Rest and Be Thankful: Old Military Road could reopen
Engineers are hopeful the alternative route at the A83 Rest And Be Thankful - the Old Military Road (OMR) - could reopen on Saturday.
Both roads have been closed since heavy rain caused a severe landslip on Tuesday.
About 6,000 tonnes of debris shifted across the hill above the roads.
A helicopter was used to help move boulders "as big as cars" to safe locations as work continued to clear the routes.
Work continued on Friday to install additional protection measures at the OMR with the aim that it could reopen as a local diversion route from mid-morning on Saturday.
Mitigation measures
The measures included the construction of embankments along the edge of the carriageway and excavation of a channel parallel to the road as an added precaution should any material be washed towards the road from the embankment.
The mitigation measures were in place as a band of heavy rain was due in the area on Friday afternoon.
But it reopens, Police Scotland and geotechnical specialists will carry out a rigorous inspection to check all aspects of the local diversion.
Work continues to assess the damage to the A83 and the embankment above and below the road following the landslip.
Eddie Ross, from Bear Scotland which maintains the road, said on Friday: "We're on track to opening the OMR mid-morning pending a green light from the safety assessments of the diversion route following the evening's rain.
"Teams are making good progress with the ongoing construction of the mitigation measures at the OMR and we're working to having these completed later this evening."
'Assess the damage'
He added: "We'll only open the OMR as a local diversion if we are completely certain that it is safe to do so.
"We are continuing to work on the A83 and assess the damage above and below the road and work is well underway to stabilise the hillside.
"In the meantime Argyll remains open for business with Western Ferries providing additional sailings to help accommodate motorists and our teams assisting road users using the standard route."
He said safety remained the company's main priority and they would do everything possible to safely reopen both roads.
As well as a helicopter, a team of 42 people using 16 different vehicles have been working to reopen the roads.