Determining the K Most Critical Paths in PERT Networks

Abstract

A fundamental problem in PERT networks is to identify a project's critical paths and its critical activities. In this paper we define the criticality index of a path as the probability that the duration of the path is greater than or equal to the duration of every other path in the network and define the criticality index of an activity as the sum of the criticality indices of the paths containing that activity. The most critical path or K most critical paths in a PERT network could be found by enumerating all the paths and calculating the corresponding criticality indices, both of which are burdensome tasks. This paper uses stochastic dominance to develop a procedure to identify the K most critical paths without using this path enumeration. The procedure has been applied to various sized PERT networks generated at random, and the results are found to be very close to those obtained by extensive Monte Carlo sampling.