Rules for developing Network Diagrams

Some basic rules for developing network diagrams are:

  • Network Diagrams flow from left to right
  • An Activity cannot begin until all preceding connected activities have been completed
  • Arrows on Network Diagrams depict the precedence and flow of Activities. Arrows can cross over each other without any impact.
  • Each Activity should have a unique identification number
  • It is acceptable to leave gaps between Activity Identifiers such as: 1, 5, 10, 15. This makes it easier to add missing Activities at a later date without having to renumber the entire Network Diagram.
  • Activity Identifiers should be ascending numbers that are as simple as possible
  • Looping is not allowed
  • Conditional statements are not allowed – the network diagram is NOT a decision tree
  • Activities can only occur once on a Network Diagram. If they are to occur a second time, they should have a different name and new identifier.
  • Experience suggests that when there are multiple starts, a common start node can be used to indicate a clear project beginning on the network. Similarly, a single project end node can be used to indicate a clear ending

There are two main approaches for developing Network Diagrams:

  • AONActivity-On-Node – uses a node to depict an Activity
  • AOAActivity-On-Arrow – uses an arrow to depict an Activity
  • AON dominates most projects

One thought on “Rules for developing Network Diagrams

  1. this is right on. What do you use to create your graphics? I use’s network diagram software because it’s easy and professional, no download needed and I can work on stuff in teams from anywhere. Let me know.

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