an applicable heuristic for scheduling multi-mode resource constraint projects using pert technique in the presence of uncertain duration of activities

In the process of project planning, resource over-allocation is a major shortcoming. the resource over-allocation causes the schedules not to be applicable in practice. besides, in real projects, it is hard to predict the duration of activities since they may be changed due to lack of resources, delays in delivering resources, unskilled workers etc. that make activities not to be completed as predicted. hence, it is important to develop a method that can schedule activities by considering different execution conditions. in this research, we focused on another aspect of solving resource over-allocation problem by considering uncertain activity duration. for this purpose, a mixed integer programming model is developed where the objective function is maximizing net present value of the project while duration of activities are not deterministic. then a number of examples are solved using a heuristic algorithm. the results show that the proposed algorithm can effectively solve the case studies with no over-allocated resources. afterward, the algorithm is solved using the data of constructing a hospital. the results reveal that the algorithm can be successfully used for real projects.