Float characteristics on the critical path In Critical Path Method (CPM), a critical activity’s float value is equal to what?

Civil Engineering Construction Management Difficulty: Easy
Choose an option
  • A
    maximum float
  • B
    minimum float
  • C
    zero float
  • D
    none of these
  • E

Answer

Correct Answer: zero float

Explanation

Introduction / Context:Float (or slack) measures scheduling flexibility. Activities lying on the critical path control the project duration; any delay on these activities delays the entire project. Understanding float helps managers prioritise resources and monitor risks effectively.

Given Data / Assumptions:

  • CPM network with defined earliest and latest event/activity times.
  • Critical path is the sequence with the longest total duration.
  • Critical activities are those with no scheduling leeway.

Concept / Approach:Total float = latest finish minus earliest finish (or latest start minus earliest start). For a critical activity, earliest and latest times coincide, so float = 0. This reflects that the activity must start/finish exactly as planned to avoid impacting project completion.

Step-by-Step Solution:Recognize that critical path length equals project duration.On critical activities, earliest and latest times are equal.Therefore, float = 0 for every critical activity.

Verification / Alternative check:Forward/backward pass computations in any CPM example will show float values zero on the identified critical path, confirming the rule.

Why Other Options Are Wrong:Maximum/Minimum float: Critical activities have no leeway; the float cannot be positive.None of these: Incorrect because the correct value is exactly zero.

Common Pitfalls:

  • Confusing “near-critical” (very low float) with “critical.”
  • Assuming float exists because of resource levelling; CPM float is purely time-based between earliest and latest values.

Final Answer:zero float

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