A 150-tonne boulder perched dangerously above a main road was blown to pieces yesterday.
The blast to remove the huge rock at the Rest and Be Thankful was carried out 48 hours after Emergency measures were put in place to protect motorists.
The controlled explosion took place at 4.30pm after low cloud on the slope delayed earlier efforts.
The boulder, which was sitting precariously 575ft above the A83 Tarbet to Campbeltown road, was successfully broken apart using small explosives inserted into approximately 30 drilled holes in the rock.
Measuring 13ftx13ft, the hazard to vehicles passing below was discovered during an inspection following a landslide on December 30.
The A83 has been closed during daylight hours as the hillside is monitored, with the Old Military Road emergency diversion at the Rest in operation.
But in hours of darkness both roads have been shut for safety reasons, meaning that motorists face a 50-mile detour via the A82 Glasgow to Inverness road.
The Old Military Road was closed again last night as a precaution, due to the size of some of the larger pieces of boulder debris, the biggest of which is approximately a third of the size of the original boulder.
With limited daylight hours, teams were unable to complete a full safety assessment of the slope or the remaining rock fragments.
Road maintenance company Bear Scotland said it had done everything it could to complete the operation as quickly as possible.
Weather permitting, a full assessment of the slope will be carried out today.
Bear Scotland’s Eddie Ross, North West Representative, said last night: “Despite the poor weather conditions the low cloud lifted just in time for geotechnical teams to carry out the blast on the rock this afternoon.
“The boulder is now broken apart however one large section remains which requires a full assessment, and the Old Military Road will be closed overnight again as a precaution.
“We will continue the work to assess the slope tomorrow and will resume at first light.
“The continued patience of the public is very much appreciated by our team and we will continue to do all we can to get the A83 open as quickly and safely as possible.”
The work to blow up the boulder involved drilling a series of holes to weaken it every 1.6ft along the rock face.
A small explosive device was then detonated to break the rock into smaller manageable pieces. Netting was placed over the boulder to reduce the scatter of debris and any larger pieces will next be further broken down and stabilised on the hillside.
Due to the nature of the process of breaking up the boulder traffic on the Old Military Road was held for a short period to allow this to take place and restrictions were in place in the area for safety purposes.
There was considerable interest in the work from members of the public, and the car park at the Rest was temporarily closed for safety reasons.
With the Old Military Road closed, the strategic diversion via Dalmally and Crianlarich has been reinstated last night.
Overnight, the A83 remained open from Inveraray to the B828 junction allowing continued access to Lochgoilhead, Dunoon and the ferries to Gourock. At the south side of the closure, access is available from Tarbet to Ardgartan.