Schedule network analysis

Key Points

• Analyzes the logic of the schedule network to determine dates, float, and critical paths.
• Supports schedule optimization through compression, resource strategies, and what-if scenarios.
• May reveal multiple critical or near-critical paths that increase time risk.
• Relies on realistic durations, dependencies, calendars, and resource availability.
• Iterative technique used during planning and whenever the schedule changes.
• Results inform the schedule baseline and ongoing forecasting and risk responses.

Purpose of Analysis

To test the feasibility of the planned timeline, understand where schedule risk resides, and identify actions to meet or improve the target dates without sacrificing scope or quality. It provides evidence for setting the schedule baseline and for managing time-related risks.

Method Steps

• Map the activity network with clear predecessors, successors, and valid leads and lags.
• Verify logic quality by checking for open ends, unnecessary constraints, and circular links.
• Run forward and backward passes to calculate early and late dates and total and free float.
• Identify critical path(s) and near-critical paths and note drivers such as long chains or hard constraints.
• Assess resource limits and run resource leveling or smoothing as needed; recalculate dates and paths.
• Conduct what-if and sensitivity analyses, including schedule compression options like crashing or fast-tracking.
• Review risks and uncertainty; adjust reserves and finalize a feasible schedule baseline candidate.

Inputs Needed

• Activity list and attributes, including dependencies, leads, and lags.
• Duration estimates and estimation assumptions.
• Project and resource calendars and availability data.
• Schedule network diagram or precedence relationships.
• Constraints and milestones from scope and stakeholder commitments.
• Risk register and uncertainty data for what-if analysis or simulation.
• Historical information and lessons learned for estimating realism.

Outputs Produced

• Calculated early and late dates, and total and free float for activities and paths.
• Identified critical path(s) and near-critical paths with associated drivers.
• Feasible finish date and milestone forecasts based on current assumptions.
• Recommended optimization actions such as compression or resource adjustments.
• Updated schedule model ready for baseline consideration and performance tracking.
• Insights on schedule risks and suggested reserves or buffers.

Interpretation Tips

• Zero total float typically indicates critical activities that drive the finish date.
• Multiple near-critical paths with low float signal higher schedule risk.
• Large amounts of float on some branches can be used to sequence work around resource limits.
• Hard constraints and excessive lags often mask logic issues and can distort float; challenge them.
• Resource leveling may change the critical path; re-run analysis after leveling.
• Use what-if scenarios to compare trade-offs before approving changes.

Example

Activities: A (3 days) starts the project. B (5 days) depends on A. C (4 days) depends on A. D (2 days) depends on B. E (3 days) depends on C and D. Path lengths are A-B-D-E = 13 days and A-C-E = 10 days, so A-B-D-E is critical.

Interpretation: B and D have zero float and must be protected. C has 3 days of total float relative to the critical path. If the team crashes B by 1 day, the finish becomes 12 days. If resources are limited and leveling delays B by 1 day, the finish slips to 14 days and the critical path must be rechecked.

Pitfalls

• Relying on fixed-date constraints instead of logical relationships, which hides true drivers.
• Ignoring resource limits, then accepting results that are not achievable in practice.
• Using optimistic durations without considering risk, leading to unrealistic end dates.
• Failing to reassess the network after compression or leveling, leaving outdated critical paths.
• Overusing lags to represent work, which reduces transparency and control.
• Not tracking near-critical paths that can quickly become critical.

PMP Example Question

During planning, the schedule shows three near-critical paths with total float of 1–2 days each. What should the project manager do next?

1. Add a fixed buffer to the project finish date to cover the risk.
2. Lock the current schedule baseline and manage variances during execution.
3. Run schedule network analysis with what-if scenarios to evaluate compression and resource options.
4. Assign overtime to activities on the longest path without further analysis.

Correct Answer: C — Run schedule network analysis with what-if scenarios to evaluate compression and resource options.

Explanation: Near-critical paths increase time risk. Analyzing scenarios helps test feasible actions and their impact before setting or changing the baseline.