The scenic route to Bervie Braes in Stonehaven will remain closed until the end of the year following a “minor” landslip.
The road has been a major concern for decades, with Aberdeenshire Council spending millions on safety measures to stop collapsing material and protect residents.
An economic impact assessment determined the route – which offers scenic views for visitors arriving from Dunnottar Castle – could be worth up to £9million to the area.
Following a large landslip in 2009 that resulted in dozens of homes being evacuated, a £3.3million stabilisation project was commissioned on the lower slopes.
But after a small landslip in October, the council has now announced a second line of barriers will be installed in the carriageway.
These will provide increased capacity for debris for future cases of possible slips.
Officials had hoped to reopen the road with an enhanced monitoring system in place while investigations were under way.
However, it was determined the instability of the slope was “far more extensive” than previously anticipated and posed an “unacceptable risk” to motorists.
While the road will be closed for vehicles for safety reasons, the pathway will remain open for pedestrians and cyclists.
A spokesman for Aberdeenshire Council said: “Following investigations into the stability of Bervie Braes at Stonehaven following a minor landslip late last year, we have had to close the route to vehicular traffic for the remainder of the year with immediate effect.
“The additional barriers will also control any possibility of debris flow onto the top of the lower slope.
“We appreciate the closure is disappointing news for many of you and we ask for your patience as the investigations continue.”