Project managers tend to believe their cost estimates - whether they have exceeded budgets in the past or not. It is dangerous to accept the engineering cost estimates, which are often optimistic or unrealistic. Though cost estimates incorporate contingency reserves below-the-line, these estimates of reserves often do not benefit from a rigorous assessment of risk to project costs. Risks to cost come from multiple sources including uncertain project duration, which is often ignored in cost risk analyses. In short, experience shows that cost estimating on projects is rarely successful - cost...