Views on the Actual Critical Path vs As-Built Critical Path
The 2nd edition of the SCL protocol for delay and disruption identified three ways to determine criticality or let’s say the critical path term when carrying CPM analysis, those are;
-?????????Prospective Critical Path;
-?????????Contemporaneous Critical Path; and
-?????????Retrospective Critical Path.?
Although it may be seemed that the protocol had established the definition of those ways (terms), however, it is still had created a controversy between delay analyst professionals about the use of the right term when performing or expressing the critical path analysis findings.
The protocol has associated the six commonly used methods with the above Critical Path terms as follows:
-?????????Impacted as Planned Analysis (IAP) determine the critical path ‘Prospectively’.
-?????????Time Impact Analysis (TIA), Time Slice Windows Analysis (TSA) and As-Planned vs. As-Built Windows Analysis (APABW) determine the critical path ‘Contemporaneously’.
-?????????Retrospective Longest Path Analysis and Collapsed As-Built Analysis (CABA) determine the critical path ‘Retrospectively’.
The protocol has then implied further critical path terms when describing the common used methods;
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-?????????Contemporaneous or ‘Actual’ critical path. This term has been cited only with TSA and APABW methods; and
-?????????Retrospective ‘As-Built’ critical path. This term has been cited only with the retrospective longest path analysis method.
Although the ‘Actual’ and ‘As-Built’ terms sound similar (according to the old school), however, the protocol had distinguished between both terms but not provide a clear definition. My interpretation of both terms are as follows;
-?????????Actual critical path is a dynamic path (or sometime referred to progressive path) reflect the shifting of the path into a different area of the programme over the course of time. It is fairly associated with programme updates or as-built programme sliced/divided into windows period (time slice/snapshots). This shall allow the analyst to determine the critical path from time to time and how it evolved over the course of the project.
-?????????As-Built critical path is a static path over the course of the project. The path is determined by tracing the longest continuous path backwards from the actual completion date towards actual commencement date. The path does not account for the contemporaneous effect over the course of the project. Thus it is referred to a static as-built critical path. ?
The faced controversy is due to different terms used under different guidelines (i.e. SCL protocol and AACE recommended practice) and not having a unified and complete glossary for delay analysis used terms.?
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Ferdinand Soco
Consultant Project Management
6 年In a "Contemporaneously" method i.e TSA, fundamental assumption is remaining activities are to executed according to baselined schedule logic, Hence Actual critical path is dynamic, while in "Retrospective" method analyst re-generates critical path based on past event records, hence as-built critical path is static.
FEED@EPC - Project engineering, Contract management/ EOT & Claims, Project control/ Qualitative Risks and Construction execution
6 年Interesting article and mind challenging. Comparing AsPlanned, as contractual baselibe, vs AsBuilt in terms of critical path became important the level of details to really understand delay events when happened and through proper project deliverables looking facts to avoid no sense dispute. I mean the approval cycle, contents of reviews, progress comparison plan vs as built, productivity for claimef work tasks, EP feasibility
Owner @ Fearnsides and Associates - Construction Management Services Consultants - Claims, Delay Analysis, Commercial, Contract Admin & Management, Project Controls, QS & Expert Witness(delay, quantum & support).
6 年You can do a as-planned v as-built static as-built CP through windows. The 'window" thresholds being baseline and revised updated and progressed baselines. If the updated contemporary updates have not been corrected and the update has out of sequence works and each update does not reflect a Contractor's intentions. A calculated approach to as-planned v as-built CP determination is the safest way and most reliable. A calculated approach, to the as-planned v as-built - as-built CP determination is just that calculated, no subjectivity and no impressionistic guess work.?