Delay Analysis Methodologies

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Delay Analysis Methodologies

Delay Analysis Methodologies

There are numerous forensic schedule analysis methods that can be used to quantify delays that occurred during a project. The most common delay analysis methods are as follows:

Impacted As-Planned

The impacted as-planned analysis involves the insertion of delay events into a baseline or as-planned schedule to determine the hypothetical impact of such events. This method involves modifying the baseline or as-planned schedule to include new activities and logic to represent delay events. The difference between the project completion date in the impacted as-planned schedule and the original as-planned schedule quantifies the delay. This methodology is simple and does not require an as-built schedule. However, it is considered a hypothetical model as it does not rely on as-built data.

Collapsed As-Built

The collapsed as-built analysis is essentially the opposite of an impacted as-planned analysis. This method involves removing delay events from the as-built schedule to determine when the project should have been completed ‘but for’ the delay events. This methodology is easy to understand and does not require an as-planned schedule or contemporaneous schedule updates. However, it can be manipulated with the insertion of after-the fact logic ties and delay events.

As-Planned vs. As-Built

The as-planned vs. as-built analysis is a simple technique used to compare the baseline or as-planned schedule to the as-built schedule or a schedule update reflecting progress. This method compares planned start and finish dates with the actual start and finish dates of activities on the as-planned critical and near-critical paths. This identifies delayed starts, extended durations and late finishes. This method is most effective on simple projects with short durations and one clear critical path that remains consistent throughout the entire project. Its accuracy diminishes as the actual critical path deviates from the planned schedule.

Time Impact Analysis (TIA)

The time impact analysis (TIA) is a comprehensive technique used to analyze each delay event individually in chronological order to calculate its impact. This methodology quantifies each delay based on the schedule immediately before and after the delay event took place. The difference between the project completion date before and after the event determines the extent of the delay. TIA does not require an as-built schedule and is typically easy and quick to perform. This technique is widely accepted when used during the project to timely resolve delayed performance. However, it is considered a hypothetical model as it does not rely on as-built data, and it can be overwhelming to perform if there are numerous delay events.

Windows Analysis

The windows analysis is a retrospective technique that divides the total project duration into smaller periods (commonly referred to as “windows”), and quantifies the as-built critical path delays for each of these periods. This form of analysis compares the baseline or as-planned schedule’s forecasted critical path to the as-built schedule, reflecting the as-built conditions for each selected period. This method typically relies upon the schedules in their contemporaneous state of submission (“as-is”). The windows analysis is easy to calculate and understand. It identifies delays as well as acceleration quantities and considers real-time conditions and actual construction progress. However, the windows analysis is time-consuming, requires complete project records and depends on a reliable baseline or as-planned schedule and as-built performance information.


The appropriate selection of a delay analysis method is important to accurately quantify delays. Analysts must be aware of the strengths and limitations of each method to determine which one is most suitable for the case at hand. Several factors must be considered when selecting a delay analysis methodology including, but not limited to, contractual requirements, source data availability, budget, and time allowed for the analysis and size of the dispute.