A dummy activity is used to maintain the network logic and to avoid ambiguity. An activity followed by a dummy activity can only be completed once the activity or activities preceding the dummy activity is completed.
A dummy activity can be either critical or non-critical. It becomes a critical activity when the earlier start time and the latest finish time are equal. A dummy activity, being an imaginary or redundant activity, is represented by a dotted line with an arrowhead. The numbers on the terminal nodes are used to represent a dummy activity. A dummy activity is clearly explained by an example in figure As shown in the network above, A and B can be performed serially. The activities C and D can also be performed serially.
But practically, the activity D of set 2 can only be performed after completing the activity B of set 1. So a dummy line is drawn between node 2 and node 5 indicating that the activity D can only be performed after the event 2 is over. A dummy activity can be used to prevent two arrows with a common beginning and end points.
This can be explained by an example as shown in the figure When they are illustrated in a graphical format, dummy activities should be represented by the user of a dashed line with an arrow head on one end, and may in some cases be represented by a unique color. Get free Project Management updates! Related Articles:. Can a dummy arrow be a part of the critical path? NO a dummy activity cannot be part of the Critical path because its duration is zero and the purpose is for showing connection in diagramming.
Suppose that, in a particular project, it is necessary to specify a certain piece of hardware before placing an order for it and before coding the software. Before coding the software it is also necessary to specify the appropriate data structures, although clearly we do not need to wait for this to be done before the hardware is ordered.
Figure 6. We can resolve this problem by separating the two more or less independent paths and introducing a dummy activity to link the completion of data structure design to the start of the activity placing an order.
An Activity Network Diagram is a diagram of project activities that shows the sequential relationships of activities using arrows and nodes. What is the importance of dummy activity in network diagram? Dummy activities often have a zero completion time and are used to represent precedence relationships that cannot be easily if at all represented using the actual activities involved in the project.
By convention dummies are always shown as dotted arcs in network diagrams. What is Node CPM? Activity-on-node is a project management term that refers to a precedence diagramming method which uses boxes to denote schedule activities. How do you write a critical path analysis? There are six steps in the critical path method: Step 1: Specify Each Activity.
Step 4: Estimate Activity Completion Time. Step 5: Identify the Critical Path. What do you mean by Critical Path? In project management, a critical path is the sequence of project network activities which add up to the longest overall duration, regardless if that longest duration has float or not.
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