Motorists on the A83 are being diverted from the Rest and Be Thankful due to heavy rainfall in Argyll and Bute.
Drivers will instead be taken via convey on the Old Military Road, with delays of around 20 minutes to journeys expected.
BEAR Scotland said the decision was made over safety concerns, following a hillside inspection on the main trunk road.
An inspection is due to take place on Sunday over whether to return traffic to the main route, which will be subject to the forecast improving.
Ian Stewart, BEAR Scotland’s north west representative, said: “The safety of road users is the priority for BEAR Scotland and we closely monitor conditions at the Rest and Be Thankful on a daily basis.
“This weekend’s forecast for rain will significantly increase saturation levels on the hillside, therefore we’ve decided to open the Old Military Road as a proactive safety measure.
“The use of this route maintains access to the A83 corridor for the travelling public, keeping Argyll very much open for business with minimal delays of around 20 minutes.
“Subject to the weather improving, we plan to inspect the hillside thoroughly on Sunday October 13 and this will inform a decision to return traffic to the A83.”
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