Which delay analysis method? A guide to choosing

When a project finishes later than the contract says, the question is simple: how many days, caused by what, and whose risk were they? Answering it is not, and the method chosen shapes the result almost as much as the facts do.

The main methods

Impacted As-Planned. Delay events are added to the baseline as fragnets and the movement of the finish date is measured. Quick and cheap, but it ignores what actually happened on site.

Time Impact Analysis. Each event is inserted into the last schedule update before it occurred. The SCL Protocol prefers it for contemporaneous extension-of-time assessment because it works from the project's real status at that moment.

Windows / Time Slice Analysis. The job is divided into windows between successive updates, and the critical path and its slippage are examined in each. It needs regular, reliable updates.

As-Planned vs As-Built. The baseline is compared with what was built. Useful when no good schedule exists, but identifying the critical path leans more on judgement.

Collapsed As-Built. Delays are taken out of the as-built schedule to show when the project would have finished "but for" them. It needs a detailed as-built schedule with complete logic.

Choosing one

Five things decide the right method:

1. The contract — if it names a method, that comes first.
2. Timing — before the delay has played out (forecast) or after it (reconstruction).
3. The records — quality of the baseline, the updates, the daily reports.
4. The dispute — a handful of events, or dozens overlapping.
5. Proportionality — the cost of the analysis should fit what is at stake.

Concurrent delay

The hardest part is usually where employer and contractor delays hit the critical path at the same time. Delay layering — separating each event's effect and its sequence — is what turns a debatable number into a defensible claim.

No method is "best". The better one is the method the records can support and the other side can follow step by step.