Engineers are to drill 25m boreholes as part of their inspection. Once the drilling samples have been analysed, an assessment on the stability of the hillside is expected by the end of next month.
Among the solutions being considered is to extend the tunnel. Stabilising the hillside using a technique called soil nailing – if the ground is found to be suitable – is also being considered.
The tunnel had been closed since 7 July 2012 when a landslip was caused by heavy overnight rain. Crews who were sent to investigate the collapse of the tunnel in mid-July discovered a vehicle buried under earth and mud. Two people were found dead in a car buried under 700t of mud at a road tunnel entrance.
