Forth Bridge

Listen first. Somewhere above you, a train is crossing. The sound arrives late, a low steel rumble that rolls down through the girders and out across the water. Gulls cry over the estuary. The air smells of salt and wet stone. Then you look up, and the red shapes fill the sky. Three enormous diamond-shaped towers stride across the Firth of Forth, linked by long arms of steel. This is the Forth Bridge, and it has carried trains across this water since 1890.

You are standing on the edge of the Firth of Forth, the wide estuary where the River Forth meets the North Sea. On the north shore is North Queensferry, in Fife, a short drive from Dunfermline. On the south shore is South Queensferry, on the Edinburgh side. For centuries, people crossed here by ferry, which is how both villages got their names. The bridge replaced a slow and often stormy boat journey with a few minutes on a train.

The story of this bridge begins with a disaster. An earlier engineer, Thomas Bouch, had designed a suspension bridge for this crossing. But in December 1879, his Tay Bridge, further north near Dundee, collapsed in a winter storm while a train was crossing. Everyone on board died. Public trust in Bouch was gone, and his Forth design was abandoned. Whatever came next had to look strong, and had to be strong, beyond any doubt.

The new design came from two engineers, Sir John Fowler and Sir Benjamin Baker. The main contractor was Sir William Arrol, a Glasgow builder. They chose a cantilever design. A cantilever is a beam fixed at one end and free at the other, like a diving board. Here, each tower supports two arms reaching outward in opposite directions. Short central girders then join the arms of neighbouring towers together. The result is a chain of balanced structures, each one holding itself up.

Here is a detail many visitors miss. To explain this idea to the public, the engineers staged a famous photograph. Two men sat on chairs, holding wooden poles with their arms, forming two living cantilevers. Between them, a third man sat on a plank, playing the part of the central girder. That man in the middle was Kaitaro Watanabe, a Japanese engineer who worked on the project. The photograph is still used in engineering lessons today.

The bridge was also one of the first great structures in the world built mainly from steel rather than iron. Steel was stronger, and the engineers needed that strength. Each main span between the towers is about 520 metres long. When the bridge opened, these were the longest cantilever spans in the world. They kept that record for nearly three decades. The whole crossing runs for roughly two and a half kilometres from shore to shore.

Now look at the three towers. The middle one stands on a small rocky island called Inchgarvie. The other two stand near each shore. Their foundations were built using caissons, which are huge watertight chambers sunk into the riverbed. Men worked inside them under compressed air, digging down into mud and rock. It was hard and dangerous work. Some suffered from the pressure sickness that divers also know.

Building the bridge took most of the 1880s, and thousands of men worked on it. Dozens of them died, falling from great heights or struck by tools and steel. For many years the official count was lower. Later research by local historians found more names, and the number has risen. A memorial now remembers these workers by name. As you look at the steel, it is worth remembering the people who put it there.

In March 1890, the Prince of Wales, the future King Edward VII, opened the bridge. He drove in a final ceremonial rivet, which had been gilded for the occasion. Speaking of rivets, there are millions of them holding this structure together. Each one was heated until it glowed, then hammered into place by hand. If you look closely at the steel near the shore, you can still see their round heads in long, neat lines.

And then there is the colour. The bridge is painted a deep rusty red, and the shade has become almost a part of its identity. In Britain, people once said a never-ending job was like painting the Forth Bridge. The idea was that, by the time painters reached one end, the other end needed painting again. In the early 2000s, a long restoration gave the bridge a modern, much more durable coating. The old saying, at last, has a little less truth in it.

This is still a working railway. Passenger and freight trains cross it every day, more than a century after it opened. The bridge also had a moment on the cinema screen. In Alfred Hitchcock's 1935 film The 39 Steps, the hero escapes from a train as it stops on the bridge. In 2015, UNESCO named the Forth Bridge a World Heritage Site. That status places it among the most important places on Earth for human culture.

Turn your head, and you will notice something unusual. The Forth Bridge is not alone. Further upstream stand two more bridges. The Forth Road Bridge, a suspension bridge, opened in 1964. The Queensferry Crossing, with its slender white cables, opened in 2017. So three bridges from three different centuries stand side by side here. Each one shows how engineers of its time solved the same problem of crossing this water.

If you have time, walk along the shore in either Queensferry. The angles change with every step. From some points, the towers line up and seem to overlap. From others, you can see sky through every gap in the steel. Boat trips also run on the firth at some times of year, giving a view from below. On a grey day, the red steel stands out even more clearly against the water.

Before you leave, stay still for a moment. Watch the light move across the girders. Wait for the next train, and listen to the rumble roll down from above. Notice how small the carriages look against those towers. Then let your eyes follow the steel down to the water, to the stone piers, to the rivets the size of a thumb. All of it was shaped by hand. And all of it is still holding.