North-east rail passengers will face two months of bus replacement services next year.
The Evening Express can reveal the planned closures of the Aberdeen to Huntly line as part of the £300 million scheme to dual the track between Aberdeen and Inverness.
Work on parts of the stretch will begin in May with closures expecting to last 15 weeks.
The line will be shut between Dyce and Inverurie from May 3 to June 14, Dyce to Huntly from June 14 to August 9, and between Aberdeen and Huntly from August 9-19.
It is understood the eight-day closure between Aberdeen and Huntly in August is so the transport body can commission the signalling system across the newly doubled sections.
Network Rail said ScotRail will be running a replacement bus service which will follow a similar format to last year when Aberdeen to Dyce was closed.
A spokesman said engineers would be working “around the clock” to finish the project and hoped any disruption to passengers would be minimal.
He said: “The Aberdeen-Inverness Improvement Project will transform train travel between the two cities and the work we are undertaking next spring is vital to the successful delivery of the project.
“Our engineers will be working around the clock to complete this complex programme as quickly as possible for customers and to keep disruption to line-side communities to a minimum.”
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Preparation work has already begun for the doubling of the track next year.
Once the project is completed, the rail operator has said train journeys will be improved, with half-hourly services between Aberdeen and Inverurie providing an extra 3,000 additional seats every day.
The project will also see an extended platform at Insch and a new service between Inverurie and Montrose, meaning passengers will not need to change at the Granite City.
Previously 12 miles of rail was laid between Aberdeen and Dyce this year during a 14-week closure as part of the ongoing Scottish Government funded improvements.
Five bridges between Aberdeen and Dyce were also refurbished in the works that saw 1,640 concrete blocks, weighing more than 5,000 tonnes, installed along the railway line at Kittybrewster, Woodside, Bucksburn and Stoneywood.
The work will also provide extra capacity on the line to deal with new stations at Kintore and Inverness Airport and more through services to the central belt via Aberdeen.