Gantry solution bridges technical challenges

The ingenuity and innovation we bring to high-level bridge works has come to the fore in one of the most technically challenging projects we have ever delivered.

In one of our latest projects on a landmark structure, we have designed and installed an innovative under-deck mobile gantry on Kessock Bridge, which crosses the Beauly Firth at Inverness in Scotland.

The bridge’s existing gantry required replacement, as it had come to the end of its structural design life, and we have used our in-house expertise to design a unique new gantry, which will enable year-round inspection and maintenance.

Our purpose-built gantry is able to move along the full 1km length of the bridge and follows the complex geometry of the crossing while the platform holding the operators remains level. The gantry has a scissor lift at each end of the platform, allowing operators easy access for maintenance and inspection of the bridge overhead.

The project also involved a detailed dimensional and structural condition survey, inspection, refurbishment and repair of the existing rails under the bridge deck, which the gantry moves along.

As part of the project, the gantry parking area at the north side of the bridge has been upgraded to allow the gantry to be safely stored and maintained when not in use.

Improvements to the gantry infrastructure have been installed in the form of dedicated charging points along the length of the bridge at selected piers, so the gantry can be plugged into an electrical supply when not in use, ensuring optimum maintenance and prolonging its operational life.

In addition, bespoke work has been completed to put in place an appropriate emergency escape strategy from the gantry, to address a challenge often encountered in high-level maintenance situations.

The project is being delivered for BEAR Scotland Ltd, who are the trunk road management and maintenance agent, on behalf of Transport Scotland (part of the Scottish Government), in the north-west area of Scotland. We’re now in the final stages of commissioning and the project is expected to be fully completed early in 2021.

Luke Fisher, our Sector Lead (Bridges and Structures), said:

“We believe this is one of the most complex mobile access gantries developed for any structure anywhere in the UK and it is completely bespoke to this bridge.

“It demonstrates our capability in multi-disciplinary engineering as it combines mechanical, structural and electrical expertise. Bringing all of these elements together is where the true innovation comes in.”

Take a look at the gantry in action on Kessock Bridge below.