Picture caption: The Forth Road Bridge with the iconic Forth Bridge in the background

Bridge enthusiasts will have the opportunity to see behind the scenes at the Forth Road Bridge later this month, with two lucky people getting a trip to the top of one of the bridge’s main towers.

At the time of writing, the tours were sold out, but any visitors who attend on the day – where you can still enjoy the visitor’s centre and take a walk across the bridge – will be able to enter the charity prize draw to win that once-in-a-lifetime trip up one of the 156m (512 feet) towers.

The tours are part of Scotland’s Doors Open Day Festival, where members of the public can go behind the scenes of historic buildings and vehicles including vintage buses, restored railway stations and lighthouses.

The bridge tour is a brilliant opportunity, and a perfect chance to see the two neighbouring bridges, the iconic Forth Bridge and the newer Queensferry Crossing – a 2.7km (1.7 mile) structure which is the longest 3-tower, cable-stayed bridge in the world.

The Forth Road Bridge opened in 1964 and at the time it was the fourth longest in the world and the longest outside of the United States. It’s a long span suspension bridge and, including the approach viaducts, it is just over 2.5km (1.5 miles) long. The span between the two main towers is 1,006m (3,300 feet).

An incredible 125,000m³ of concrete and 39,000 tonnes of steel were used in the construction of this bridge. Of course, it requires regular maintenance. All the hanger sets – 192 sets of four hanger ropes which drop down from the main cables, supporting the suspended bridge decks – were replaced between 1998 and 2000. This was carried out without closing the bridge.

Today, the loads on the bridge are higher than expected due to the increasing weight of vehicles and the sheer number of heavy goods vehicles using the bridge. There’s an ongoing programme to strengthen the bridge in light of the additional loads it needs to bear.

Anyone lucky enough to get a tour ticket will get to see parts of this bridge that are usually hidden from view, and to enjoy hearing from staff who’ve worked on the bridge for many years. Bridges are always interesting structures, so I’m almost tempted to go along and see if I can take up a spare tour slot, despite the distance from Twickenham.

In the meantime, if you need assistance with the structural elements of an upcoming project, please do get in touch.