Forensic Schedule Analysis
When a project finishes late and the parties disagree about why, forensic schedule analysis reconstructs the schedule history to apportion responsibility. Learn the two axes, the nine MIP methods, the workhorses, and the hardest issue — concurrency. Built on AACE 29R-03.
What forensic schedule analysis is
When a project finishes late and the parties disagree about why, someone must reconstruct the history of the schedule to apportion responsibility. That is forensic schedule analysis — done after the fact, for a claim or a dispute.
Two axes organise every method
RP 29R-03 sorts the nine methods along two fundamental questions. Get these two ideas and the whole taxonomy falls into place.
| Axis | Observational | Modelled |
|---|---|---|
| What it does | Reads delay directly from the schedules as they exist | Runs a "what-if" simulation by changing the schedule |
| Question answered | What do the contemporaneous schedules show happened? | What would have happened but for the delays? |
| Data demand | Good baseline + regular updates / as-built | A reliable CPM you can defensibly manipulate |
Within the modelled family there's a second split: additive methods insert delays into an as-planned schedule (the "impacted as-planned" idea, the same fragnet logic as a TIA), while subtractive methods remove delays from an as-built schedule to see what would have finished without them (the "collapsed as-built," or "but-for," idea).
The nine MIP methods
RP 29R-03 labels each method as a "Method Implementation Protocol" (MIP). You don't need to memorise the numbers — but you should recognise the families and the two or three workhorse methods within them.
| MIP | Family | Method |
|---|---|---|
| 3.1 | Observational · Static · Gross | As-Planned vs As-Built |
| 3.2 | Observational · Static · Periodic | As-Planned vs As-Built, period subdivided |
| 3.3 | Observational · Dynamic · Contemporaneous As-Is | Windows (contemporaneous period) analysis |
| 3.4 | Observational · Dynamic · Contemporaneous Split | Windows with split updates |
| 3.5 | Observational · Dynamic · Modified/Recreated | Windows on recreated updates |
| 3.6 | Modelled · Additive · Single Base | Impacted As-Planned (single) |
| 3.7 | Modelled · Additive · Multiple Base | Time Impact Analysis (stepped) |
| 3.8 | Modelled · Subtractive · Single Simulation | Collapsed As-Built ("but-for") |
| 3.9 | Modelled · Subtractive · Multiple Base | Collapsed As-Built, stepped |
Method explorer
Tap a method to see what it does, where it sits in the taxonomy, and what it needs.
Method explorer
ExploreTap a method to see what it does, where it sits in the taxonomy, and what it needs.
As-Planned vs As-Built
Overlay the original plan against what actually happened and measure the gap. Simple and intuitive, but it shows that the project slipped, not which delay on which path caused it — and it ignores how the critical path shifted over time. A good first picture; weak on causation.
Concurrency — when both sides are late at once
The single thorniest question in forensic analysis is concurrency: two or more delays — one the owner's, one the contractor's — operating in the same period, each independently capable of delaying completion. Concurrency typically means the contractor gets an extension of time but not prolongation money for the concurrent period: time relief, because the owner-caused delay was real; but no compensation, because the contractor would have been late anyway.
The records pick the method
As with productivity claims, you don't choose a forensic method by preference — your records choose it for you. Reliable, regularly-updated contemporaneous schedules unlock the credible dynamic methods like windows analysis. Where updates are missing or manipulated, you're pushed toward weaker modelled methods that depend on assumptions the other side will attack. The integrity of the schedule record, built during the job, is what determines how strong your forensic analysis can be years later.
Ten things to remember
- Forensic schedule analysis is retrospective — it reconstructs why a finished project ran late.
- RP 29R-03 catalogues nine methods (MIPs) so analysts share one language.
- Observational reads the schedules; modelled runs a what-if.
- Modelled splits into additive (insert delays) and subtractive (remove delays).
- Windows analysis (MIP 3.3) is widely seen as most reliable when good updates exist.
- As-planned vs as-built shows slippage, not causation — a first picture, not a proof.
- Concurrency usually means EOT but not prolongation money for the shared period.
- Method choice changes the answer — and whether concurrency is even visible.
- Your records pick the method — schedule integrity built during the job decides what's possible.
- State the MIP, show inputs, make it repeatable — transparency beats a bigger unverifiable number.
Glossary
- Collapsed As-Built
- A subtractive ("but-for") method: remove delays from the as-built to see what would have finished.
- Concurrency
- Independent owner and contractor delays in the same period; usually time relief without prolongation money.
- Forensic schedule analysis
- Retrospective study of a project's schedules to determine the cause and responsibility of delay.
- Impacted As-Planned
- An additive modelled method: insert delays into the baseline to project their effect.
- MIP
- Method Implementation Protocol — RP 29R-03's label for each of the nine recognised methods.
- Modelled method
- Runs a what-if simulation by adding or removing delays from a CPM.
- Observational method
- Reads delay directly from the contemporaneous schedules without modelling.
- Windows analysis
- A dynamic observational method that tracks the critical path period by period.