The document explains the concept of an activity network diagram used in project management, detailing the relationships and sequences of project activities. It describes key terms such as activities, events, predecessor and successor activities, as well as defines dummy activities, merge events, and burst events. Additionally, it provides guidance on creating effective network diagrams and cautions against common errors.

1. Activity Network Diagram

2. • Network:
– A network is an arrow diagram denoting all the
activities of a project taking into account the
technological sequence of the activities.
– Represented by Activity –On – Arrow Diagram or
simply an Arrow diagram.

3. Project
A project is usually a one time activity with a
well defined set of desired end results.

4. Some Basic Definitions
• Activity
- Activity is a sub-task of a project
- It usually consumes resources
- An activity is represented by an arrow with a
node at the beginning and a node at the end
indicating the start and finish of the activity.

5. Some Basic Definitions
Event:
- Represented by a circle
- Start and /or finish of an activity
- Preferably called node

6. Some Basic Definitions
Predecessor Activity:
Activities that must be completed immediately prior to the
start of another activity are called predecessor activities.
Successor Activity:
Activities that cannot be started until one or more of other
activities are completed.
Concurrent or Parallel Activities:
Activities which can be accomplished concurrently are
known as concurrent or parallel activities.

7. Some Basic Definitions
Dummy Activity:
An activity which does not consume any kind of
resource but merely serves the purpose of indicating the
predecessor or successor relationship clearly in network
is called as a dummy activity.
Merge Event:
when more than one activity joins an event, such an
event is known as merge event
Burst Event:
When more than one activity leaves an event, such an
event is known as burst event
Merge and Burst Event:

8. Some Basic Definitions
• Identity Dummies
– when two or more parallel independent activities
have the same head and tail events, the identity of
the activities, as given by the event numbers, could
be lost.

9. Some Important Tips for Drawing A
Good Network
• Avoid crossing of arrows
• Use straight arrows
• Do not attempt to represent the duration of an
activity by its arrow length
• Use arrows from left to right
• Use dummies where necessary
• The network has only one entry point, called
the start event.

10. Errors in a Network
• Looping
• Dangling