Exclusive:Inside the Queensferry Crossing as you’ve never seen it before: Monorail hidden within bridge

The Scotsman was given an exclusive tour inside the £1.35 billion structure

This is the Queensferry Crossing – as you have never seen it before.

Unbeknown to the thousands of drivers who cross between Fife and Edinburgh daily, a monorail hidden beneath the carriageways runs the length of the bridge to provide fast access to the inside of the deck for maintenance.

These exclusive pictures and video by The Scotsman’s Lisa Ferguson show the shuttle in action, along with one of a series of multi-level maintenance gantries which enable access to every part of the underneath and sides of the deck.

Monorail shuttle "The Rat" travels the length of the 1.6-mile bridge under the carriageways. (Photo by Lisa Ferguson/The Scotsman)

The Scotsman was granted the first media access by bridge managers BEAR Scotland to take a tour of features of the 1.7-mile-long bridge that have remained out of the pubic gaze since it opened six years ago.

The shuttle – nicknamed “The Rat” because it runs along a tunnel – can travel up to 8.5mph, allowing bridge staff, equipment and materials to be transported quickly along the structure, which saves hours of walking during regular routine inspections.

The monorail operates inside a box girder – a hollow rectangular tube – which carries the roadway, passing close to the crossing’s three towers. It has space for two people, who sit back-to-back, and is operated by controls inside the cabin.

Chris Tracey, BEAR Scotland’s south east unit bridges manager, said: “It’s mainly used for inspections, so the principal advantage is time – we can get to a work site quicker and work for longer, otherwise staff would have to stop earlier to walk back at the end of a shift.

A walkway inside the bridge deck which runs parallel to the monorail shuttle. (Photo by Lisa Ferguson/The Scotsman)

"You can put small hand tools in it, so they don’t have to be carried on foot. It is also safer, there’s no question about it. Anything that improves access is beneficial."

Walking over open-floor grating beside the shuttle’s track, which stretches as far as the eye can see, it feels like being in the open hull of a ship, albeit more than 160ft (50m) above the Forth. Orientation maps along the way prevent workers from getting lost.