I'm reviewing various well-established methodologies for Delay Analysis on this page.

1-Impact As-Planned Method: This approach involves identifying excusable delays, where the contractor is entitled to a time extension. The extended duration is added to relevant activities, establishing a revised completion date. By calculating the days between this date and the original as-planned completion date, the analyst determines the owed days to the contractor.

2-Collapsed As-Built or “But For” Method: Here, the analyst begins with the actual as-built schedule and subtracts the duration of excusable delays owed to the contractor. This process forms the collapsed as-built schedule. The completion date on this schedule represents the hypothetical completion date if the contractor hadn’t faced delays. The days between this collapsed schedule and the actual as-built completion date signify the days owed to the contractor.

3-Time Impact Analysis: This method acts as a “Cause & Effect” analysis, simulating the impact of delay events on the planned sequence of remaining activities in an updated program of works just before these delays occurred. It analyzes the modeled impact on this updated program, delineating the “Cause” (delay event) and its subsequent “Effect.”

4- As Planned vs As-Built Comparison: This technique involves a straightforward comparison between the baseline or as-planned schedule and the as-built schedule or an updated schedule reflecting project progress. It assesses planned start and finish dates against actual start and finish dates for activities on the critical and near-critical paths. This comparison identifies delayed starts, extended durations, and late finishes. It’s particularly effective for simpler projects with concise durations and a consistent critical path throughout the project’s duration.