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Beautiful Railway Bridge of the Silvery Tay

Reinvestigating the Tay Bridge Disaster of 1879

The History Press

An Introduction

The railways of Britain have long held a particular fascination for the public, perhaps because they were first developed here and so led the world into a new age of fast communications. It has left a rich heritage of buildings and engineered structures that have inspired artists, film directors and writers, both at the time of their construction and with the passage of time. Turner's mysterious picture, 'Rain, Steam and Speed', painted around 1844, celebrated the longest brick arch ever built in a bridge on the Great Western Railway as it crossed the Thames at Maidenhead.

Railway accidents were instrumental in shaping the national consciousness, such as the harrowing experience of Charles Dickens in the Staplehurst disaster of 9 June 1865. A boat train was derailed and fell through a small bridge made from cast-iron girders because the rail had been removed by platelayers, and not replaced in time. Dickens was travelling in the only coach to survive intact, and gave comfort to dying and injured passengers. The trauma led him to write a ghost story, The Signalman, the following year. It was dramatised in the 1970s by the BBC, starring Denham Eliot in the main role, and follows the original story very closely. It includes a terrifying crash in a tunnel (possibly based on the Clayton tunnel crash of 1861, which killed 23 and injured 176 passengers), presaged by a phantom under the red warning lamp at the entrance to the tunnel. The phantom warns the railwayman of his own demise, which he fails to recognise in time. According to L.T.C. Rolt, the after-effects of the Staplehurst crash contributed to Dickens' early death at the age of fifty-eight in 1870.

At a later time, the railway network became deeply embedded in the British consciousness, with the release of Nightmail by the GPO film unit (1936) and the Forth Bridge sequence in Hitchcock's The Thirty-Nine Steps (1937). Brief Encounter (David Lean, 1945) was set almost entirely in a railway station and, albeit incidentally, gave the steam train a romantic aura. The railway age was initially pioneered by great Victorian railway engineers and entrepreneurs such as Telford, Brunel and the Stephensons, father and son. Engineers such as W.H. Barlow and his son, who built the new Tay Bridge, and John Fowler and Benjamin Baker, the builders of the Forth Railway Bridge, were pioneers of the later efforts to complete the system to cover all of the United Kingdom.

There is, however, another side to those great successes: the many accidents which occurred on the early railway system, both of individuals and groups of passengers killed or injured by unsuspected events with the new technology of the era. As events unfolded, many new and quite unsuspected problems occurred, although some were entirely predictable.

The First Fatality

The very first accident occurred on the opening day of the first passenger rail service on the Manchester–Liverpool line in 1830. The victim was William Huskisson, the local MP and a vocal proponent of the new railway. He was injured by The Rocket while attempting to enter the compartment of a carriage, and died a few hours later. Such an eminent victim attracted great attention to the problem of public safety with the new machines, and further vitriol from their powerful opponents, the canal owners. While the accident might have been misadventure, it also gave the first indication of the problem of large machines moving at speed on a fixed track with poor means of braking.

But when all the glitches had been ironed out from this first railway line, it achieved almost notorious success in fast passenger transportation between Liverpool and Manchester, two pre-eminent cities of the Industrial Revolution. That success fuelled further growth, especially in trade carried along the new line. It was to have great significance for development of an expanding network, often at the hands of entrepreneurs like George Hudson, who exploited public enthusiasm for the technology. It led to railway mania, which was at its height in the subsequent decade, the 1840s. As the system grew to cover much of England, the potential for accidents grew too. Not dissimilar events were occurring in France, never far behind Britain in the development of the new technology.

The Tragedy at Versailles

The first ever major rail disaster occurred when a passenger train travelled from Paris to Versailles in 1842. The train involved had been scheduled to carry visitors to the great palace outside Paris to celebrate the birthday of the king, Louis Philippe, an event which featured a display of the famous fountains in the equally celebrated gardens. The return train (drawn by two locomotives and tightly packed) left Versailles at about 5.30 . on 8 May. When travelling at speed between Bellevue and Meudon, an axle on the front locomotive fractured, and the body of the engine fell onto the track. The second locomotive ran into the remains, and the ensuing pile-up of the carriages caused great loss of life, mainly because the carriages were ignited by hot embers from the wrecked fire boxes of the locomotives.

According to one commentator writing in 1879, fifty-two or fifty-three passengers lost their lives and forty were injured, although the exact number of deaths remained uncertain since so many bodies were totally consumed by the fire. One reason for the large casualty list was the practice of locking carriage doors to prevent passengers leaving the train while in motion. The early carriages were also rather flimsy and were mainly built from wood, so encouraging the subsequent fire. Bodies were burned beyond recognition. One distinguished victim was Admiral D'Urville, who was identified in an investigation by the Academy of Sciences. They employed a sculptor, who was able to recognise his skull from a cast he had recently made.

