Safety interval analysis: A risk-based approach to specify low-risk quantities of uncertainties for contractor’s bid proposals

By appearing more complex projects, Design–Bid-Build (DBB) contracts could not satisfy new projects requirements and a need to new types of contracts was felt. New contracts requirements differ from previous ones. Challenging the method of proposal offering in design–construct contracts, this paper seeks solutions for more rational proposing of project uncertainties. The problem commences with the question “which duration and price a contractor must propose in a project with design–construct contract?” A part of the answer to this question is the matter of the lowest-risk limit of uncertainties which result from output of Monte Carlo Simulation and its analysis. The output of this analysis is a series of intervals named “safety Intervals” which will be contractors’ guide in offering the bid proposal.