Boulders the size of cars are among 6,000 tonnes of debris that slid down a hillside and blocked the A83 at the Rest and Be Thankful and its usual diversion route, a road management organisation has said.
Landslips once again hit the road amid heavy rainfall on Tuesday, closing it in both directions, along with the Old Military Road (OMR), previously used as an alternative route when the main road is impassable.
Politicians called on the Scottish Government to take action to prevent the recurring landslips.
Road management and maintenance organisation BEAR Scotland said initial clear-up operations have started after geotechnical specialists carried out safety inspections at first light on Wednesday.
Roadside assessments the previous day indicated it was then unsafe to attempt to clear the road or carry out further investigations due to the risk of further landslips.
BEAR Scotland said 6,000 tonnes of debris crashed down the hill from 200 metres above the road as up to 100mm of rain fell in the region.
The heavy rain created a “fan effect” down multiple water channels, some of which reached the roadside.
Approximately 1,500 tonnes of debris is thought to have reached the A83 and about 2,000 tonnes washed on to the Old Military Road.
Car-sized boulders were brought down the hillside on to the carriageway.
One of landslip mitigation catch pits recently installed in a bid to prevent debris reaching the road caught about 2,000 tonnes from one of the channels carved into the hillside.
The slope is being inspected to assess the risk of further boulder falls.
Eddie Ross, BEAR Scotland’s north-west representative, said on Wednesday: “Yesterday’s heavy rain caused a large landslip high above the road which reached the A83 and OMR roadside at multiple points, bringing significant amounts of debris.
“Our teams have mobilised at both ends of the A83 at the Rest and OMR and have begun the initial clear-up of the debris.
“Further assessments need to be completed by geotechnical specialists of the hillside and both roads to check for any further concerns, and until these checks and the clear-up is complete the A83 and OMR will remain closed.”
He added: “In the meantime, Argyll remains open for business and we encourage road users to follow the diversion route in place for motorists.
“Western Ferries are also running additional sailings for their Gourock to Dunoon crossing to accommodate road users.”
A 59-mile diversion route has been put in place between Tarbet and Cairndow via the A83, A82, A85 and A819.
Argyll and Bute Council leader Aileen Morton has written to First Minister Nicola Sturgeon calling for action.
She said: “This is now the second landslide of the year that has closed the Rest and Be Thankful and resulted in disruption to a major trunk road causing havoc for our communities, businesses and visitors.
“It is abundantly clear that mitigation measures taken by Scottish Government have yet again failed the people of Argyll and Bute.
“Taking such a shilly-shally approach is simply no longer acceptable and we, as a council are asking again for a permanent solution to be identified, funded and delivered as a matter of urgency.
“The issues on the Rest and Be Thankful have been debated, investigated, patched up and largely ignored for the last decade and we still find ourselves in this same position again.”
Scottish Greens transport spokesman John Finnie echoed her call, saying: “The Scottish Government must urgently rejig its roads budget and provide Argyll respite from a 60-mile diversion I wager would not be acceptable anywhere outwith the Highlands.”