In order to present the required sequence of project’s activities, they have to follow one of two available methods:
1- Precedence Diagramming Method (PDM) or Activity-on-Node (AON): it is a type of relations between activities where the basic relation is of the type of ‘Finish to Start’ where a certain activity has to be completed in order to start the next one.
2- Arrow Diagramming Method (ADM) or Activity-on-Arrow (AOA): it is similar to the AON, but activities are on the arrow of relation. Also, it is of the type of ‘Finis to Start’ relationship between activities.
Normally, AOA is much available and used by Planners who prepare basic schedule showing the basic activities and their durations.
Those diagrams are useful when preparing a basic schedule, and for finding the ‘Critical Path’ which is the ‘Red Area’ for any project where all activities have to be followed and checked.