At the time the cause seemed obvious enough, and a number of investigations probed more deeply into the reason for the fractured shaft. However, none appeared to have discovered the root cause of the axle failure. Modern re-evaluation indicates that the broken shaft probably failed by fatigue from a sharp corner machined into the axle. Sharp corners in highly stressed components concentrate the applied stress, so that it can be many times the applied load. The material cannot withstand the high stress, so a crack forms at the corner and slowly grows with every application of stress. Every time the shaft was driven, the crack grew slowly until it reached a size when the solid iron could no longer support the load, and it suddenly failed catastrophically. Some early Victorian engineers, such as Rankine and Braithwaite, became aware of the problem, but their pioneering observations were not followed up by others. Fred Braithwaite pointed to a wide variety of products, such as cast-iron girders and steam engine beams as well as wrought-iron axles, which had failed suddenly and mysteriously. It was not until later (in the 1860s) that systematic research in Germany explored the problem of railway wheels and axles in greater detail. The solution was very simple: remove the sharp corners in a shaft by rounding it out. Such failures of shafts and wheels were to create many more accidents before their causes were correctly identified and remedial action taken by designers. But fatigue is a problem with us still, and has caused many disasters of recent times, such as those of the Comet aircraft and the Hatfield crash, when an express derailed at high speed in 2000.

The Fall of the Dee Bridge

Bridge failures could be almost as catastrophic, the first such major accident being on a bridge recently erected by Robert Stephenson on the new Chester–Holyhead section of the railway. This part was the final section of the London–Holyhead railway, crossing the country from south to north-west, and had been conceived nine years before in 1838. It would require many bridges, not least one across the Menai Straits itself. While it would be several years before completion of the massive Britannia Bridge, other bridges on the line were finished for local traffic, including a bridge across the tidal Dee River at Chester. Following Parliamentary approval by an Act of 1845, large cast-iron girders were laid on piers across the river near the city of Chester. It was completed by the end of 1846, and inspected and approved for traffic shortly afterwards.

Less than a year later, disaster struck on 24 May 1847. While a passenger train had almost crossed to the far side, one of the cast-iron girders suddenly fractured near the centre of the third or final span. The locomotive gained the far side but the tender and the carriages crashed about 30ft into the shallow river below (1.1). The locomotive actually reached the far bank of the river, but the tender derailed and struck the abutment, causing some damage to the masonry.

The driver of the locomotive stopped as soon as he realised what had happened but, seeing he could do little at the scene, drove off at speed to raise help. After giving the alarm at the nearby station, Saltney Junction, he changed over to the opposite line and re-crossed the intact side of the bridge to stop oncoming trains. Such action required no little courage, given the earlier collapse! Although only five passengers died, and sixteen were injured, the accident created a furore among the public. They wanted to know why such a new bridge could fail so suddenly.

The subsequent Inquest provided the details of the design of the bridge, its specification and events leading up to the failure. Eyewitness statements described the sequence of events very precisely. Detailed reports were provided by numerous experts, including a thorough account by Captain Simmons of the newly appointed Railway Inspectorate. Robert Stephenson, the designer and builder, came under attack, but was advised to raise the defence that the locomotive had derailed, hit the bridge and caused the girder to fail. So what really happened that day?

Eyewitnesses

It was fortunate that the day was clear and that there were many people close to the bridge when it failed. The fall had actually been seen by several witnesses. Thomas Jones, a publican and milkman, was on the Grosvenor Bridge 700 yards away, and he described what he saw as the train crossed over:

I saw the train at the ship yard; I put my milk cans down and watched it across the middle of the bridge; when the train got on the furthest arch on the Saltney side, I observed a crack open in the middle of the girder; the engine and tender were about the centre; the crack opened from the bottom; the engine had passed the crack, and the tender was right upon it; the engine and tender went on, and I saw the tender give a rise up; the carriages gave a jump and fell backward; the last carriage went down first according to my judgment; the next [thing] I saw was the large stones fall off the wall on the Saltney side; I heard a crash when they fell; I am certain the girder opened from the bottom; all went smooth before the tender jumped, and went against the corner of the abutment; the bridge was broke before the tender jumped; I think the jump of the tender broke the coupling of the carriages.

Many witnesses were so close that they were on the scene very quickly, as were many other local residents who had heard the crash and rushed to assist. Their assistance to the injured undoubtedly saved many lives, given that the carriages were part submerged in the cold river below the bridge (1.1).

