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Critical Path, Float, Crashing and Fast Tracking Explained Simply
The critical path is the longest path through the schedule; its activities have zero float, so any delay on it delays the project.
In simple words
The critical path is the longest chain of tasks. If anything on it is late, the whole project is late. Tasks off that path have spare time, called float. To finish sooner, add people (costs money) or overlap tasks (adds risk).
What the PMP exam wants
The PM defines activities, sequences them, estimates durations, and builds the schedule. The approved version is the schedule baseline. Float (slack) is how long an activity can slip without delaying the project end. Critical path activities have zero float.
A near-critical path has very little float and can become critical. To shorten a schedule: crashing adds resources (costs money); fast tracking overlaps activities that were planned in sequence (adds risk).
Real example
Robot delivery (8 weeks) → installation → programming → FAT is the longest chain, so it's critical. Guard fabrication has 2 weeks of float: a 1-week delay there doesn't move FAT, but a robot arriving 1 week late does.
The common trap
A delay smaller than an activity's float does not delay the project. Adding people to an activity that isn't on the critical path doesn't shorten the project.
Remember: Critical = no cushion. Crash costs money; fast track costs risk.
🗝 Words to notice in the question
“float”, “slack”, “critical path”, “delayed X days” → compare delay with float
Try 2 practice questions
Choose an answer, or open “Show the answer.”
Question 1 An activity with 3 days of float is delayed by 2 days. What happens to the project end date?
Show the answer
Answer: C. The delay is within float, so the end date holds; 3 − 2 = 1 day of float remains, so the path is now near-critical.
Question 2 The schedule must be shortened without adding cost. Which technique fits?
Show the answer
Answer: B. Fast tracking overlaps work; it adds risk but not direct cost. Crashing adds cost.
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