The Rest and Be Thankful will be closed overnight due to the forecast of heavy rain.
A convoy system is currently in place on the A83 Tarbet to Campbeltown road and will continue until 4pm.
Traffic will then be diverted onto the single-track Old Military Road throughout the afternoon and into tomorrow.
A further assessment will be carried out on Friday morning to determine if the road is safe to reopen.
Persistent heavy rain is forecast in the area overnight with snow also expected in the early hours.
This will add to the high hillside saturation which has been caused by the recent spells of severe weather.
Bear Scotland has confirmed its teams will continue to have a presence on site at the Rest and Be Thankful to monitor the conditions.
A spokeswoman said: “Our team continues to have a presence on site and are monitoring conditions closely, and a further update will be issued if there is any change to the above traffic management arrangement.”
This section of the road is known for the number of landslides and debris hazards which have occurred following rainfall.
A total of 47 landslides have been recorded at the spot since 2007.
Real time travel information can be found on the Traffic Scotland website.
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