The A83 is closed tonight after a huge boulder was discovered sitting precariously above the road at the Rest and Be Thankful.
A 50-mile diversion via the A82 Inverness to Glasgow road is being put in place.
A spokesman for Bear Scotland, the maintenance company for the Tarbet to Campbeltown road, said: “During a geotechnical assessment today at the site on the Rest and be Thankful which was subject to the landslip on December 30 2015, a 150 tonne boulder some 175m (574ft) above the A83 has been identified as being at risk of mobilising.
— Traffic Scotland (@trafficscotland) January 4, 2016
“Following this assessment a decision has been taken to close the A83 overnight in the interest of safety. This same risk currently applies to the preferred Old Military Road diversion route. The alternative diversion via Dalmally is currently being implemented.
“The route will re-open around 9am tomorrow morning under convoy control utilising the Old Military Road local diversion route when the appropriate safety measures have been put in place. Work will then commence to remove the boulder using explosives. It is anticipated that this will take around two days.
“Access will be maintained from Inveraray to Lochgoilhead, and Dunoon where ferries offer an alternative route via Gourock.”