4 Methods of Forensic Schedule Analysis Explained

When Delays Lead to Disputes

Construction delays are inevitable. When they lead to disputes over responsibility, liquidated damages, or time extensions, forensic schedule analysis provides the objective, fact-based methodology for determining what happened, who caused it, and what the impact was.

The AACE International Recommended Practice 29R-03 defines several accepted methodologies for forensic schedule analysis. Understanding when to use each method is critical for producing defensible results.

Method 1: As-Planned vs. As-Built

This is the simplest methodology. It compares the original planned schedule against what actually happened (the as-built record) to identify differences between planned and actual dates for each activity.

When to use: When detailed contemporaneous schedules are not available, or as an initial screening tool. Limitation: Does not account for concurrent delays or the effect of schedule changes during the project.

Method 2: Impacted As-Planned

This method takes the approved baseline schedule and adds delay events (fragnets) to model their theoretical impact on the completion date. The difference between the original and impacted completion dates represents the delay.

When to use: When the focus is on owner-caused delays and the baseline schedule is reliable. Often used for prospective Extension of Time requests. Limitation: Ignores actual project performance and progress, relying entirely on the planned schedule logic.

Method 3: Collapsed As-Built (But-For)

This method starts with the as-built schedule (what actually happened) and removes specific delay events to show what would have happened "but for" those delays. The difference represents the impact of the removed events.

When to use: Retrospective analysis at or near project completion. Effective for isolating the impact of specific delay events. Limitation: Requires a reliable as-built record and can be computationally complex for projects with many delay events.

Method 4: Time Impact Analysis (TIA)

The most rigorous and widely accepted methodology. TIA analyzes each delay event at the time it occurred, using the schedule status current at that point. A delay fragnet is inserted into the contemporaneous schedule to measure the impact on completion.

When to use: The gold standard for federal projects (USACE, NAVFAC, VA). Best used when contemporaneous schedule updates exist and delays need to be analyzed individually. Advantage: Most defensible methodology — accounts for actual project status and concurrent activities at the time of each delay.

Choosing the Right Method

The choice of methodology depends on available data quality, contract requirements, timing of the analysis (during or after the project), and the complexity of delay events. Federal contracts typically require or strongly prefer Time Impact Analysis. For litigation or arbitration, the most rigorous methodology supported by available data should be used.