Scheduling resource-constrained projects with a flexible project structure

In projects with a flexible project structure, the activities that have to be scheduled are not completely known beforehand. Instead, scheduling such a project includes the decision whether to carry out particular activities at all. This also effects precedence constraints between the finally implemented activities. However, established model formulations and solution approaches for the resource-constrained project scheduling problem (RCPSP) assume that the project structure is given in advance. In this paper, the traditional RCPSP is hence extended by a highly general model-endogenous decision on this flexible project structure. This is illustrated by the example of the aircraft turnaround process at airports. We present a genetic algorithm to solve this type of scheduling problem and evaluate it in an extensive numerical study.