PMP critical path and float: worked network and delay example

Worked network: a shorter branch has float

Original finish-to-start network with no lags, calendars or resource constraints: A takes 3 days, then splits into B (5 days) and C (2 days). D takes 4 days and starts after both B and C finish. Use elapsed-day numbering from Day 0.

A finishes at Day 3; B finishes at Day 8 and C at Day 5. D starts at the later predecessor finish, Day 8, and finishes at Day 12. A–B–D is the controlling 12-day path. C can start as late as Day 6 and finish at Day 8, so it has 3 days of total float; its free float is also 3 days in this network. A 2-day delay to C uses two days of float without changing project finish. A 4-day delay pushes D's start to Day 9 and project finish to Day 13.

Reducing C's duration alone will not shorten the original project finish. Evaluate the controlling path, other near-critical paths, cost and risk before choosing a compression action. Recalculate after any change rather than assuming the first critical path remains controlling.

Find the schedule condition first

The critical path is the longest-duration path through the current schedule network and ordinarily determines the earliest project completion. Total float indicates how much an activity may move without delaying the project finish under the stated logic and constraints.

The network result does not automatically choose the response. Crashing, fast tracking, resequencing, scope change, resource adjustment, or escalation each carries different authority, cost, quality, and risk implications.

Reliable analysis sequence

• Confirm activity durations and logical relationships.
• Complete the forward pass using the controlling predecessor at merges.
• Complete the backward pass using the controlling successor at bursts.
• Calculate total float consistently and trace the continuous controlling path.
• Evaluate response options only after considering constraints, authority, risk, and impact.

Common failure modes

Typical mistakes include selecting the shortest path, treating every near-critical activity as interchangeable, assuming a zero-float result is permanent after logic changes, or compressing the schedule before evaluating cost and risk consequences.