Prospective Time Impact Analysis
A delay has occurred — how many days does the project finish late because of it? A prospective TIA answers by modelling, not estimating: insert a delay fragnet into the current schedule, recalculate the CPM, and measure the net critical movement. Built on AACE 52R-06.
What a Time Impact Analysis is
A delay has occurred (or is about to). The question the contract asks is: how many days does the project finish late because of it? A TIA answers that by modelling — not estimating — the delay's effect on the CPM.
Prospective vs. retrospective
The same fragnet logic can be applied looking forward or backward — and the timing changes the credibility.
| Prospective TIA | Retrospective analysis | |
|---|---|---|
| When | At (or near) the time of the delay | After the project, looking back |
| Schedule used | The current updated schedule's forecast | The as-built record of what happened |
| Question | How much will this delay push completion? | How much did delays push completion? |
| Strength | Contemporaneous, no hindsight; ideal for live EOT claims | Captures what actually occurred, incl. concurrency |
The TIA method in five steps
- Pick the right schedule — start from the most recent accepted, updated schedule before the delay; its data date should sit just ahead of the delay event.
- Build the delay fragnet — model the delay as real activities and logic (duration, predecessors, successors) representing exactly what the delay does to the work.
- Insert and recalculate — tie the fragnet into the network at the correct point and re-run the CPM so it recomputes all early/late dates.
- Measure the movement — compare the projected completion before and after; the difference is the delay's time impact, the candidate extension of time.
- Account for float & concurrency — if the delayed path had float, only the net critical movement counts; check whether any concurrent delay shares responsibility.
Worked example — a single prospective TIA
The current updated schedule forecasts completion on day 200. An owner-directed redesign delays a critical-path activity. The delay fragnet is 15 working days; the affected path carries 4 days of total float.
From fragnet to net extension of time
Worked example| Step | Value |
|---|---|
| Forecast completion (before) | day 200 |
| Delay fragnet duration | 15 days |
| Total float on the affected path | 4 days |
| Net critical impact = 15 − 4 | 11 days |
| Forecast completion (after) | day 211 |
The first 4 days of the delay were absorbed by float and cost no time; only the 11 days beyond float moved the completion date. Claim 11 days of EOT — not the full 15. Overstating the impact by ignoring float is a fast way to lose credibility.
TIA impact calculator
Set the delay's duration and the float on the affected path. Only the movement beyond float is a critical impact.
Net extension of time
Try it yourselfSet the delay's duration and the float on the affected path. Only the movement beyond float is a critical impact.
Ten things to remember
- A TIA models, it doesn't estimate — it inserts a fragnet and re-runs the CPM.
- Prospective TIA is contemporaneous — run on the current schedule, with no hindsight.
- Start from the right schedule — the latest accepted update before the delay.
- The movement of completion is the time impact — measure before vs after.
- Float comes off first — claim only the net critical movement, not the full delay.
- Model delays one at a time, in sequence — don't lump them together.
- Check for concurrency — a concurrent contractor delay can reduce entitlement.
- A non-critical delay moves nothing — duration alone is not impact.
- The fragnet must reflect reality — honest durations and logic, or the model is worthless.
- Run it contemporaneously — a TIA filed promptly is far stronger than one assembled years later.
Glossary
- Concurrency
- Two or more delays acting in the same period; can reduce or bar recovery.
- Data date
- The "as-of" line in a schedule update; a TIA starts from the update just before the delay.
- Extension of time
- Additional contract time granted for the net critical impact of an excusable delay.
- Fragnet
- A small network of activities and logic representing a delay or change.
- Net critical impact
- The delay movement beyond available float — the part that actually extends completion.
- Prospective analysis
- A forward-looking analysis run at the time of the delay, without hindsight.
- Time Impact Analysis
- A modelled method that inserts a delay fragnet into the current schedule to forecast its effect on completion.
- Total float
- The time a path can slip without delaying completion; absorbed before any EOT is due.