Abstract: The hierarchical structure of the relationship between activities in the activity-on-node (AON) network diagram is difficult to be clearly displayed when there are more activities. Hence, the traditional AON network diagram is extended by introducing the scope activities (or nodes) to solve this problem. Problems of nodes’ locating and arrows line plotting between nodes in the extended network diagram are studied and an algorithm is proposed to plot network diagram. The network diagram drawn according to this algorithm can clearly show the hierarchical relationships of activities. Meanwhile, it is of simple structure and clear logical relationships by folding and expanding the scope activities.
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Key words: activity-on-node network diagram, network planning, scope activity, logical relationships