Delay & Disruption are measured relative to the Based Line Programme approved by the Engineer or Project Manager.
The process
Retrospective Delay Analysis (key points)
The process
- Analyse delays both your own, those that have been caused by the Employer and neutral delays
- Disruptions slow the progress down
- Assess these as a Percentage Production Loss over the duration of the activity
Retrospective Delay Analysis (key points)
- Correct Programme logic
- Reconcile and level critical resources
- Upgrade from Microsoft Project - you cannot use MSP for a retrospective delay analysis
- Agree Programme with Engineer (if you can)
- Impose delays into activities that they affected
- Identify concurrency
- Apply “But for” test
- Identify float usage
Types of Retrospective Delay Analysis
The collapsed as-built or but-for analysis method
This method should have the benefit of working from the full factual matrix. In order for it to work, the host schedule for the analysis should be a detailed and accurate as built schedule. The as built method has no programming logic, that is where activity relationships are linked. The method is based on the facts but the conclusion generated by the analysis is a hypothesis and not a fact. Once the result is generated, being the hypothesis, one must now spend time reviewing the hypothesis.
As-planned versus as-built windows analysis method:
This method is “retrospective” and “static”. The focus of the as-planned method is to establish the incidence, extent and causes of actual delay to completion and operates on the principle that actual delay to completion must by definition be found on the actual critical path of the project. The as-planned method therefore seeks to first locate and identify the project’s actual critical path, and only then the causes of delay.
The Impacted as-planned method:
This method of assessing a delay is to establish the hypothetical impact of the delay events on the baseline schedule. It is a “prospective” analysis method which means that it refers to the future and seeks to determine the likely impact of a particular event(s) on project completion. The contractor superimposes the delay events into the baseline schedule, links them in an appropriate manner and recalculates the schedule. The resultant impact of the events shown on the completion date is then said to be the critical delay impact.
The time impact analysis method:
This method of analysing a delay is recommended by the Society of Construction Law Delay and Disruption Protocol.
The “networked” baseline schedule is first updated with progress to a point in time just before the delay event arose.
This means that it takes account of the effect of progress and timing of delay events on the works.
This method should have the benefit of working from the full factual matrix. In order for it to work, the host schedule for the analysis should be a detailed and accurate as built schedule. The as built method has no programming logic, that is where activity relationships are linked. The method is based on the facts but the conclusion generated by the analysis is a hypothesis and not a fact. Once the result is generated, being the hypothesis, one must now spend time reviewing the hypothesis.
As-planned versus as-built windows analysis method:
This method is “retrospective” and “static”. The focus of the as-planned method is to establish the incidence, extent and causes of actual delay to completion and operates on the principle that actual delay to completion must by definition be found on the actual critical path of the project. The as-planned method therefore seeks to first locate and identify the project’s actual critical path, and only then the causes of delay.
The Impacted as-planned method:
This method of assessing a delay is to establish the hypothetical impact of the delay events on the baseline schedule. It is a “prospective” analysis method which means that it refers to the future and seeks to determine the likely impact of a particular event(s) on project completion. The contractor superimposes the delay events into the baseline schedule, links them in an appropriate manner and recalculates the schedule. The resultant impact of the events shown on the completion date is then said to be the critical delay impact.
The time impact analysis method:
This method of analysing a delay is recommended by the Society of Construction Law Delay and Disruption Protocol.
The “networked” baseline schedule is first updated with progress to a point in time just before the delay event arose.
This means that it takes account of the effect of progress and timing of delay events on the works.
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