Towards a Geotechnical Input-Based Conceptual Cost Estimating Methodology for Highway Projects

Abstract

The trend in the literature reveals a wide range of innovative approaches which have been proposed to improve the accuracy of conceptual estimates. These techniques are usually based on differing analytical approaches. Although these techniques obtain estimates that closely approximate actual costs, the requisite time and resources to gather sufficient data or obtain relevant information during initial project stages may not be possible. The study proposes that for a road project whose route has been identified during planning, pending budgetary authorization, the basic geologic data that defines the subsoil conditions along the proposed route as revealed from desk studies and preliminary surveys, should be made to bear upon the pavement cost estimate developed at this point using a more deterministic base estimate costing approach. This involves using a cost prototype methodology whereby relative cost adjustment factors are computed for each segregated soil type aligning with the geologic zones, which will be used as multipliers during the preliminary costing of road works. The utility of the proposed methodology will thus be improved by the carrying out of more comprehensive and detailed engineering geological mapping of the specific region and setting up of a geotechnical database. The suggested conceptual costing approach has the potential to function as both a risk management instrument and a predictive foundation for estimating costs in diverse terrains.