The Forth Bridge
A symbol of innovation, strength and Victorian vision, the Forth Bridge is a rugged piece of engineering built to endure in a harsh environment
Nomination: Here is a structure that needs no introduction. That giant vision of red girders spanning the Firth of Forth really does deserve the title ‘iconic’. It’s vast, yet elegant, and fully deserves its UNESCO World Heritage Site status.
The bridge combined the engineering genius of Sir John Fowler (Metropolitan Railway), William Barlow (St Pancras roof) and Sir Benjamin Baker (Aswan Low Dam). It may look over-engineered but it was designed in response to the collapse of the Tay Bridge - and, 130 years after it was built, it’s now carrying nearly 200 trains a day.
Any structure that becomes a simile - “as long as painting the Forth Bridge…” - surely deserves to be a wonder of the railway.
It would have been a great surprise if the iconic Forth Bridge had not made it into the Seven Wonders of the Railway. Voted as Scotland’s greatest man-made wonder in 2016 and designated a UNESCO World Heritage Site, it is a marvel of Victorian engineering like no other.
Opened in 1890, the Forth Bridge is now a quarter of the way into its second century in existence, and carries traffic far heavier than its designers and builders had ever imagined. Spanning the Firth of Forth, from Fife on the north bank to Edinburgh and Lothians on the south, the bridge was designed by English engineers Sir John Fowler and Sir Benjamin Baker as a winning entry in a competition to find an alternative solution to the ferry link that existed at the time.
There had been tunnel proposals in 1805 that came to nothing, and a suspension bridge proposal by Sir Thomas Bouch in 1871 (but he was discredited after the collapse of the Tay Bridge in 1879, so this also never came to pass).
Work began on the epic construction project in 1882 and, for the next eight years, a total of 4,600 men worked on the build. There are conflicting reports as to how many of those men lost their lives during construction, but the figure is close to 100. It had been estimated that it would take 42,000 tonnes of steel to construct, but in reality the figure was closer to 53,000. A staggering 6.5 million rivets were all heated on-site in oil-fired furnaces and hammered into place.
The figures involved in the bridge’s construction are eye-watering. The final structure is 2,467 metres in length, which is just over 1.5 miles. At its highest point, the bridge stands 110 metres above the water and 137 metres above its foundations. The piers were constructed from 120,000 cubic yards of concrete and masonry, which are faced with 2ft-thick granite.
It is a giant in every sense. Each of the main spans consists of two 680ft arms, which support a central 350ft span truss. The two main cantilever spans are 1,700ft, plus two side spans of 680ft and 15 approach spans of 168ft. Upon completion, this made it the longest single cantilever bridge span in the world (now it takes second place behind the Quebec Bridge in Canada). The Forth Bridge was also a pioneer for other reasons - it was the first major structure in Britain to be built of a then-untried and untested material - steel - rather than the more common wrought iron. With all that steel, painting the Forth Bridge is a serious feat in itself. In 2001, Network Rail began a task which is often portrayed as never-ending, with the assistance of principal contractor Balfour Beatty. The bridge had been suffering from over a century of beating by the harsh Scottish weather, and exposed old paint layers were flaking off the steel.
On December 9 2011, the sometimes 400-strong team finished a decade-long repainting job that had involved shot-blasting and painting the bridge’s 230,000m2 of steel with 240,000 litres of paint.
It’s also not just any old paint. The coating on the Forth Bridge is one of the world’s best technical paints, developed and manufactured by Leighs of Bolton. The colour is officially known as ‘Transgard TG168’, but it’s far more commonly known as ‘Forth Bridge Red’! It is only ever used on the Forth Bridge and nowhere else. This highquality paint is expected to last for 20 years, which is a good job considering it takes half that time to paint the whole structure.
This was the first time in its history that the structure had been entirely repainted.
There are now 1,040 lights installed throughout the bridge, that use around 35,000 to 40,000 metres of cable. All those lights are necessary when you consider that 200 trains now use the bridge every day, carrying approximately three million passengers every year. After all, it was the Forth Bridge that created an unbroken East Coast Main Line from London all the way to Aberdeen.
These words from the successful nomination to register the Forth Bridge as a World Heritage Site encapsulate exactly why this icon deserves to be recognised as one of RAIL’s Seven Wonders of the Railway:
“The Forth Bridge is a globally important triumph of engineering, at once structural and aesthetic… It represents the pinnacle of 19th-century bridge construction and is, without doubt, the world’s greatest cantilever trussed bridge…
“No other trussed bridge approaches its perfect balance of structural elegance and strength, nor its overall scale, and no bridge is so distinctive from others as is the Forth Bridge from its peers.”