Multi-mode project portfolio selection and scheduling in a build-operate-transfer environment

Integrated decision-making about selecting and scheduling a project portfolio can lead to a more desirable performance. This paper considers the problem of selecting a portfolio among a set of possible projects which should be scheduled from vantage point of contractor simultaneously. Each project can be implemented in several modes, each of which has potential cash flows over the time horizon. Therefore, an NPV can be calculated for each project in a particular implementation mode. In this contribution, a structure composed of a fuzzy hybrid multi-criteria method and a fuzzy bi-objective mathematical programming model are presented to deal with quantitative and qualitative dimensions of the project portfolio selection and scheduling problem. To solve the problem, first the qualitative criteria are weighted by the fuzzy AHP, the obtained weights are applied to evaluate the projects in the fuzzy TOPSIS. Then, the fuzzy mathematical model is formulated with two objectives, including maximizing NPV of profit and portfolio score based on assumptions close to real conditions of build-operate-transfer (BOT) contract. According to the assumptions, projects have multi-period implementation and operation phases; there are a penalty and reward system to meet the deadlines. Also, the company is able to attract external capital. The fuzzy model is converted to its crisp counterpart, and then the model is solved using the augmented epsilon constraint method with the data of an Iranian company as a case-study. The results show that considering multiple modes for project implementation has better results in comparison with confining the implementation of each project to only one mode (the mode with the maximum NPV).