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Critical path and dummy activity significance

Short answer

The critical path is the longest continuous chain of activities from start to end; it gives the minimum project duration, and its activities have zero float, so delays there delay the whole project. A dummy is a zero-duration, zero-resource dashed arrow that maintains correct logic and unique i-j numbering but consumes no time or resource.

Define and write down the significance of critical path and dummy activities in a network diagram.

Critical path

The critical path is the longest continuous chain of activities from the start to the end of the project network; it fixes the shortest time in which the project can be completed. Activities on it have zero total float.

Significance:

  • It gives the minimum project duration.
  • Any delay in a critical activity delays the whole project, so these activities need the closest monitoring and the first call on resources.
  • To shorten the project, only critical activities should be crashed.
  • Non-critical activities have float and can be shifted to level resources.

Dummy activity

A dummy activity is a zero-duration, zero-resource activity (dashed arrow) used in the arrow diagram.

Significance:

  • It maintains the correct logical dependence between activities that cannot be shown by arrows alone.
  • It gives a unique i-j number to parallel activities.
  • It does not consume time or resource, so it does not change the duration, but it may lie on the critical path.

✓ Answer checked by Claude Opus 5.5 (high effort)

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