Thursday, 4 February 2016

The Tay Bridge rail disaster, 1879

This is the story of the Tay Bridge disaster in December 1879 when a combination of factors, including extreme weather, caused part of the bridge to collapse just as a train was passing across it. There were no survivors.

The bridge to Dundee

Few, if any, rail accidents have lived as long in the collective memory as that of the Tay Bridge disaster of 28th December 1879. In part this is due to the absurd poem written soon after the event by Dundee poet William McGonagall, but that is by no means the whole story. The drama of the disaster, coupled with the fact that there were no survivors, was bound to make this a story that would grab the public’s attention and not let go, even down to the present day.

The railway line from Edinburgh to Aberdeen had two major problems during its construction, namely the Firths of Forth and Tay that interrupted the journey. Before these wide estuaries were bridged it was necessary for train passengers to disembark and take a boat journey across the water, which was clearly time-consuming and often uncomfortable. There was therefore a pressing need to build bridges.

The Tay Bridge was the first to be built, the designer being Thomas Bouch (1822-80). He had plenty of experience of railway design, including many bridges, but none of this length. However, this is hardly surprising given that no-one had ever tried to bridge such a distance before (the Firth of Tay is more than two miles wide at this point). Bouch was also awarded the contract to bridge the Firth of Forth, for which he designed a suspension bridge.

Given the relative shallowness of the Firth of Tay, Bouch planned to erect a series of brick pillars on which a single track lattice girder bridge would be built, each span being 200 feet wide. A particular requirement was that ships would have to be able to pass underneath the bridge at its central point, which meant that a gentle gradient would be needed from both sides to raise the tracks to the required height. The bridge would head straight across the Firth from Wormit on the southern shore, curving at the northern end to take the track into the station at Dundee having joined the line that ran along the north shore from Perth.

Bouch’s first problem was that he discovered, having started to build the brick piers and completed 14 of them, that the bed of the Tay was not as solid as first thought. In order to reduce the load he decided to build the remaining piers in cast iron rather than brick. He also increased the spans from 200 feet to 245 feet.

The section intended for shipping to pass underneath was designed somewhat differently. Whereas the lattice girders for the rest of the bridge had the rails laid on top, the “high girders” section had the rails running inside the girder cage, thus allowing clearance underneath of 88 feet.

The bridge was completed in 1878 and inspected and tested by Major-General Hutchinson from the Board of Trade. In one test, six locomotives, weighing an average of 73 tons, were coupled together to run across the bridge at 40 miles an hour. The Inspector passed the bridge as safe, but stipulated a speed limit of 25 miles an hour. He also expressed regret that he had not been able to test the bridge under high wind conditions, which proved to be a fateful comment.

The bridge was hailed as a masterpiece of British engineering, and it was opened to great acclaim on 1st June 1878. A year later Queen Victoria crossed the bridge on her way to Balmoral and awarded a knighthood to Thomas Bouch.

The Tay Bridge disaster

However, disaster was to strike late the following year. On Sunday 28th December 1879 a gale was blowing as the passengers on the afternoon service from Edinburgh to Dundee crossed the Firth of Forth by ferry to join the train that would take them the rest of the way. It was headed by a much larger and more powerful locomotive than was usual on this service, namely a 4-4-0 express locomotive that had been built only eight years before. The small tank locomotive that usually pulled the train had broken down and was replaced by the spare engine from Dundee. Having had such an uncomfortable crossing the passengers would have welcomed the prospect of a fast and steady journey for the rest of the way.

The last stop before the Tay crossing was at St Fort, where the passengers’ tickets were collected. Because the bridge had only a single track, a system was used by which the driver was handed a metal token which would then be collected on the other side. After the St Fort signalman, named Barclay, had handed the token to Driver Mitchell the wind was so strong that he could not stand upright and had to crawl on all fours back to his signal-box.

Barclay and another railwayman named Watt watched the train as it made its way across the bridge. They did this because an earlier train had been seen to emit sparks from its wheels as it crossed and they wanted to see if this one did the same. Barclay had just seen sparks from the Edinburgh train, and was about to mention this to Watt, when a sudden and extremely violent gust of wind shook the signal-box. They both saw a flash of light from the bridge and then nothing else. Barclay tested the instruments that connected him with the north shore but got no response. When a break in the clouds allowed the moon to show them the bridge, they saw that the high girders were missing.

On the north shore a man with a telescope reported to the station staff that the high girders were down. A sailor on a ship in the Firth had been knocked down by the sudden gust and saw the hole in the bridge when he looked up.

At first, the watchers on the south side hoped that the train had cleared the high girders before they collapsed, while those on the north side hoped that it had stopped in time and reversed back to St Fort. However, it soon became clear that the train had gone with the bridge and all the passengers and crew were dead. It was not easy at first to work out how many had been lost but the final total was put at 75.

Whose fault?

The enquiry that followed was not slow to assign most of the blame to faulty design by Sir Thomas Bouch. In particular, the use of cast iron for the vital bracing ties that linked the main wrought iron members of the bridge columns was criticised as being inadequate, especially as cast iron can become brittle when exposed to extreme conditions. It was also pointed out that the total weight of the bracing ties, at only 400 tons, was nothing like enough to secure a bridge that weighed more than 10,500 tons.

Sir Thomas suddenly went from hero to zero. He was condemned from all sides and sacked from his job on the Forth Bridge, which was later built to a completely different design. His health soon failed and he died in October 1880 at the age of 58.

However, there were factors other than poor design that contributed to the collapse. One was poor workmanship at the factory that forged the iron components, many of which were found to be sub-standard. Another was poor maintenance, in that many of the ties had worked loose and had not been re-tightened properly. Also, the speed limit of 25 miles an hour was regularly ignored by drivers, especially as trains ran down the slope into Dundee. It would appear that Sir Thomas was made the scapegoat for all the poor work that led to the tragedy.

One factor that had not been accounted for by anyone was the extreme weather on that particular night. Severe gales are not uncommon on the east coast of Scotland, but this one was particularly bad, and the final gust would appear to have been exceptional, possibly of hurricane force. Had a train not been on the bridge at the time it may well have survived, as might the train had it crossed a few minutes earlier or later.

The sole survivor of the disaster was the locomotive that was later raised from the bed of the Tay and repaired. It continued to run until 1919, and even pulled trains across the new Tay Bridge, although it was not until 1908 that any driver was prepared to take it across, for fear of tempting fate.

The new bridge, completed in 1887 and still in use, was built to a much more sturdy design, being double track and with brick pillars all the way across. The new bridge used the stumps of the old bridge’s piers as breakwaters, and these are all that can be seen today to remind one of the tragedy of 28th December 1879.

© John Welford