Time-Impact Analysis (TIA)

Definition

Time-Impact Analysis (TIA) is a forward-looking schedule-delay-analysis technique used to quantify the time impact of a specific change, delay event, or claim. The method works by taking the most recently updated schedule prior to the delay event, inserting a fragnet — a fragment of network representing the delay or change — and re-running the critical-path calculation. The difference between the new completion date and the pre-event completion date is the schedule impact attributable to the event.

TIA is one of the AACE International Recommended Practice 29R-03 forensic-schedule-analysis methods, often abbreviated MIP 3.7 (Modeled, Additive, Prospective). It is the preferred method when delay claims must be evaluated at the moment they arise rather than retrospectively.

History

Time-impact analysis emerged from U.S. construction contracts in the 1980s, codified in the COE (Corps of Engineers) manual and AACE 29R-03. Its growth tracked the rise of contractual time-extension provisions that required prospective analysis at the moment of impact, rather than retrospective analysis after project completion. Modern FIDIC, NEC4, and JCT contracts all reference techniques broadly compatible with TIA.

The Method

1. Establish the un-impacted schedule. Use the most recent updated, accepted, status schedule prior to the event.
2. Identify the delay event. Define start date, expected duration, and scope.
3. Build the fragnet. A network of activities representing the delay or change, with realistic durations and proper logic.
4. Insert the fragnet into the un-impacted schedule at the appropriate logical point.
5. Re-calculate the critical path and project completion date.
6. Compare. The difference between the new and original completion dates is the time impact.
7. Document assumptions, logic, and rationale in a narrative supporting the claim.

Principles

• Use the contemporaneous schedule, not a constructed one. Inventing a baseline after the fact invites attack.
• Apply one event per analysis where possible. Multiple concurrent events tangle attribution.
• The fragnet must be realistic. Padding the fragnet to inflate the claim destroys credibility.
• Distinguish excusable from non-excusable delay. TIA quantifies time impact; entitlement is a separate legal question.
• Address concurrency explicitly. Concurrent delays caused by different parties require careful analytical treatment.

Real-World Construction Example

On a metro station project, an unforeseen archaeological discovery halted excavation in the eastern shaft for 47 days. The contractor used TIA at week 32 of execution. The contemporaneous accepted schedule showed station completion at week 78. A fragnet representing the archaeological investigation — site secured, archaeologist mobilised, monitored excavation, removal, certification — was inserted with a 47-day duration. The re-calculated completion date moved to week 84.7. Concurrent acceleration on western shaft activities recovered 1.5 weeks. Net time impact: 5.2 weeks of excusable delay. The TIA was accepted by the owner's representative within three weeks of submission, far faster than a retrospective claim would have resolved. The technique converted a potential adversarial dispute into a documented, time-stamped, evidence-based extension of time.

Real-World IT / Agile Example

A platform team facing a vendor-caused infrastructure delay used TIA at programme level. The contemporaneous programme schedule had four interdependent release waves. The vendor delay's fragnet inserted into the programme network revealed a six-week impact on wave-3, but wave-4 (running in parallel until its dependency on wave-3) absorbed three weeks. Net programme impact: three weeks. The analysis informed both the customer commitment renegotiation and the contractual claim against the vendor. The technique is industry-agnostic; only the artefacts differ.

TIA vs Other Forensic Methods

• TIA (MIP 3.7): prospective, additive — applied at the time of the event.
• As-Planned vs As-Built (MIP 3.1): retrospective comparison of two schedules.
• Impacted As-Planned (MIP 3.2): retrospective insertion into the original baseline.
• Collapsed As-Built (MIP 3.5): retrospective subtraction of delays from the as-built.
• Window Analysis (MIP 3.4): retrospective period-by-period analysis.

TIA's forward-looking nature gives it advantages: contemporaneous data, less reconstruction, faster resolution. Its weakness is that the actual delay may unfold differently from the modelled fragnet, which a retrospective method would capture.

Project Controls Perspective

Controls teams own the TIA on most modern contracts because the technique requires both contractual sophistication and schedule-tool fluency. The discipline is to run TIA promptly — within days of the event, not months — using the contemporaneous schedule and clear fragnet documentation. A monthly schedule update with formal acceptance creates the audit trail that makes TIAs defensible later.

Common Mistakes

• Using a baseline schedule instead of the contemporaneous updated schedule.
• Inflating the fragnet beyond realistic durations.
• Ignoring concurrent contractor-caused delays.
• Bundling multiple events into one TIA, losing analytical clarity.
• Confusing time impact with cost entitlement; the two require separate analysis.
• Late submission — TIA loses much of its value if filed retrospectively.
• Failing to update the schedule for subsequent events, leaving later TIAs with a stale starting point.

Expert Tips

• Run TIA within five working days of the event. Memory and data are fresh; the audit trail is clean.
• Use the most recent monthly accepted update as the baseline for analysis. Mid-month status invites argument.
• Document fragnet logic explicitly in a narrative attached to the TIA — assumptions, durations, predecessor and successor selection.
• Address concurrency honestly: where contractor-caused delay overlaps owner-caused delay, attribution rules must be defined.
• Re-run TIA as the actual delay unfolds. The original modelled impact and the actual impact may diverge.

Key Takeaways

• TIA is a forward-looking, prospective delay-analysis method that inserts a fragnet into the contemporaneous schedule.
• Time impact is the difference between the impacted and un-impacted completion dates.
• Use the most recent accepted schedule, not a constructed baseline, as the starting point.
• Run TIA within days of the event for maximum credibility.
• Time impact and cost entitlement are separate questions and require separate analysis.

Related Concepts

TIA interlocks with Delay Analysis, CPM, Baseline Schedule, Change Control, and Network Diagrams. Fragnet templates and worked TIA examples are at PMMilestone.org.