Application of fuzzy numbers to the estimation of an ongoing project's completion time

In the paper a dynamic, interactive approach to the control of the project realization time is proposed. The duration time of the project activities is assumed to depend on certain factors, whose influence may change in time. On the basis of the project history up to a certain moment, the change in the factors influence is evaluated and the estimations of activities which have not been started yet updated. The estimations of activities and project duration time are expressed in the form of fuzzy numbers. This allows to keep a constant track of the risk of the project not keeping the deadline and to be aware which factors influence the delays, thus where to act in order to minimize the final delay while it is not too late yet – in the course of project realization, as early as possible.