ADM is a network diagramming technique also known as activity-on-arrow (AOA) method in which activities are represented by arrows. ADM is primarily used for scheduling activities in a project plan. In this case the key relationships between activities are represented by circles connected by one or more arrows where length of the arrow represents the duration of the relevant activity. Note, ADM only displays finish-to-start relationships, which means that each activity is completed before the successor activity starts.
In this technique, usually a dummy task is added, which represent a dependency between tasks, that does not represent any actual activity. The dummy task is added to show precedence that cannot be showed using only the actual activities. Generally, the dummy task has a completion time as 0.
The adoption of computer-based scheduling tools have reduced the use of ADM as a common project management practice. Where, the precedence diagram method (PDM), or activity-on-node, is often favored over ADM.
In the ADM network drawing technique the start and end of each node or event is connected to an arrow. The start of the arrow comes out of a node while the tip of the arrow goes into a node. Here, within the two nodes lies an arrow that represents the activity performed. The event represented by the circular node consumes neither time nor resources.
