The Collapsed As-Built (CAB) analysis is a retrospective “cause and effect” methodology used to determine how delay events impacted project completion. Unlike other methodologies that build delays into a programme, CAB starts with the actual as-built schedule and progressively removes delay events to determine their impact.
- Develop As-Built Programme
If no as-built programme exists, reconstruct it using available contemporaneous records. This should accurately reflect what actually happened during the project execution.
- Insert Logic Links
Add appropriate logic links between programme activities. Ideally, these links should be based on contemporaneous documents or witness statements rather than assumptions.
- Add Delay Events
Insert identified delay events into the as-built programme and link them to the appropriate as-built activities they affected.
- Remove Delay Events Sequentially
Remove delay events (or set to zero-day duration) in reverse chronological order, starting with the latest event and working backwards.
- Reschedule and Compare
After removing each delay event, reschedule the programme to demonstrate the earlier completion date that would have occurred without that delay event.
- Measure Impact
Compare completion dates before and after each delay event removal. The difference represents the critical delay attributable to that specific event.
- Repeat Process
Continue removing delay events one by one until all have been removed, measuring the impact of each.
Advantages and Disadvantages
Advantages
- Relies upon factual as-built records
- Simple and easy to understand
- Persuasive as the estimated outcomes are based on facts
- Ideal when no baseline or an unreliable baseline programme is available
Disadvantages
- Time-consuming to produce the as-built programme
- Difficult to identify contemporaneous critical path switch points
- Only produces results when delay events are on the longest path
- Challenging to recreate logic links retrospectively
The CAB methodology is particularly useful for assessing the effect of alleged acts of negligence or breaches to determine when a project would have been completed “but for” the negligent act or breach of contract, or to determine the extent of contractor culpable delay to support an assessment of concurrency. However, depending on jurisdiction and contract terms, it may not always be appropriate for assessing Extension of Time entitlement.
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