Activity network diagram

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Activity network diagram
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Activity network diagram is a control tool used to establish and observe the most adequate path, also known as the critical path, and also a pragmatic agenda for the finalization of a project. The diagram is displayed graphically, describing a brief picture of all assignments, their sequence, their predicted completion time and the activities that could be completed simultaneously (Basu R, 2004, p. 129).

An activity network diagram is often referred to as:

  • Pert (project evaluation and review technique) in some alternations;
  • Cpm (critical path method);
  • a precedence diagram;
  • network analysis

Application of the activity network diagram

In the 1960s and 1970s the activity network diagram was broadly implemented in most projects. The more complex larger projects got, comprising plentiful tasks, the faster its popularity by manual methods started to decline. However, with the arrival of software systems like Ms Project and Primavera, its application at the more advanced stages of the project has increased extremely (Basu R, 2004, p. 129).

Benefits of the activity network diagram

The activity network diagram provides couple of benefits to the table. Some of them are (Basu R, 2004, p. 129).

  • The team members can envision seriousness of primary tasks in the overall realization of the project;
  • It outlines the problems of bottlenecks and unrealistic schedules;
  • It grants facilities a possibility to review and regulate both the resources and the timetables for explicit activities.

Methods of construction

To construct the activity network diagram the two methods are usually used. The activity on arrow method and the activity on node method. The most commonly used method is the latter one - activity on node. The stages of implementing the activity on arrow method described by Ron Basu as follows (Basu R, 2004, p. 129):

  1. Assemble the project team with the ownership and knowledge of key tasks.
  2. List the key tasks with brief description of each one.
  3. Identify the first task that must be done. The tasks must be done in parallel and the sequential relationship between tasks.
  4. Draw arrows for each task which are labelled between numbered nodes and estimate a realistic time for the completion of eash of these tasks.
  5. Avoid feedback loops in the diagram. Unlike Gantt charts, the length of the arrows does not have any significance.
  6. Determine the longest cumulative path as the critical path of the project.
  7. Review the activity network diagram and adjust resources and schedules if appropriate.


Author: Jakub Winiarski