The A83 at the Rest and Be Thankful has been closed due to multiple landslips.
The road has been closed in both directions after heavy rainfall across Argyll and the usual alternative route, the local Old Military Road, has also been blocked due to the landslip.
Both roads will remain closed overnight and safety assessments will take place first thing in the morning.
A diversion route has been put in place between Tarbet and Cairndow via the A83, A82, A85 and A819.
A day of challenging conditions saw heavy rain and flooding impact a retaining wall at Inveruglas on the A82 as temporary traffic lights have been put in place.
It is estimated that 65mm of rainfall fell at the Rest and Be Thankful today.