The Rest and Be Thankful will reopen to motorists for the first time in 2021 following months of closure due to landslips.
From Friday, motorists on the A83 will be convoyed along the road during daylight hours, with Old Military Road, a single-track road which runs parallel to the A83 through Glen Croe, used during the night.
However due to heavy rainfall forecast for next week, the daytime use of the road on Monday and Tuesday remains under review.
A temporary barrier has been installed next to the Old Military Road, with teams working round the clock throughout the festive period to complete the work.
Geotechnical teams continue to monitor the hillside and conditions in the area, with engineers progressing with further construction work on another debris catch-pit on the A83 which will provide further resilience to the route.
Eddie Ross from BEAR Scotland said: “We’re pleased to reopen the A83 during the daytime from tomorrow after teams have completed a series of mitigation measures at road level and on the hillside above the route.
“As a safety precaution, the Old Military Road will continue to be used overnight for all road users due to the difficulties in being able to safely monitor the slopes above the A83 during the hours of darkness. Motorist safety remains our top priority and we need to ensure we are doing everything we can to keep road users safe at all times.
“With heavy rain forecast from Monday next week, it’s likely the OMR will remain in use during the daytime early next week, however we’ll continue to monitor conditions and ensure we’re putting safety first.
“The temporary bund on the OMR is nearing completion which will help provide greater protection to road users on the alternative route, giving us greater confidence in being able to keep the route open should weather conditions deteriorate.
“Work also continues on the catch-pits next to the A83, which will help provide greater resilience to the route.
“We’ll continue to closely observe the weather forecast and conditions in the area, with geotechnical teams closely monitoring the hillside.
“As ever we thank the local community and road users for their patience in advance while we do everything we can to address the ongoing situation at the Rest.”