Estimating and managing the costs and schedules of complex infrastructure projects has been a challenge for decades. Recent publicity on this problem has focused attention toward developing different approaches that deal more explicitly with the uncertainty that is inherent in project estimating, not just of cost but also scheduling, safety and other issues. This paper includes a review of the 70-plus year history of large infrastructure cost estimating and summaries of studies conducted around the world. This is followed by an overview of the specific methodology used in the 'Cost Estimate Validation Program' (CEVPTM) as implemented for the Washington State Department of Transportation. This risk-based cost estimation process described in this paper is a collaborative approach involving independent peer reviewers, independent experts, and project team members to validate estimates and conduct explicit assessments of financial and schedule risks and opportunities. With the potential for 'mega' civil-infrastructure projects in Toronto and Vancouver and other large transportation projects elsewhere in Canada, where significant public funds are at stake, the risk-based estimation process may be the means for owner agencies to understand the interdependent financial and technical risks early in the project. The structuring of risk-based cost and schedule estimating is described in detail and, finally, the results of applying this approach to two specific major projects are described.
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