A robust multi-objective optimization model for project scheduling considering risk and sustainable development criteria

There is limited research that considers the sustainability aspect of the projects' schedule. The present study proposes a model to cover this gap by considering sustainable development criteria. A multi-objective model with four objective functions, including minimizing cost, risk, and socio-environmental impacts, has been presented to decrease the project's delay. Since some of the parameters are considered under conditions of uncertainty for the proximity of problems to real projects, the robust programming method is used to deal with the uncertainty, and the epsilon-constraint method was applied to solve the multi-objective model. Several scenarios are also defined to analyze the sensitivity of robust parameters in the generation of Pareto-based solutions, and the obtained results are also investigated. In addition, the design of experiments is applied for response surface methodology to determine the optimal levels of robust parameters that can generate solutions with greater variety. A real case study has been developed to implement different steps of the proposed model. Since the outcomes of the model determine the duration of each activity according to the objectives and different levels of robust parameters, managers and project owners can use this model as a tool to make appropriate decisions for their projects' schedules.