When designing the construction or rehabilitation of roads in unstable mountain regions subjected to floods, landslides, erosion and earthworks failures, it has become usual practice to employ a selection of the techniques described in Section 2. The need for adequate land surface evaluation in this context is obvious: (i) the information so produced is essential to many if not most design processes; and (ii) proper evaluation of topography, materials and geohazard is central to the performance of the road construction, and its maintenance in the longer term. These concepts are embodied in Fookes et al. (1985) and in Overseas Road Note 16 (Transport Research Laboratory 1997) which deals specifically with geohazards and road design in unstable mountain areas.
The selection of the techniques, and the manner in which they are applied, will depend on project area conditions, the availability of the necessary data or documents, and the nature of the engineering scheme being proposed. The techniques are usually applied in a progressive manner, with the need to refine and detail ground conditions more closely as the site selection and design procedure takes place. The conclusion to this process is the usual inevitability that final design will not be established until ground conditions are fully defined during construction.
In the case of road rehabilitation projects, existing cut slope exposures provide a more or less continuous record of soil and rock conditions above the road, while the stability of slopes and the observed distress to the existing road
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Land Surface Evaluation for Engineering Practice
This volume presents a collection of papers on techniques and case studies in land surface evaluation for engineering practice written by specialist practitioners in the field. The volume arose out of deliberations by the Second Working Party on Land Surface Evaluation set up by the Engineering Group of the Geological Society in January 1997 and chaired by Dr. J. S. Griffiths. The book examples of cost-effective methods for collecting land surface and near surface data prior to carrying further detailed ground investigations of engineering geologist, geotechnical engineers, geomorphologist and planners who have the responsibility for planning a designing investigations of potential sites of development.