New Aspects in Time-Cost Tradeoff Analysis

Abstract

This paper presents a linear programming model for solution of the time-cost tradeoff problem. Although several analytical models have been developed for time-cost optimization (TCO), many of them mainly focused on projects where the contract duration is fixed. The optimization objective is therefore restricted to identify the minimum total cost only. Another group has primarily focused on project duration minimization. The model presented here considers scheduling characteristics that were ignored in prior research. In the new formulation, variability of funding and uncertainty of project duration are considered together. A chance-constrained programming is used to incorporate the variability of funding, which is quantified by the coefficient of variation. Financial feasibility is expressed as a stochastic constraint, which is transformed into a deterministic equivalent at a prespecified confidence level. Also, project duration uncertainty is incorporated into the model by applying the program evaluation and review technique (PERT) in scheduling and then the uncertainty is quantified by the coefficient of variation at a prespecified confidence level. A system of an objective function, which is minimizing direct cost, and the group of constraints are solved using the