FULL-TIME GEOTECHNICAL supervision by Scott Wilson resulted in flexible, accurate and effective rock face inspections on roads across the Peak District in northern England.
Peak District roads climb hills and plunge through limestone valleys streaked with waterfalls.
This means busy roads often run close to rock faces. Most of these are natural and have suffered from heavy weathering and vegetation damage.
Consultant Scott Wilson is maintaining agent for the Highways Agency's Highway Maintenance Area 14. Part of its work involves inspecting all the rock faces next to roads within the area and assessing potential risk to road users from rock falls.
Inspections began in December 2000, when Scott Wilson commissioned TRL to carry out a rapid assessment of all the faces using its Rock Slope Hazard Index (RoSHI). This revealed that 27 rock faces - some 40% in the area totalling 2.7km - needed inspecting within two years.
Faces were ranked according to the urgency of inspection needed.
Scott Wilson then carried out detailed 'tactile' face inspections using roped-access techniques and mobile elevating work platforms. Where mobile platforms were used, a two-man team inspected up to 200m a day.
Scott Wilson says full-time geotechnical supervision not only improved inspection speed and effectiveness - ensuring accurate collation of data on face geometry and condition - but the presence of a geotechnical expert with ropedaccess training allowed continuous assessment of the rock face.
It also meant inspections could be tailored for each rock face. It was possible to concentrate on areas of potential failure and - where the face was too small or fractured to allow an analysis of geometric data - to still assess the rock fall hazard.
More importantly, when the geotechnical expert judged that an area was in danger of imminent failure, action could be taken during the inspection.