Picture courtesy of National Records of Scotland Ref: NRS BR/FOR/4/34/161, The human cantilever: three men positioned to model the cantilever principle, 1887 (AAA01407).
and, —— A more up to date take on the human cantilever system !
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The Consulting Engineer
Sir John Fowler (1817-1998) was one of the great civil engineers of the Victorian railway boom. He designed a number of bridges – including the Grosvenor Bridge, which carried the first railway across the Thames – and designed Victoria Station in London and stations in Glasgow, Sheffield, Liverpool and Manchester. Manchester Central Station’s 64m-wide train shed roof was the second widest unsupported steel arch in the country, after the roof of St Pancras Station.
Some of his most memorable work, though, was as a pioneering engineer on the various lines which became the London Underground.
He was also involved in engineering and railway work abroad, with projects in Algeria, Egypt, Australia, Belgium, the United States, Germany, France and Portugal.
In 1865 he became the youngest ever president of the Institution of Civil Engineers and was active in leading the development of training for engineers.
By the time he came to his work on the Forth Bridge he had passed much of the design work on to Benjamin Baker, but he remained the senior partner throughout the construction and was made a baronet on completion of the bridge in 1890.
The Contractor
William Arrol (1839-1913) was the classic Victorian ideal of the self-made man, rising from humble origins to fame and a knighthood through hard work and ingenuity.
Beginning work in a cotton mill at the tender age of nine, he became a blacksmith’s apprentice at 14.
He joined a Glasgow firm of builders and bridge makers in 1863 and just five years later was able to launch his own business on his life savings of £85.
He established his Dalmarnock Works in 1872 and within three years built his first major bridge, taking the North British Railway across the Clyde at Bothwell.
He won the contract to build Bouch’s planned suspension bridge across the Forth and, when that was halted, he won the contract for the successful Baker and Fowler design.
In a work schedule which didn’t ease with success, he was also the contractor for the new Tay Rail Bridge, and a typical week would see him spend Monday morning at his works at Dalmarnock before going for two days to the Forth, two days to the Tay and one back at Dalmarnock – before getting on the train to London to consult with Fowler and Baker on the Saturday and sometimes the Sunday too.
By the time he was knighted for his work in 1890, he had already started work on London’s Tower Bridge (opened 1894) and future contracts would include the Wear Bridge at Sunderland and the Nile Bridge at Cairo.
Two of then final designs, showing the accepted version second.
The Forth Rail Bridge:
Construction
“From the Network Rail Corporate Archive“
The Forth Bridge was the first major structure in Britain to be constructed of steel (rather than iron) and this was only possible because of an advance in steel manufacture.
Large amounts of steel had become available after the invention of the Bessemer process in 1855 but its strength was unpredictable.
It wasn’t until the development of the Siemens-Martin process in 1875 that steel of consistent quality could be obtained. The steel used was produced by two steelworks in Scotland and one in Wales.
The cantilever design of the bridge was not new – it had been in use for centuries in the east – but the scale of the Forth Bridge was completely unprecedented, as were many of the technical challenges.
With the Tay Bridge disaster fresh in everyone’s mind, the designers and engineers had to consider calculations for wind pressures and the effects of temperature changes, yet they still created what, at the time, was the longest cantilever bridge span in the world and even yet is the second-longest single span cantilever.
Although work on the foundations of the Forth Bridge started in February 1883, work at the site had begun in 1882 with the construction of steel fabrication workshops on the south side of the river.
At the peak of work about 4,600 men were employed on the construction. It was long said that 57 died during the building of the bridge, although recent research by local historians indicated 63 would be a more accurate figure. The number of injuries is unknown, although one log book of accidents and sickness had 26,000 entries, and hundreds of workers were said to have been left crippled by serious accidents.
