ABSTRACT

The costs associated with tunnel projects are related to many site specific factors and time related assumptions and are strongly dependent on production rates. Construction cost estimates for tunnel projects are typically developed during the early stages of project development and are primarily based on a design bid build project delivery method. The American Association of Costing Engineers (AACE) have developed a cost estimate classification system defining five classes that serves as an excellent set of guidelines to apply the general principles of estimating for the completion of cost estimates for construction projects and these guidelines are applicable for tunnel projects. Different methodologies are available for cost estimating including "top-down" benchmark approaches and "bottom-up" detailed approaches. While top-down benchmark approaches are considered to be applicable for the early stages of design, detailed bottom-up approaches should be adopted for the later stages during preliminary and final design.