A487 Tal-y-Llyn landslide work continues in Gwynedd
Motorists heading between Machynlleth and Dolgellau in Gwynedd could face a 20 mile (32km) detour until the weekend.
It follows the landslide on the A487 at the Tal-y-Llyn pass on Monday, which saw boulders cascade onto the carriageway.
The debris has forced authorities to close a stretch of road between Cross Foxes and Dyfi bridge.
One boulder was estimated to weigh about 10 tonnes.
Work to reopen the road is being carried out by the North Wales Trunk Road Agency.
Gwynedd council said it receved a call about the landslip at 0320 BST on Monday.
"An assessment has been undertaken of the site, and work is being carried out to ensure that the road is safe, before it can be re-opened," said a spokesperson.
"We expect that the road will be re-opened in the coming days. In the meantime, diversions are in place."
Motorists are being forced to re-route their journeys from Dolgellau via Mallwyd, adding about 20 minutes to the journey to Machynlleth.
Diversions in place are:
- Southbound: A470 through Mallwyd to Cemmaes Road then proceed along A489 Cemmaes Road to Machynlleth.
- Northbound: A489 Machynlleth to Cemmaes Road then A470 through Mallwyd.