Work to evaluate the effectiveness of innovative geotechnical repair techniques for slopes has been commissioned by Highways England. The techniques evaluated are the planting of live willow poles, Fibre Reinforced soil (FRS) and Electrokinetic Geosynthetics (EKG). These techniques were used in place of conventional slope stabilisation approaches in order to reduce the overall impact of various challenges including environmental constraints (habitat and visual), access and utility constraints, and the need to reduce the scale and/or cost of traffic management and traffic delays.

The effectiveness of each technique has been assessed, in separate reports, on the basis of trials conducted over the last 20 years. In this report the generic lessons regarding the planning, design and execution of such trials are brought together. These generic lessons have been derived from the detailed assessment of 12 trials and practical applications of the innovative repair techniques.

This information provides guidance for future Highways England trials of innovative geotechnical repair techniques. This guidance covers the purpose of the trial, site selection (including interaction with other works), location and access, verification and monitoring, and maintenance of the trial. The aim is to ensure that future trials of such innovative techniques produce clear and tangible documented evidence of their success, or otherwise.

Issues that are addressed include ensuring that the location is precisely defined along with safe access and egress; that the duration of the monitoring programme is sufficient to truly evaluate the effectiveness of processes, such as slope movement, that can be on a decadal scale; and that the verification and monitoring is relevant to the evaluation of the geotechnical processes that are important to the trial.

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