Efforts were made to look after the welfare of the men, however. Safety boats saved eight men from drowning. Boots and waterproofs were supplied to men working on the foundations, with thick woollen jackets, overalls and waterproof shoes given to those in superstructure work. Shelters and heated dining rooms were provided on-site and both workers and employers contributed to a sickness and accident fund. Wages on the project were also above average for all classes of worker.
During the seven years of construction, work was carried out from almost 100 feet below the surface of the water to over 300 feet above the surface.
The first three years were spent building the granite piers on which the bridge was to be supported. This was done by sinking caissons – great wrought iron cylinders – to the sea bed and pumping them out so that men could work on the floor of the Forth, creating foundations and building up the piers. This was dangerous and unpleasant work and, in two of the caissons the depth was such that water had to be kept out by filling the working chamber at the bottom with compressed air, the men going through air locks to get to their work.
Work on the superstructure got under way in 1886 and the growing structure became a site of wonder as it grew out from the piers, growing first upwards as the towers were completed, and then outwards as the cantilevers stretched out to meet one another, seemingly defying gravity as they did so.
The bridge was completed in December 1889 and the following month it underwent load testing. Two trains, each comprising three locomotives and 50 wagons loaded with coal (weighing in at a total of 1,880 tons for the two – twice the design load of the bridge) were driven slowly out onto the bridge, stopping frequently for measurements to be taken.
In February the first complete crossing of the bridge took place, with a train carrying the chairmen of the various railway companies involved. On March 4, 1890, the Forth railway bridge – known ever as simply The Forth Bridge – was officially opened by the Prince of Wales, later King Edward VII.
The Forth Rail Bridge:
The “Briggers”.
The Men Who Built the Forth Bridge
The Briggers, is the name given to the thousands of men who built the bridge. They were the men who toiled on a daily basis in hazardous conditions, that we would not comprehend today.
Imagine being in a rivet cage hanging from a work platform hundreds of feet above the icy Forth. Teenage rivet boys and sixty year old ex-shipyard workers faced these conditions every day. They faced many hazards, from caisson disease (the bends) working in a pressurised environment, and painter’s colic to simply being in the wrong place when scaffolding collapsed or a hammer dropped from above.
he Briggers reveals the intriguing incidentals of everyday life that make the story much more than the construction of one of the world’s great engineering feats, from the daily commute from Edinburgh by workers’ train and boat to the 200 pints lined up on the bar of the Hawes Inn at the end of a shift. The book tells of Saturday night brawls and Sunday shebeens and of the countless visitors from the Shah of Persia to pleasure steamer trippers.
For the first time the faces of individual Briggers emerge from the shadow of their bridge, thanks to the latest digital technology and the collection, recently acquired by the National Archives of Scotland, of the work of engineer Evelyn Carey, the only person officially allowed to take photographs on the bridge.
Most remarkably of all the book not only demonstrates that, with at least 73 fatalities, the death toll was significantly higher than the ‘official’ record of 57 but identifies the names and what is known of the lives of the men who died. The painstaking research by four local historians to uncover the names was the inspiration for this book. It arose from an apparently simple request from the Forth Bridge Memorial Committee who sought to give the men who died permanent recognition by erecting monuments to them on either side of the Forth.
A search through official records for a list of names drew a blank. The team then spent years of their spare time scouring contemporary newspaper accounts, death certificates and other sources to compile the first-ever list of the names of the individuals who died. During their trawl they amassed the wealth of detail about life and death on the bridge that is the basis for this book.
In 2012, twin memorials were unveiled at North and South Queensferry, by the First Minister Alex Salmond.
The event marked the end of a 10 year restoration project on the rail crossing over the Firth of Forth.
Thousands of “Briggers” have worked building, maintaining and restoring the bridge over its 129 year history.
The stone base of the 7ft bronze monuments is engraved with the words: “To the Briggers, past and present, who built, restored and continue to maintain this iconic structure.”
The Forth Rail Bridge:
Design Information.
