bridge Disaster occurred on the 28th of December, the last Sabbath Day of 1879.
The Tay Bridge Disaster of 1879 remains one of Scotland’s most notorious events. As disasters go, it wasn’t that there was an unimaginable loss of life, but in an era when Victorian Britain prided itself on engineering magnificence, the collapse of the longest bridge in the world sent shock waves through the engineering profession. It was reported widely in the newspapers of the time and it is still the most famous of bridge disasters in the British Isles, “which will be remember’d for a very long time”. You can still see the foundations of the collapsed bridge as you cross the Tay on its replacement.
At 7:15 p.m. on the night of Sunday, the 28th of December, 1879, the central spans of the Tay Bridge, the entire high girders section, collapsed into the Firth of Tay at Dundee. Consequently and tragically, a northbound train, consisting of six carriages, plunged into the icy waters below. At the time, a gale, which was estimated at between storm force ten and eleven on the Beaufort Scale was blowing down the Tay estuary at right angles to the bridge. At St Fort, the last station before the Tay Bridge crossing, seventy-two passengers had been counted on board. Along with the train’s three crewmen, seventy-five souls is accepted as being the disaster’s final death toll.
Railway worker John Watt was an eyewitness who had been sheltering in a signalman’s hut when the train set out. He saw the light on the guard’s wagon “fall away” and bright flashes appear from what he took to be the front part of the train. He remarked to the signalman, “Either the girders or the train is down.” A more dramatic report was given by observers on the Dundee side: “Almost simultaneous with the entry of the train upon [the high girders section] of the bridge, a comet-like burst of fiery sparks sprang out…” to be followed by a streak of fire “In a long visible trail”, which was seen until “quenched in the stormy water below” and then, “there was absolute darkness on the bridge”. Rescue vessels were launched almost immediately, but the storm hampered all efforts to find anyone alive. In the end, only forty-six bodies were found as the tides had undoubtedly swept some corpses out into the North Sea.
The next day, ‘The Scotsman’ newspaper reported the disaster thus: “A catastrophe so appalling in its magnitude and suddenness as at first almost to baffle one’s efforts to realise it, occurred last night in the fall of a portion of the Tay Bridge, with, it is feared, a passenger train that had been in course of transit when the accident happened. It was pretty late in the evening when the intelligence reached Edinburgh, and up to an advanced hour only the most meagre information was here obtainable. Such as it was, however, the news received only tended to confirm the fears entertained when the fist vague intimation came to hand, that the fall of two or more girders of the bridge had involved lamentable loss of life.”
The bridge over the great estuary of the Tay had only been open for nineteen months, although it had been planned for many years. However, it was not until a November meeting of the North British Railway Company in1869, that a proposed design received approval. Thomas Bouch had already constructed several bridges and his experience was coupled with a reputation for building structures ‘on time and in full’. The foundation stone was laid on the 25th of July, 1871 and the bridge was duly opened for rail traffic on the 26th of September, 1877. The construction involved sinking piers into the riverbed, upon which was built a structure of cast iron columns, strengthened with wrought iron struts, girders and ties. The Tay Bridge, which carried a single rail track, was two miles long and had eighty-five spans between the piers, which rose to eighty-eight feet at the highest section above the river. As somewhat of a premonition, in hindsight, in February of 1877, a violent storm had blown up and two of the larger girders, each weighing two hundred tons, had been blown down. Astonishingly, by today’s standards, one of the damaged girders was recovered, repaired and replaced on the bridge.
The subsequent Court of Inquiry found that “The fall of the bridge was occasioned by the insufficiency of the cross bracing and its fastenings to sustain the force of the gale”. In other words, the bridge was not designed to withstand the strong winds. Two of the inquiry members were engineers and their findings differed from the chairman’s, however, several conclusions were agreed upon, namely, that “the design was basically faulty, the construction and materials were not of a high enough standard, the supervision of the bridge was unsatisfactory, train speeds over the bridge were too high and generally, safety had been ignored in favour of savings”. Thomas Bouch, by then Sir Thomas, was widely blamed for the tragedy and, whether from stress or guilt (Bouch’s own son-in-law had been on the train), his health began to fail and he died soon after, on the 30th of October, 1880.
To this day, there is still speculation about the cause and whether or not Thomas Bouch was to blame. There is the ‘blown down by the wind theory’ and the ‘train derailment theory’ and the ‘fatigue theory’. The latter theory has been ‘blown out of the water’ by two engineers, Tom Martin of MB Engineering Solutions, Motherwell, and Iain A. MacLeod of the University of Strathclyde, whose paper was published as recently as 2004. The idea of derailment is similar to the one proposed by Bouch at the inquiry, but fails to explain why the bridge failed in the manner that it did. Interestingly, computer-based structural analysis carried out by Martin and MacLeod points firmly at the wind being the root cause of the disaster. If you apply the principle of Occam’s razor to the problem as Martin and MacLeod have also suggested, the theory with the least amount of pre-suppositions and the simplest concepts is most likely the one with which to go. The strongest evidence points to the bridge being under designed for wind and it blew over due to inadequate bracing.
Let’s leave the last word to William McGonagall:
’Twas about seven o’clock at night,
And the wind it blew with all its might,
And the rain came pouring down,
And the dark clouds seem’d to frown,
And the Demon of the air seem’d to say-
“I’ll blow down the Bridge of Tay.”