Arrow Diagram Method (ADM)
This diagram depends on the definition of each activity by an arrow, as shown in Figure (4.4), and the point of connecting arrows called nodes, which are drawn as circles. This method is also called Activity on Arrow (AOA).
In Figure (4.5), activity (A) depends on activity (B). However, activity (C) depends on (B) and (D), but there is no activity line between (D) and (C). So, it put a dummy arrow (with dashed line)
with time zero to solve this situation. Dummy activities for large activities can present a problem, so the use of a precedence diagram is preferred.