How to draw an Activity Network - Worked Example

Rules of Drawing Networks

Network analysis refers to a family of related techniques developed to aid management to plan and control projects.

Network analysis is used to evaluate projects that are large and complex; where restrictions in terms of time and resources exist. 

Importance of network analysis

• At the planning stage, network analysis helps managers to plan on how to get started on the project by identifying the activities of the project.

  
  

• It helps in showing the inter-relationship of various jobs or tasks which make-up the overall project and identifying the time durations for each.

  
  

• It clearly identifies the critical parts of the project.

• Provides planning and control of information on time, cost and resource aspects of a project.

• Network analysis helps in determining the total completion time to the project if everything goes as to the plan.

Rules for drawing networks

1. A complete network should have only one point of entry – a start event and only one point of exit i.e. a finish event.

2. Every activity must have one preceding or ‘tail’ event and one succeeding or ‘head’ event. Several activities may use the same tail event and heat event.

3. No activity can start until its tail event is reached.

4. An event is not complete until all activities leading into it are complete.

5. Loops .i.e. a series of activities which lead back to the same event, are not allowed since networks are a progression of activities always moving onwards in time.

6. All activities must be tied into the network.

Other guiding conventions

• Networks proceed from left to right

• Networks are not drawn to scale i.e. the length of the arrow does not represent time elapsed.