Assessment of site investigation and tunnel contract cost

The thesis concerns the research into the development and application of empirical guidelines regarding the capability of site investigation to define uncertainty in ground conditions and hence to minimise contract cost. The data has been abstracted from the documents of contracts on the Northumbrian Water Authority's Tyneside Sewerage Scheme and, to allow cost comparisons to be made, a system of index-linking costs has been used, which removes their time-dependency. A simplified theoretical approach, based on probability theory and decision analysis, has been included to model the situation of decision under uncertainty and comparisons are subsequently made between this approach and the empirical results. Conclusions are reached regarding the possible reduction in risk, financial uncertainty, with increasing site investigation.