The A83 Rest and Be Thankful is set to reopen on Monday.
The Argyll and Bute road has been closed for almost five weeks after a landslip brought down 6000 tonnes of debris amid heavy rain on August 4.
The Old Military Road (OMR), used as an alternative route, was also forced to close following the torrential downpour – leaving a 60-mile diversion. The OMR has since reopened.
Teams from BEAR Scotland have been working “round the clock” since the landslip.
Repair work has included creating a concrete retaining wall to stabilise the roadside, building up and securing the embankment using large soil nails, installing a new culvert beneath the road and a new road surface.
Work is also under way on a new roadside drainage system and safety barrier.
Eddie Ross, BEAR Scotland’s north west representative, said: “Our teams are continuing with the repairs on the A83 following last month’s landslide, working round the clock to complete the work.
“We’re expecting to reopen one lane of the A83 under traffic light control on Monday, weather permitting.
“Teams will continue work on the A83 once the road reopens with further mitigation measures being installed at the bottom of the steep channel next to the roadside to create further protection for the A83.
“Work has also begun at the next permanent catch-pit further along the A83. Together these measures will help contribute to additional resilience on the A83.”
Meanwhile, the storm-damaged A68 trunk road near Fala in Midlothian has reopened under temporary traffic lights.
The key route linking the Borders and Edinburgh suffered a partial collapse last month, resulting in a 27-mile diversion for drivers.
Around 5000 tonnes of stone was needed to rebuild the 20m-deep embankment that was damaged in the storm.
Bear Scotland said traffic lights have been put in place to allow for final repairs. They are expected to be removed later this week.