Transport Scotland’s term maintenance contractor Bear Scotland has said that the A83 Rest and Be Thankful and Old Military Road remained closed last night as further landslip assessment was undertaken.
Inspections undertaken following the multiple landslips on Tuesday have identified three large boulders – the largest estimated to weight 75t – 300m up the slope that present a risk to road traffic.
Bear said that engineers are now working to secure the boulders by drilling into the rock and inserting a device which will help break the boulders into smaller pieces on the hillside, reducing the risk of further movement on the slope.
Teams have been using a helicopter to carry out aerial assessments and bring machinery and materials to address the boulders on the hillside. Geotechnical engineers have also been assessing the slope on foot.
Some 2,500t of material is estimated to have reached the catch-fences along the A83 carriageway following multiple landslips after prolonged heavy rain on Tuesday.
Over the past six years, the range of landslip mitigation measures installed at the Rest and Be Thankful is estimated to have prevented the A83 from closing for at least 23 days in total and the current closure have been put in place to allow inspection of the rock catch fencing.
Bear Scotland north west network manager Tommy Deans said: “Safety is our number one priority and we cannot open the A83 or the Old Military Road until these boulders high-up above the carriageway are made safe.
“Tuesday’s landslips have caused a number of boulders to become exposed which is causing some concern, and we want to be as confident as possible that there will be no further movements of material or the boulders on the hillside before we open the Old Military Road as a diversion which sits below the A83 carriageway.
“Our next steps are to work with geotechnical colleagues to safely secure these boulders and remove the threat of any further movement on the hillside, which they are working to do this afternoon and work on this resumed at first light this morning.
“Teams have worked throughout the day to clear around 150 tonnes of debris from the Old Military Road in preparation for the route to be used as an alternative local diversion route, however this will not be used until we are confident that the road is safe.
“After that, teams will then turn to emptying and securing the material caught above the A83 carriageway in the debris fences.
“We continue to thank the travelling public for their patience while we do everything we can to address yesterday’s landslips. We encourage road users to follow the diversion route via Dalmally or to find an alternative form of transport. We advise motorists to check ahead with Traffic Scotland for real-time journey information.”