The refurbishment work is being undertaken by Balfour Beatty which has won the contract to deliver a range of vital maintenance projects around the 130-year-old structure.

The north approach span, which carries the railway over North Queensferry, will be repainted with the same glass-flake epoxy paint system used to restore the bridge itself during the decade-long, £130m refurbishment programme completed by Network Rail, and main contractor Balfour Beatty, in 2011.

Engineers will soon begin to encapsulate the approach span in a protective scaffold casing before grit-blasting the layers of old paint off the steelwork to allow inspections to take place.

The metal will then be repaired and repainted. The new paint system will mean the steel will not need repainted for up to two decades.

Balfour Beatty will also undertake a range of other works as part of the contract – including maintenance and monitoring of the bridge bearings, refurbishment of staff welfare facilities on the structure and refurbishment of the Inchgarvie lighthouse.

The refurbishment works will be completed without disruption to train services.

Alan Ross, Network Rail Scotland’s director of engineering and asset management, said: “The Forth Bridge has been a key part of Scotland’s Railway for over a century and this work on the approach spans to the famous structure is vital to ensure we continue to maintain a safe and reliable railway.

“Balfour Beatty have been supporting our restoration and maintenance programmes on the bridge for two decades and will bring a wealth of experience to this latest project.

“We are also committed to delivering this vital investment in Scotland’s Railway with a minimum of disruption to the local community and without interrupting train services.”

Colin Hardie, regional construction superintendent for Balfour Beatty’s Scotland and Ireland business, said: “This award is testament to our collaborative relationship with Network Rail, having first been contracted to deliver restoration works on the Forth Bridge in 2002.

“Our expert team takes great pride in restoring a structure with such global significance and we look forward to beginning the new refurbishment works so that Forth Bridge can be enjoyed by the many for generations to come.”

The work is part of Network Rail Scotland’s five-year, £4 billion programme of investment in Scotland’s Railway between 2019 and 2024.