IT’S a hive of activity on the Forth. Tugs, barges and cranes all go efficiently about their business in the shadow of the two famous bridges.
It might be difficult to imagine at the moment but in just over four years from now, cars and lorries are due to be thundering across the third.
Work on the project has started in earnest with the first of the giant caissons – effectively moulds for the concrete foundations of the towers – now having been put in place. Before the end of the year, the first of the towers will start to emerge.
Carlo Germani, project director for the contractors, the Forth Crossing Bridge Constructors (FCBC), says: “We are into the real construction work now. We’ve done a lot of preparation and site installation work, but what we see now is the start of real work on the bridge itself.”
According to another senior figure, many of the workers are genuinely excited to be involved in what is a historic project.
“There is real excitement that we are building something really special,” he says. “It’s not just another construction job.People have come from all over the world – moved their families here.
“It’s the only place where there are going to be three bridges from three different centuries, each the pinnacle of engineering for its own time.
“And I think people are going to be surprised at how big the new bridge is – 50 metres higher than the current bridge , but elegant and thin so it doesn’t dominate the scene.”
Two caissons, the biggest the size of an eight-storey building, arrived at Rosyth last month after a seven-day journey from Gdinya in Poland, welded to their barge to stop them falling off.
After being fitted out at the dockside, the caisson for the north tower was moved into position in the Forth, the barge was submerged by seven metres, allowing the caisson to be lifted off by the massive red 60-metre sheerleg crane, which then manoeuvred it into place.
The caisson for the south tower, which is bigger, is currently floating in deep water, held by six anchors, and is due to be moved into position at the end of next week.
The caisson is sunk by filling its hollow two-metre walls with water, its contact with the rock is sealed and the sediment from inside is excavated before it is filled with special underwater concrete to form the base of the foundations. Another temporary caisson placed on top creates a dry area where the reinforced concrete foundations can be built.
Construction has changed dramatically since the building of the current bridge, which opened in 1964.
One worker on the project says: “When we look at some of the things they did, it seems amazing from a health and safety point of view – like walking up the cables.
“There’s a story about one guy who worked on the bridge and he’d been out drinking in South Queensferry but he lived in North Queenferry so he decided to walk home over the cables.”
And back in the 1880s, when they built the rail bridge, it was even worse. Up to 100 people died during the construction.
Once the foundations of the new bridge are in place, the towers will be built, climbing in four-metre sections. First will be the central tower, whose foundation on Beamer Rock does not require the caisson treatment. Work is expected to start later this year, with the north and south towers beginning to appear next spring.
The construction timetable depends heavily on weather, wind and wave – but it seems so far, so good.
Transport Scotland project manager David Climie says: “We are still exactly where we want to be – on time and on budget.”