Time-Cost Trade-off Optimization Incorporating Accident Risks in Project Planning

Abstract

Time, cost and safety are essential elements in planning a construction project. A cost-effective project planning method is desired to reduce project cost and duration, while maintaining an acceptable safety level. Although there are many studies addressing safety management and time-cost trade-off optimization separately, less attention has been given to the effect of accident risks in tackling the time-cost trade-off problem. This research has produced a model that factors accident risks in the classic time-cost trade-off problem definition and results in an optimum solution for the time-cost-safety trade-off (TCST) problem. Critical path method is utilized to find the longest duration and the total cost of the project. Then a risk index is developed to add safety assessment to the decision-making process. Finally, the TCST problem is formulated as a nonlinear programming model. A case of a one-story building project with five what-if scenarios is presented to demonstrate and validate the proposed decision-making model using the Excel Solver. The model results show with a proper risk assessment scheme and a proper risk penalty cost setting, accident risks can be incorporated into the TCT optimization while implications of various risk management strategies can be analyzed quantitatively.