ABSTRACT
As complete an understanding of the ground/groundwater conditions on the site of the future tunnelling works as is reasonably possible within the constraints of cost and time is a fundamental requirement in the planning of the site investigation. In areas having uncomplicated geology, or for projects where the engineering problems are not expected to be difficult to solve, sufficient information may be obtained from the preliminary site appraisal. However, in other instances a preliminary ground investigation may be required or there may be no preliminary ground investigation phase at all. A flexible approach is needed in planning and carrying out the preliminary investigation.