The Painters

The prior and short history of the bridge, and especially its behaviour under load, was described by a number of painters who had been employed on the bridge just before the accident. Indeed, they gave evidence first at the Inquest. William Clegg described the deflection of the girders under load:

I have painted the girders on the new bridge in April and May last; they had been painted before that; I observed no peculiarity of the joints where the trusses fastened the girder; I was on the bridge when the ballast train passed over it; I observed a deflection of the girder from 1½ inches to 2in on both lines; I observed it also when the passenger trains went over; they went faster than the ballast trains considerably; the extent of the deflection was 3½ inches to 4in; I got my rule and put it under the girder and noticed how much it went down ...

The bridge had originally been designed with shorter spans across the river, but the number of piers had been reduced at the direction of others. When in operation and loaded, large deflections had been observed by the painters working on the girders at the time. The failure, based on the evidence of eyewitnesses, showed that the girder fractured near the centre of the last span on the Saltney side.

But what did the experts have to say? The most important evidence was heard from Captain Simmons and Mr Walker, as well as Robert Stephenson and Joseph Locke.

Captain Simmons' Report

The report by the Railway Inspectorate involved detailed examination of the remains, including the fallen broken girders and damaged masonry on the bridge. The final report was actually not published by the government until 30 June 1847, shortly after the end of the Inquest on 18 June, but Simmons and Walker were able to present their preliminary observations directly to the tribunal.

They reported that the structure was composed of three spans on two masonry piers, each span having two pairs of cast-iron girders to bridge the gap. Each girder was in turn composed of three separate castings, bolted together at flanges and reinforced by semi-circular castings across the joint. Further reinforcement was provided by two wrought-iron straps (tension bars), on both sides of the girder.

They were supported on the ends of the composite girder and at the joints, running down diagonally to the first and last joints, and near the base of the centre casting. They were 6in wide and 5/16 in deep in section. The total length of each composite girder was 107.5ft, but 98ft from pier support to support. Each girder had an I-shape, with a narrow upper flange 7in wide and a wide lower flange some 3ft wide. The total height was 3ft 9in. The girders were 12ft apart but tied together by thirteen wrought-iron horizontal tie bars (4in by 1in in section) fixed to recesses moulded into the bases of the girders. The girders supported oak joists laid across on the lower flanges. They were 10in by 10in in section, and supported a track floor of 4in planks, upon which the wrought-iron rails were fixed. A guard rail – an extra set of rails – was laid 3in inside, to act against tipping wheels.

One track of the line was opened in September 1846 and was used by the contractor for trains carrying construction materials. The greatest loading on a single girder came from two locomotives and tenders coupled together (about 60 tons), without apparent damage. Just before opening, one of the new girders was found to be cracked, and replaced. The bridge had been inspected by General Sir William Pasley, Inspector General of Railways on 20 October 1846, and pronounced safe and efficient on 22 October, although at the Inquest, Pasley expressed doubts about the wrought-iron reinforcement. He thought they had little strengthening action on the cast-iron girders, but they had been used on other bridges, apparently safely. On the other hand, the spans on the Dee Bridge were considerably longer than earlier structures.

Captain Simmons went on to describe the events on the day of the accident. Six trains had passed safely over the bridge before the accident but, most significantly, about 18 tons of coarse stone ballast had been laid on the planking of each span just before the fatal train passed over. The stone was intended to improve the fire resistance of the track from sparks and cinders. The total weight of the fatal train was about 60 tons, half being concentrated at the front with the engine and tender. The driver stated that his speed over the bridge was 15 to 20mph, but Simmons thought that it was probably nearer 30mph. The train passed safely over the first two spans, and was about halfway over the final span when he felt the engine sinking below him. He instantly put on full throttle, so reaching the far bank. However, the stoker riding on the tender was thrown off and killed when it derailed and hit the parapet wall, causing some damage. The carriages decoupled and fell back into the river (1.1).

The report went on to describe the nature of the fractures to the composite girder. There were two fractures: one near the centre of the middle casting, the other near the centre of the casting at the Saltney end of the structure. The latter produced separation of a large piece (3ft long at the base and 7ft at the top) by growth of a brittle crack or cracks. The break at the centre was more complex, several separate pieces being formed by crack growth, the largest being 4½ ft at the base and 11ft at the top). The fracture was apparently clean, showing no blow holes or other obvious visible defects, although a drawing of the fracture surface was not presented in the report. Simmons said in the report that several pieces of the centre break were not retrieved from the river, a statement presumably based on reassembling the parts, and finding some missing.

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Excerpted from Beautiful Railway Bridge of the Silvery Tay by Peter R. Lewis. Copyright © 2012 Peter R. Lewis. Excerpted by permission of The History Press.
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