Time Impact Analysis (TIA): A Practical Guide

What TIA is

Time Impact Analysis is a prospective delay method: it takes the programme that was current and reasonably up to date at the point a delay event arose, inserts a sub-network representing that event, and re-calculates to show the effect on the completion date. It answers “what was the likely impact of this event, judged at the time it happened?”

When to use it

TIA suits situations where you have a reliable, regularly updated baseline and can identify the event’s timing clearly — which is why the SCL Delay and Disruption Protocol favours it for prospective assessment. It is less suitable where programmes were poorly maintained or where you are reconstructing events long after the fact; there, windows or as-built methods may serve better (see what is delay analysis).

The method, step by step

1. Select the programme current at the point of the delay event, updated for actual progress.
2. Build a delay fragnet — a small logic network representing the event and its consequences.
3. Insert it at the correct point and re-calculate the schedule.
4. Read the movement in the completion date — that is the event’s prospective impact.
5. Repeat, in sequence, for each event, so impacts are assessed against an evolving programme rather than all at once.

Strengths and limitations

TIA’s strength is that it reflects what was known at the time, which courts and tribunals often prefer. Its weakness is its dependence on the quality of the programme it is applied to: a flawed baseline produces a flawed result. It also does not, by itself, resolve concurrent delay — that requires separate analysis. Applied honestly, it is a cornerstone of defensible Extension of Time assessment.

This is a general explanation of professional practice, not legal or contractual advice.