The Forth Bridge has three double cantilevers with two 1700ft suspended spans between them, at the time the longest bridge spans in the world. As required by the Admiralty, the rail level is 150ft (46m) above high water. (as shown above). Each of the towers has four steel tubes 12ft (3.7m) in diameter and reach to a height of 361ft (110m) above high water. Their foundations extend 89ft below this into the river bed, making the total height from foundations to the top of the towers 137 metres. The total length of the bridge, including its approach viaducts is 2,467 metres. The main structure itself measures 1,630 metres portal to portal.
Baker and Fowler’s bridge was the first major construction in Britain to be made from steel; the bridge incorporates 53,000 tonnes of the material. The design of the bridge was very carefully balanced, with allowance being made for a maximum thermal expansion of 16½ inches (420mm) over the 5350ft (1630m) steel central structure. It incorporated 6.5 million rivets, which aggregated 4,200 tons weight alone. It was designed to withstand a wind force of 56lb per square foot.
Building the foundations for the vast towers started with the construction of huge caissons which were built on site and sunk using compressed air. The first of the caissons was floated into position on 26 May 1884. By 1886 all the foundations were in position ready to take the steelwork.
Thanks to the organisation and inventiveness of William Arrol, the bridge was completed in November 1889, just 6 years after work started (although at the time the weather was particularly cold and Arrol had to wait for milder weather conditions before the enormous structure expanded sufficiently for the final rivets to be inserted). Overall the bridge cost £3million to build and employed a workforce of 4,600 men at the height of construction.
The Forth Rail Bridge:
Vital Stats
Design is a cantilever construction
Total Length 8,094 Ft or 2,467 m, (1,630 for the main structure).
Maximum Width 120 ft (37 m) at the piers
Minimum Width 32 ft (9.8m) mid point between the cantilevers
Maximum Height 361 ft (110 m) above high water
Longest span 1,710 ft (520 m) either side of the center cantilever
Clearance over high water 158 ft (48 m), (Dictated by the Admiralty, for naval vessels passing below).
Foundations 89 ft below high water
Steel used 54,160 tons, and a total of 6.5 million rivets.
Granite, Stone & Concrete 79,900 Cubic metres in total.
Construction started 1882
Construction finished 1890
The grand opening March 4th 1890.
Before more modern health & safety regulations were introduced, this is how the men went about painting the bridge !
Courtesy 0f British Pathe News
As shown in this photograph from about 1995, the job of painting to protect was a necessary and ongoing task.
The never ending maintenance, but in 2012 the bridge was finally protected for the next 20 years.
The Forth Rail Bridge:
The Opening
The bridge was completed in December 1889, and load testing of the completed bridge was carried out on 21 January 1890. Two trains, each consisting of three heavy locomotives and 50 wagons loaded with coal, totalling 1,880 tons in weight, were driven slowly from South Queensferry to the middle of the north cantilever, stopping frequently to measure the deflection of the bridge. This represented more than twice the design load of the bridge: the deflection under load was as expected. A few days previously there had been a violent storm, producing the highest wind pressure recorded to date at Inchgarvie, and the deflection of the cantilevers had been less than 25 mm (1 in).
The first complete crossing took place on 24 February, when a train consisting of two carriages carrying the chairmen of the various railway companies involved made several crossings. The bridge was opened on 4 March 1890 by the Prince of Wales, later King Edward VII who drove home the last rivet, which was gold plated and suitably inscribed. The key for the official opening was made by Edinburgh silversmith John Finlayson Bain, commemorated in a plaque on the bridge.
After all testing and inspections of the bridge were completed, it was formally opened by the Prince of Wales (later King Edward VII), who drove home a final gold plated rivet, on 4 March 1890. At the same ceremony, he also knighted Benjamin Baker.
Described as the eight wonder of the world, the forth rail bridge is celebrated in this panel from the great tapestry of scotland. In 2017 the tapestry will move to a permanant base in the Scottish borders, opposite the station at Tweedbank.