Recently, on the 9th December 2011, the perpetual painting job on the magnificent Forth Railway Bridge in Scotland was at last completed. here is an article from BBC News heralding the end of this task
Originally, a bridge designed by Sir Thomas Bouch was going to cross the Firth of Forth and connect Edinburgh to Fife, but the tragic disaster that befell one of Bouch’s earlier bridges, the Tay (read about that disaster here) meant that the project was suspended, and eventually taken away from him altogether after a public enquiry found that he had utterly mis-designed the tragic Tay Bridge.
The Forth Bridge project was given instead to civil engineers Sir John Fowler (who had worked on the metropolitan underground line in London) and Sir Benjamin Baker (who had transported Cleopatra’s Needle from Egypt to London), who designed the fantastic bridge that stands to this day.
The building and construction was carried out by Glasgow engineering company ‘Sir William Arrol & Co.’ and this project was groundbreaking in a number of ways;
Firstly, it was the first bridge in Britain to be made entirely of nothing but steel – a relatively unknown quantity when it came to bridges – If the Forth Bridge is compared to another bridge designed in the same decade – Tower Bridge in London, the immediate thing that is noted is that the Forth is a fairly sparse looking structure; there is nothing showy to it, is not dressed up with cladding, it is 100% function, 0% aesthetic, and in being so (in my opinion) becomes 100% both, and I can think of no Bridge in the country as industrially picturesque.
|The Forth Under Construction|
Secondly, when the bridge opened in March 1890, it was the longest single cantilever bridge in the world (though it was overtaken in 1917 by the Quebec Bridge) and was Britain’s first cantilever bridge, but these records were not made simply for the sake of it; as with the appearance of the bridge, they were purely functional.
Following the Tay disaster, public confidence in railway bridges was significantly damaged. The under-engineering of the Tay had given such structures a fearsome reputation, and to remedy this, Fowler and Baker knew that the Forth had to be the biggest and strongest bridge ever seen to restore confidence in railway bridges. The design they came up with was that of a cantilever. The strength of this design was demonstrated by co-designer Benjamin Baker at a lecture. The demonstration is shown in the picture below:
Behind the people is a photograph of the bridge, and in front of that, people act as a human version of the structure, to the same scale as the photograph of the bridge, so the men in the chairs on either side represent the vertical piers directly above them on the photograph, and the bricks next to them assume the role of the anchor piers at each end of the bridge.
The arms of the men in the chairs are supported by wooden beams held in their hands and butted against their chairs, and the tops of the two outermost ends of the beams are steadied by ropes attached to the anchor piers (or bricks) A little platform in the centre of the picture is suspended between the top ends of the wooden beams held by the inner hands of the two men.
This cantilever arrangement provided the perfect balance of forces, and supported the weight of the man sat upon the centre platform with ease. This human version of the bridge perfectly demonstrated that the bridge was well supported enough, and strong enough top cope with rail traffic.
During the building, which lasted from 1883 to 1890, five thousand men worked on the project (most of whom were foreigners) and during the seven-year build, fifty seven men died, the youngest being just sixteen years of age.
The Bridge, which was opened by the Prince of Wales upon its completion, was one of the great Victorian achievements. It was, however, quite high maintenance, and needed constant painting. In those days, and right up until forty or fifty years ago men without harnesses or safety equipment and with nothing but a flat cap on their heads climbed the steel structure with a tin of paint and a brush, coating the bridge with paint from one end to the other, and then turning around and going back again. As the article states, this task will not need to be done now for another twenty or so years due to the paint used, which sounds the death knell on the metaophor ‘like painting the Forth Bridge’ to describe a never-ending or thankless task…