Delay Analysis

Definition

Delay Analysis is the structured evaluation of schedule changes to determine the cause, impact, criticality, and responsibility for delay. It supports contractual time-extension claims, prolongation cost recovery, and dispute resolution. In practice, it is the bridge between what the baseline schedule promised and what the as-built record actually delivered. Foundational terminology is catalogued in the PMMilestone PM Glossary.

History

Delay analysis as a formal discipline emerged from U.S. federal construction disputes in the 1970s and was codified internationally by the Society of Construction Law's Delay and Disruption Protocol (1st ed. 2002, 2nd ed. 2017) and AACE International Recommended Practice 29R-03. The technique was further refined by the U.K. Technology and Construction Court and by ICC arbitral tribunals handling international EPC disputes. The Project Controls Academy tracks this evolution in its forensic scheduling module.

Principles & Methods

AACE RP 29R-03 codifies five principal Methods of Implementation (MIPs):

• As-Planned vs As-Built (MIP 3.1) — visual comparison of baseline against actuals.
• Impacted As-Planned (MIP 3.6) — insert delay events into the baseline and recompute the critical path.
• Collapsed As-Built (MIP 3.7) — remove delay events from the as-built and recompute.
• Time-Impact Analysis (MIP 3.7) — model each delay prospectively at the time it occurred.
• Windows Analysis (MIP 3.4) — split the project into time windows and analyse contemporaneously.

Real-World Construction Example

On a metro station fit-out, the contractor encountered an unforeseen utility duct three weeks into excavation. Using a Windows Analysis, the project controls team isolated three reporting windows — pre-discovery, redesign, and revised execution. They re-statused the schedule at the close of each window using P6 update files, ran CPM recalculation, and demonstrated 42 working days of compensable delay on the critical path. The owner accepted 38 days; the remaining 4 were absorbed by concurrent contractor-caused rebar delivery slip — a textbook concurrent-delay carve-out.

IT / Agile Example

Even outside construction, the logic holds. A SaaS migration program slipped its go-live by six weeks. The PMO ran an Impacted As-Planned analysis on the program-level Gantt: late vendor API documentation drove four weeks, a security re-architecture demand drove two weeks, and a sprint-velocity dip during a reorg drove a further (concurrent) two weeks. The vendor was held accountable only for the four weeks demonstrably on the critical path.

Project Controls Perspective

Delay analysis is only as good as the contemporaneous data feeding it. The project controls organisation owns four critical inputs: a properly statused schedule updated at a fixed cadence, a delay event log linked to notices and correspondence, a daily diary or site report stream, and a complete audit trail of approved revisions. Without these, even the most defensible MIP collapses under cross-examination. Cross-check forecast positions with the EVM Calculator and validate schedule integrity with the Schedule Health Checker.

Practical Lessons Learned

• The party that maintains the better contemporaneous record almost always wins the delay debate, regardless of who was at fault.
• Concurrent delay rarely splits cleanly — expect to negotiate, not litigate, the apportionment.
• Tribunals dislike retrospective method-shopping. Pick a method that fits the data and the contract, and stick to it.
• "Float belongs to the project" only if the contract says so — read the float-ownership clause before any analysis.

Common Mistakes

• Choosing a method after the fact to support a preferred conclusion.
• Ignoring concurrent delay entirely and claiming the full slip.
• Relying solely on the baseline without considering as-built progress and intermediate updates.
• Failing to issue contractual delay notices within the required period — even a perfect analysis loses on time-bar.

Expert Tips

• Run a "dry" delay analysis at every monthly update so the team thinks in delay-event terms throughout execution, not just at the end.
• Keep the baseline schedule, every update, and every revised baseline under version control. Tribunals ask for them in order.
• When budgets allow, bring in an independent reviewer at 30 percent progress. Fresh eyes spot data-quality issues while they are still fixable.

Key Takeaways

• Delay analysis quantifies who caused what slip, when — and underpins every time-extension claim.
• Windows and Time-Impact Analyses are the methods most often accepted by international tribunals.
• Contemporaneous records, not clever methods, decide most disputes.
• Concurrent delay treatment varies sharply by jurisdiction — get legal advice early.

Further Reading

Practitioner references on forensic scheduling are listed in the PMMilestone Books & Publications catalogue, curated by the PMMilestone founder.