The landslip was blocked from reaching the carriageway thanks to specially designed rock-bunds, which were the result of an innovative, sustainable engineering solution using excavated rock during the construction of further landslip mitigation measures at the Rest and Be Thankful catch-pit project just three miles away on the A83.
The landslip occurred around 230m above the carriageway following a period of heavy rainfall near midnight on Saturday night at Glen Kinglas, where teams from BEAR Scotland had been on high-alert during the Met Office yellow weather warning.
Engineers estimate that the rock bunds helped prevent the A83 from being closed by up to two days as a result of the landslip, successfully avoiding disruption to road users.
Geotechnical engineers have assessed the landslip along with teams from BEAR Scotland for safety with plans now underway to remove the debris from behind the bund. Short-term lane closures will be in place while teams mobilise plant and heavy machinery to remove the material from the bund.
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The rock-bunds form a barrier on the hillside parallel to the A83, and mean that material from a potential landslip is held behind the rock barrier. The 28,000 tonnes of rock used to create them was sustainably re-used during excavations of the nearby £2.24M catch-pit project at the Rest and be Thankful, where three large 'pits' were created to help provide further resilience against potential landslips in the area. The excavated rock was transported three miles to Glen Kinglas and used to construct the bunds, providing a considerable reduction in carbon emissions with teams saving an estimated 50,000 lorry miles – roughly the same distance as travelling around the world twice – due to the huge reduction in haulage distance for the excavated rock.
Heavy rain throughout the week has meant BEAR Scotland teams have been on high-alert and responding to various incidences of fallen trees and localised flooding on the north west trunk road network since the weekend.
Eddie Ross, BEAR Scotland's North West Representative said: "The bunds at Glen Kinglas have performed as designed and have been successful in preventing around 300-tonnes of landslip material from over 200m above the road reaching the carriageway and causing the road to be closed to road users.
"We're pleased that this innovative and sustainable method of landslip resilience has been effective, demonstrating that this engineering design and extensive studies of the geotechnical landscape in the area have been a success.
"Our teams have been working hard to respond to various incidences of fallen trees and reports of localised flooding on some sections of the network throughout the past few days, and we're now turning towards the debris removal operation at Glen Kinglas. This will involve some short periods of traffic management while machinery is mobilised to remove the debris from behind the bunds, and we thank all road users for their patience while this is completed."
(MH/JG)
