Work will finally get under way at a blackspot Mearns junction on Monday.
Eight weeks of ground investigations will start at the A90/A937 Laurencekirk junction in a move that has been eagerly awaited by campaigners.
The trunk road has previously been named one of the most dangerous in the UK, with the Laurencekirk stretch the scene of a string of fatalities.
The work is a preliminary step before a flyover is built at the site.
Florist Jill Fotheringham from Laurencekirk has spearheaded the fight for improvements.
She said she had grown tired of being asked to produce wreaths at her shop in Montrose for accident victims and began the campaign for action in 2004 following the death of a local man at the junction.
Her efforts paid off in January 2016 when the Scottish Government announced £24 million for the design and construction of a grade-separated junction improvement at Laurencekirk as part of a package of additional investment alongside the Aberdeen City Region Deal.
Contractor Amey was appointed to take forward the development work in September that year.
Ms Fotheringham said she was “absolutely delighted” to see the work begin.
“I’m sure everyone will cope with any delays knowing that the outcome of this is our long overdue flyover,” she said.
Transport Scotland has warned some traffic management measures will be required to allow work on or near the carriageway to be carried out safely.
This will include alternate single file traffic sections on the adjoining A937 side road, which will be controlled by temporary signals or stop/go boards.
A Transport Scotland spokesperson said: “We are continuing to progress the design work for the much-needed Laurencekirk Junction Improvement scheme, having let the public see and comment on the preferred option for the scheme last summer.
“We are now taking forward the detailed design of the preferred option with a view to publishing draft orders later this year, and these ground investigations will provide the detailed information needed to progress that work.
“We apologise for any inconvenience these works will cause and would thank road users and local communities in advance for their patience during the works. The contractor will closely monitor the operation of the traffic management measures to ensure that delays are kept to a minimum.”
Drivers are asked to plan their journeys in advance using the Traffic Scotland website and Twitter feed.