Unified Activity Network Model

Abstract

Activity network models are usually represented by activity‐on‐node precedence diagramming or activity‐on‐branch arrow diagramming. We present a unified model in which each activity is represented by a start node, a finish node and an intervening link. In this representation, a link can represent an activity or one of up to sixteen different precedence or window constraint types. While the problem size increases with the unified representation, the complexity of the model and solution algorithms are substantially reduced. In particular, numerous precedence and window constraint types appear as the same type of link in this model. Standard network representations and manipulations are supported directly by the model. Algorithms to perform scheduling calculations are summarized and numerical examples presented.