The problem with As-Built Schedules is that they don't show criticality for anything other than at time ‘Now.’ On the other hand, As-Planned Schedules show criticality and logical inferences but are not based on what actually occurred. The As-Planned/As-Built schedule is a combination of the two. It is based upon actual events and still shows criticality and may be used for analysis.
Others have tried to make As-Planned/As-Built schedules before and have come up short. They removed the actual start and finish dates and reset the As-Built Schedule to unstarted. This is referred to as "destatusing the schedule." To make the destatused As-Built schedule even more like the As-Built, they then replace the original durations of each activity with the actual durations as computed in the As-Built schedule. It is a little more work to apply the actual durations found in the As-Built schedule to the As-Planned schedule, but this has been done as well. Up to now, this is as far as an Analyst could go. The resultant schedule looks funny, as it invariably runs longer than the actual As-Built schedule.
What is wrong with this approach is the issue of 'early starts.' Most schedules are based on the linear model where most activities follow other in direct sequence. As an example, first you deliver the steel, then you erect it. We all know that quite often construction proceeds in parallel. Tasks that were planned to be in sequence become staggered when the succeeding activity 'starts early.' To extend our example, as soon as the first shipment of steel arrives, you begin to erect and continue to erect subsequent deliveries as they arrive. This is where the current state-of-the-art in destatusing As-Built Schedules fails.
If you apply actual durations to planned activities, the sum of the logic and durations will grossly exceed the total time that the project actually took. That kind of discrepancy is difficult to overlook in a Court of Law. What is needed in addition to applying actual durations is to modify the planned logic to include the actual amount of time that each activity actually started early. Then the resultant network will resemble the actual construction sequence but still retain its computed characteristics, suitable for framing or analysis.
If this is all that is needed, then why hasn't it been done before? The answer becomes obvious as soon as you try to compute all of the earliest possible starts for each relationship for one activity. When was the last time that you computed the CPM of a 1,000 activity schedule by hand? That's right! You need a computer and a special program to do this. You've always had the computer, but didn't have the special program, until now.
Schedule Analyzer Rebuilder “As-Planned/As-Built” Options automates the task of destatusing a schedule, applying the actual durations to each activity and then calculates the amount of time each activity started early in the As-Built schedule and modifies each relationship in the AS/AB schedule to model this. The entire process is automatic and quite quick. It's amazing how quick the analysis goes, considering the fact that calculating the early start for each relationship is much more complicated than computing a CPM.
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