When a delay claim reaches the review stage — whether by an owner, a claims consultant, or legal counsel — the first question is almost always about methodology. How was the delay quantified? What analysis technique was used? Is it the right one for this situation?
The choice of forensic delay methodology is not a technicality. It determines whether your analysis is accepted as credible or dismissed before anyone reads past the executive summary.
The Main Forensic Methodologies
Time Impact Analysis (TIA)
TIA is a prospective or retrospective analysis that inserts a specific delay event into the accepted baseline schedule at the point in time when the event occurred, and measures the resulting push to the completion date. It is the most widely accepted methodology by public agencies — USACE, Caltrans, Port Authority, and most state DOTs specify TIA in their scheduling specifications.
TIA works best when there is a well-developed baseline schedule with honest logic and float, and when the delay events are discrete and documentable. It loses credibility when the baseline schedule was poorly constructed or when float was artificially constrained from the start.
Windows Analysis
Windows analysis divides the project into time periods and analyzes the critical path within each window separately. It is the most rigorous methodology for complex projects with multiple concurrent delays from both parties, because it can isolate which delays were owner-caused, which were contractor-caused, and whether they were concurrent.
It requires a complete set of schedule updates and contemporaneous project records. It is time-consuming but produces the most defensible result on complicated claims.
Collapsed As-Built
The collapsed as-built methodology starts with the actual as-built schedule and removes the owner-caused delay events to show what the completion date would have been without those delays. The difference between the actual completion and the collapsed completion represents the compensable delay.
It is often used when the project is complete and a good baseline was never established, because it works backward from what actually happened. It is more vulnerable to challenge than TIA because it relies heavily on assumptions about what would have occurred absent the delay.
How to Choose
The right methodology depends on three factors: the quality of the schedule record, the nature of the delay events, and what the owner or agency will accept. If your contract specifies TIA, use TIA. If you have a complete set of updates and multiple concurrent delay events, windows analysis is the more defensible choice. If the project is complete and the schedule record is thin, collapsed as-built may be your only option — but document your assumptions carefully.
The worst outcome is choosing a methodology because it produces the largest number, rather than because it is the most appropriate for the available project record. An experienced claims reviewer will identify that immediately.
A Fourth Method Worth Knowing: Impacted As-Planned
Impacted as-planned analysis starts from the original as-planned baseline — not a contemporaneous update, and not the as-built record — and inserts delay events directly into that original logic to measure their theoretical effect on completion. It is the least data-intensive of the four AACE-recognized methodologies, since it requires only the original baseline and a list of delay events rather than a full set of periodic updates. That simplicity is also its principal weakness: because it ignores how the schedule was actually being executed and updated as the project progressed, it is the methodology most vulnerable to challenge when a complete update history exists and the other side can show the baseline itself did not reflect how work was truly sequenced. Impacted as-planned is generally reserved for situations where TIA and windows analysis are not feasible — commonly when the contemporaneous update history is incomplete or missing — because a defensible baseline is available but the periodic record needed for the more rigorous methods is not.
Why Methodology Choice Gets Challenged in Practice
Opposing experts often disagree less about the facts than about which method should apply. Reviewers typically test three things first: does the method match what the contract's scheduling specification requires, does it fit the completeness of the schedule record, and was it applied consistently rather than switched midway because another method looked more favorable. An analysis that fails any of these can be set aside before its conclusions are read. Choose the method at the outset and document why.
Whichever method applies, the underlying requirement is the same across all four: a schedule record thorough enough to support the analysis honestly. Methodology selection can optimize what is possible with the record you have, but it cannot substitute for a record that was never created. That is the argument, ultimately, for building schedules defensibly from the baseline forward rather than relying on forensic technique to reconstruct a case after the fact.
In practice, experienced forensic schedulers pick a method only after taking stock of the record: how many updates exist, how complete the logic is in each, whether cost and resource loading was maintained, and what narratives accompany each period. That inventory decides which methods are available at all. Defaulting to whatever a template or a prior project used is how otherwise sound claims end up facing avoidable challenges.