In CPM scheduling, what is total float?
- Time an activity can slip without delaying project completion
- Time added to the contract period for bad weather during the job
- Time between ordering a material and its delivery to site
- Time the owner takes to review each application for payment
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A. Time an activity can slip without delaying project completion
Total float is the amount an activity can be delayed without pushing back the project finish date. Activities on the critical path have zero float. The gap between ordering and delivery is lead time.
Reference: Scheduling principles: total float
A project has four activities. A (4 days) starts first. B (6 days) and C (3 days) both follow A. D (5 days) can start only when B and C are both finished. What is the project duration?
Answer in days.
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15 days
Path A-B-D = 4 + 6 + 5 = 15 days. Path A-C-D = 4 + 3 + 5 = 12 days. The longest path governs: 15 days.
Reference: Scheduling principles: critical path calculation
An activity on the critical path takes two days longer than planned and nothing else changes. What happens to the project completion date?
- It does not change at all
- It moves two days later
- It moves one day later
- It moves two days earlier
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B. It moves two days later
Critical activities have zero float, so any delay to one passes straight through to the completion date unless later critical work is shortened. Only a delay to an activity with enough float leaves the finish date unchanged.
Reference: Scheduling principles: critical activities have zero float