# What are the different types of network diagram?

Posted by ArticlesMaint on 9/30/2009 | Category: Project Management Interview questions | Views: 25662

There are two types of diagrams: -

• Activity on Arrow diagram ( Arrow diagram )
• Activity on Node diagram ( Precedence diagram )

AOA (Activity on Arrow) diagram
Before we understand what AOA is, let’s consider the table below which has list of
activities to start a computer institute. It has five columns below is description about the
same:
• First column is just a sequence number for the activity.
• Second column is a short activity description,
• Third column has number of days needed to complete the activity.
• Fourth column describes which activity needs to be completed to start this activity
• Fifth column shows what the final output of the activity is.

 Activity No Activity Description Duration(Days) Pre-requisite Finished Activity 0 Start project START START START 1 Decide a location 5 days 0 Location Fixed 2 Sign the lease 1 day 1 Agreement Signed 3 Paint Interior 3 days 2 Interior Ready 4 Fix Furniture 20 3 Institute finished 5 Get Faculties 6 days 0 Recruitment done 6 Prepare Course Material 10 days 8 Course designed 7 Buy Computers 2 days 5 Computer bought 8 Install Software 1 day 7 Software Installed 9 Advertise 2 days 3 Ad displayed in news paper 10 Enroll Students 1 days 9 Student enrolled 11 Start Batch END END END

Table: - Computer institute Activity list

Figure: - AOA

As the name suggests Activity on Arrow (i.e. AOA) which means arrows represent activity and the nodes represent finished activities. Figure ‘AOA’ represents how the activity is shown on the arrow and how the node shows the finished activity. So the node represents completed activities and arrows represent activities.

So let’s join the activities and nodes defined in table ‘Computer Institute Activity List’. Figure ‘AOA for Computer Institute’ shows how the AOA diagram is built. We have put
the activities on the arrow and the nodes represent the finished activity. On the arrow
itself we have put the number of days for every activity.

Figure: -AOA for Computer Institute

AON (Activity on Node) diagram

Figure: - AON

In AOA we view Activity on arrow while in AON we view Activity on the Node. So
the change of thinking shifts from viewing activities as events (AON) rather than
activities happening between milestones.

Figure ‘AON’ represents the same in a pictorial manner. Below is the same redrawn AON diagram for the computer institute activity.

Figure: - AON for Computer Institute

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