The Society of Construction Law's Delay and Disruption Protocol is the closest thing the industry has to a shared reference for how delay claims should be analyzed. It is not law, and it does not bind any court or tribunal on its own, but it is widely cited as best practice, and its six accepted delay analysis methods give both sides of a dispute a common vocabulary to argue within.
Choosing the wrong method for the situation does not just weaken a claim's persuasiveness, it can hand the other side an easy technical objection that has nothing to do with whether the underlying delay was real.
| Method | How it works | Best suited to |
|---|---|---|
| Impacted As-Planned | Delay events are inserted into the original baseline programme and the resulting shift is measured. | Simple projects, early-stage estimates. Often criticised as theoretical since it ignores what actually happened. |
| Time Impact Analysis (TIA) | Each delay event is inserted into a contemporaneous programme update taken at the time it occurred. | Prospective analysis, assessed close to the event, which the SCL Protocol favors over a wait-and-see approach. |
| Time Slice / Windows Analysis | The project is broken into windows, and the critical delay in each window is analyzed against the updated programme for that period. | Longer projects with many overlapping events and good periodic programme updates. |
| As-Planned vs As-Built | The original plan is compared directly against what actually happened, and the differences are explained. | Straightforward narratives where the story of what changed is clear from the record. |
| Collapsed As-Built | Employer-caused delays are removed from the as-built programme to show when the contractor would otherwise have finished. | Retrospective analysis where a detailed, reliable as-built record exists. |
| Longest Path Analysis | The actual driving path to completion is traced through the as-built programme. | Establishing which delays were genuinely critical, as opposed to merely present. |
Prospective versus retrospective: the split that matters most
The SCL Protocol has a clear preference buried in its guidance: assess extension of time claims as close as possible to the delay event, using the programme update current at that time, rather than reconstructing everything after the project finishes. A “wait and see” approach to EOT assessment is explicitly discouraged. Time Impact Analysis is built for exactly this prospective approach. Collapsed As-Built and Longest Path Analysis, by contrast, are inherently retrospective, useful once the project is complete and the full as-built record exists, but not built for assessing an extension while work is still underway.
Why the choice is rarely free
In practice, the method is often chosen for you: it depends on what records actually exist. A Time Impact Analysis needs a reliable programme update from the time of the event. A Collapsed As-Built needs a complete, accurate as-built programme. A project with strong programme updates and weak as-built records points toward one family of methods; a project with the opposite pattern points toward another. This is one more reason the record-keeping habit matters more than any single analytical technique: the method with the best reputation is useless without the data it needs to run.
How to think about method selection
- Match the method to the records you actually have, not the one that sounds most rigorous in the abstract.
- Prefer prospective methods like TIA when the project is still live; the Protocol explicitly discourages a wait-and-see approach.
- Retrospective methods like Collapsed As-Built need a genuinely reliable as-built programme to be defensible.
- The method is a tool for an expert to choose, not a default the software should silently apply on your behalf.
DraftMyEOT organizes the events, dates, and evidence every method needs. Method selection stays an expert judgment call, always.
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This article is general information about how these contract mechanisms typically work. It is not legal advice, and it is not a substitute for review of your specific contract by a qualified professional.