Landslides have closed a number of roads at the Rest and Be Thankful at rush hour, with drivers facing a detour of around 60 miles.
Emergency services are on the scene with the A83 closed in both directions from Arrochar to the A815 at Dunoon.
It comes after a landslip at the closure-prone Rest and Be Thankful, with an original diversion via the B839/B828 Lochgoilhead not in use due to a further landslide.
Diversions are in place via the A819, A85, and A82, and the Old Military Road diversion is also not in use.
Some drivers are facing a 60-mile detour to their journey.
Police and BEAR Scotland are in attendance at the scene with debris on the road at Butterbridge and Glen Kinglas.
Drivers are advised to use an alternative route and expect delays in the area.
A Police Scotland statement read: “Following a landslide on the Rest and be Thankful, the A83 is closed in both directions from Arrochar to the A815 at Dunoon.
“Unfortunately, due to a further landslide, the original diversion via the B839/B828 Lochgoilhead is now also no longer in use.
“Diversions are in place via the A819, A85 and#A82.
“Please note that the usual Old Military Road diversion is NOT in use.
“Police and BEAR Scotland are in attendance.”
BEAR Scotland said: “Our operational emergency team is on site assessing the situation, which will also require geotechnical inspection in daylight prior to commencing clear-up, for which resources are being mobilised.”
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