Prepare Activities and Dependency Logic
Start with activities that have a clear beginning, finish, owner, and output. Tasks that are too broad conceal the handoffs that control the schedule, while tiny administrative steps make the network hard to maintain. Choose enough detail to expose meaningful dependencies and decisions without turning every personal action into a scheduled activity.
For each activity, estimate working duration using the expected resources and conditions. Duration is not the same as effort: a review may require little hands-on work but occupy several working periods while feedback arrives. Document calendars, access windows, procurement lead time, and assumptions about specialist availability so the network explains why an activity spans its planned interval. Mark true milestones as decision or completion points rather than using them to hide work with unknown duration.
Connect activities according to real constraints. Ask what must be completed or started before the next task can proceed, and distinguish mandatory logic from a preferred sequence. Avoid adding links simply to make the chart look orderly. Excess logic can create an artificial critical path, while missing logic permits an impossible schedule in which dependent work appears to happen too early.
Calculate the Path and Float
A forward pass moves through the network from the planned start, using durations and dependencies to determine the earliest start and finish for each activity. Where paths join, the successor must respect the predecessor that finishes latest. The finish of the network gives the earliest project completion under the current assumptions.
A backward pass begins at that completion point and moves toward the start. It determines the latest each activity can start and finish without moving the project end. The difference between early and late timing is total float. Activities with no total float form a critical path, although a network can contain more than one path with the same controlling duration.
Float belongs to the schedule, not automatically to the team performing a task. Using it on one activity can reduce flexibility available to downstream work. Also distinguish total float from freedom that does not affect an immediate successor. Scheduling software can perform the arithmetic, but the project team must still review whether calendars, links, constraints, and progress rules make the result credible.
Use the Result to Manage Completion
Focus management attention on critical and near-critical work. Confirm that prerequisites, decisions, materials, and qualified people will be ready before those activities start. Near-critical paths deserve monitoring because a small delay or logic change can make them controlling even when the original critical chain remains on plan.
When completion needs to move earlier, test schedule compression against the network. Some activities can overlap if the team accepts added coordination and rework exposure. Others may finish sooner with different sequencing, clearer decisions, or added qualified support. Compression should target activities that actually influence the finish; shortening a task with available float may not change the project date at all.
Use path changes to frame stakeholder choices. If an approval delay moves completion, show the linked activities and the decision date rather than reporting a vague schedule concern. If recovery depends on scarce expertise, show which assignment protects the controlling work and which other commitment would move. The network turns schedule conversation into traceable cause and effect.
Update the Network as Reality Changes
Set a clear status date and update actual starts, actual finishes, remaining durations, and approved logic changes. Do not simply replace the baseline dates with current expectations. Preserving the baseline allows the team to see where the schedule moved, while the current network recalculates the path from what is now known.
Review unusual outputs before accepting them. Large float may signal a missing dependency, negative float may reflect a required date the current plan cannot meet, and a critical activity far in the future may depend on an uncertain estimate. Run sensitivity scenarios for material assumptions instead of treating a single computed finish as certainty. Keep a short record of major logic revisions so later reviews can distinguish changed facts from planning error.
Use the seat-cost planner on this page to examine the staffing and cost implications of a schedule response before committing added capacity. Pair the network with risk, resource, and milestone views because the technique does not measure quality, strategic value, or every uncertainty. Maintained carefully, it gives leaders an honest picture of timing logic and the limited set of actions that can influence completion.
The calculated path is only as reliable as the durations, calendars, dependencies, and status data entered into the network.