This literature review was undertaken with the objective of using previous experience to guide the preparation of a draft specification for the use of live willow poles to stabilise highway slopes. This draft specification, which is presented in Appendix A of the current report, will subsequently be applied to the establishment of site trails on the motorway network. The proposed trials are intended to verify the potential engineering benefits which may accrue through the use of live willow poles to stabilise slopes. The project is intended to focus mainly on the engineering aspects of the live willow pole technique. However, consideration is also given to the aesthetic and ecological consequences of slope stabilisation by this method. In particular, the consequences of how the method impinges on the wider requirements of the Highways Agency, to ensure integration of planting schemes within the local landscape, are discussed. A number of case histories are described in which live willow poles have been used in a variety of applications both in the UK and abroad. Potential problems which may be experienced in establishing viable plants from live poles and which may arise through the planting of a monoculture of willows are discussed. In general, the live willow pole technique appears to offer many advantages over traditional repair and palliative measures for slope stabilisation. However, before it is used widely on the highway network, it is necessary to undertake validation trials to optimise the installation process and to confirm that the method is viable. (Author/publisher)
Samenvatting