Hierarchical models for multi-project planning and scheduling

The authors propose a model-based approach to nonpreemptive multi-project management problems, based on a hierarchical two-stage decomposition of the planning and scheduling process. Two performance criteria are considered: the net present value, which includes investment costs, operating costs, revenues, penalties for late completion; and the service level, expressed as the agreement between the completion times of the different projects and the customer needs. The resulting hierarchy of integer programming models is aimed at assisting the planners in understanding the interrelations among the allocation of resources, the timing of the activities, the cash flows. A class of branch-and-bound procedures is then proposed for the solution of these integer programming models.