As part of the Western Asset Management Framework with QTS Group Ltd for Network Rail, Fairhurst was commissioned to undertake detailed geotechnical inspections of a number of earthwork assets along the POD line through the Avon Gorge. It is proposed that this freight line be re-opened for passenger transport.
Our team of engineering geologists inspected cuttings slopes at ten sites, accessing from track level and via rope access. The local geology is very varied, with strata ranging from Devonian to Triassic in age. One notable asset above a tunnel portal comprised a slope from which significant bedrock “rafts”, some of which are estimated at over 10 tonnes, were noted to be sliding towards the portal. The most significant cuttings are in Carboniferous limestone strata, which form the spectacular scenery of the Gorge.
The inspection work was primarily visual, focusing on identifying potential rock slope failure mechanisms and collection of rock discontinuity data. A Geotechnical Assessment Report was produced for each site, summarising the observations, analysing the rock slope stability hazards and presenting a qualitative risk appraisal. Each report concluded with a high-level remedial options appraisal, providing recommendations for value-engineered solutions to manage the risks.
