On-line control model for cost-simulation network projects

This paper presents a newly developed hierarchical control model for several PERT type projects being realized simultaneously. The model has two objectives: to minimize the number of control points for an on-line control at the project level, and to maximize the probability that the slowest project can meet its due date on time (company level). On-line control is carried out separately for each project in order to minimize the number of control points subject to a chance constraint, which seeks to prevent deviation from the planned trajectory. If at the control point it is anticipated that the project will not be on target subject to the chance constraint, then an emergency is called. Under emergency conditions the company level is faced with the stochastic problem of budget reassigning among the projects enabling the faster projects to help the slower ones. A numerical example is presented.