Drawing the AON network

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Drawing the AON network

• Project Management
• (lecture)

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Elements of an AoN diagram

• Activity (node)
• Work element or task
• Name or identification of the tasks must be added
• No need for dummy (unreal) activities
• Dependency or sequence arrow
• Shows the interrelationship between activities

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Conventions

• Time flows from left to right
• Arrows direction
• Labels increase
• Head nodes always have a greater/higher label
  (letter) that of the tail node.
• A complete network has only one starting and only
  one ending event.

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Examples of activity combinations
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Graphical representation

• Representation of dependency time lags
• Activity duration times finish to start
  dependency
• Representation of milestones/deadlines (external
  constraints) Identified by an inverted triangle
  over the activity node (occasionally with an
  imposed time for the event)

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Overlapping activities

• If the activities are not fully discrete
• The second activity can start before the first is
  completed but not before it is at least partly
  completed.
• Breaking activities into components

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Interfacing

• When an activity is common to two or more
  subnetworks it is said to be an interface
  activity between those subnetworks and is
  represented by a pair of concentric circles or
  rectangles.

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Two errors in logic

• Looping underlying logic must be at fault
• Dangling an activity is undertaken with no result

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Hammock activities

• Artificial activities created for the
  representation of the overhead cost with the aim
  of cost control.
• Embrace activities belong to the same cost centre
• Zero duration time (not taking part in the time
  analysis)
• Overhead cost rate is assumed to be constant over
  the life of the hammock.

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Multiple starts and finishes

• Only used in computer programs
• All starting activities can occur at the start
  and all finish activities will occur at the end
  of the project.

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CPA, CPM and PERT

• Critical Path Analysis (CPA), Critical Path
  Method (CPM)
• deterministic with only one estimation
• Program Evaluation and Review Technique (PERT)
• probabilistic with three estimated durations

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Readings

• Lockyer Gordon (2005) Chapter 12

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Thanks for the attention!