Introduction :

1. Impact-As-Planned (IAP)

• Definition: This method evaluates the impact of a disruptive event by inserting it into the as-planned schedule and analyzing the resulting modifications.
• Approach : The original schedule remains unchanged. The impact of the event is evaluated without taking into account actual progress or dynamic updates. Delays are simply added as if they had occurred exactly as planned.
• Limits : Does not take into account the progress of the project at the time of the delay. May not accurately represent the real impact if the project has already deviated from the baseline schedule.

Example: If a contractor submits a Request for Information (RFI) that takes 10 days to resolve, you insert a 10-day delay in the as-planned schedule to observe its impact on milestones.

2. Time Impact Analysis (TIA)

• Definition: A forward-looking delay analysis method that evaluates the impact of a delay on the schedule according to the actual progress of the project at the time the delay occurs.
• Approach : The disruptive event is inserted into a copy of the current schedule update (not just the reference schedule). The schedule is recalculated (forward and backward passes) to determine the impact on the completion date. Typically used in forensic delay analysis and EOT requests.
• Advantages : Provides a realistic assessment of the impact of delays on future activities. More recognized in dispute resolution and legal claims because it takes into account actual project conditions.

Example: If the project is already behind schedule due to supply problems, and a new climatic delay occurs, TIA evaluates the cumulative effect of the two delays, rather than simply adding the new delay to the baseline schedule.

Key differences

Table: IAP vs TIA

Which method to use?

• Use the’IAP to make an early assessment of potential delays before they occur.
• Use the TIA to assess the real impact of a delay in the context of contractual claims, change orders or forensic schedule analysis.

Would you like some advice on how to perform a Temporal Impact Analysis in Primavera P6?