Flaw #6 Negative Float  (mike vergis - 02/25 13:19:57)

Flaw #6 Negative Float
Negative float probably is the most misunderstood aspect in scheduling and thus the flaw, because it becomes the most abused feature in computerized scheduling. If project managers and others would just leave the negative float alone; the schedule, itself, will over time, make the necessary course corrections to bring it back to where the schedule logic wants it to be; either ahead, on-time, or behind schedule. Knowing that a project is behind schedule should be considered as a good thing. It is certainly better than submitting a false representation of a fake reality. Making schedule adjustments on paper and accepting zero total float instead of accepting negative float reality, may make everyone warm and fuzzy for a time, but later on down the road, well, you know what happens. Stuff happens!

Construction projects are defined by the S-Curve in which construction starts out slowly, naturally accelerates as indicated in the slope of the S-Curve to gradually gain momentum, and at some cross-over point, appropriately decelerates to final completion, which describes the S shape or more characteristic, the misshapen elongation of the S shape. Note: The natural acceleration that occurs in the construction process is not a Time-Impact, but the result of more and more different resources being able to work at the same time. As the project nears completion and begins to naturally decelerate, the opposite occurs with less and less resources required to work at the same time.

Negative float in the schedule should be standard operating procedure, so, why correct it. Make the Out-of-Sequence adjustments, progress the schedule activities, and let the schedule do its job. Changing logic, durations, or calendars is self-defeating. Negative float in the schedule is sending a message, so why shoot the messenger. Take the message and do something about it other than falsifying the original logic in the schedule. Returning the schedule to zero total float is not solving the situation, it only disguises future situations. Demanding a zero float schedule may make the owners, architects, and CMs feel back-slapping happy, but every project should have, at the very least, ONE person on the job that knows what is happening and that person is the Project Scheduler.

Sometimes I would be accused of running two separate schedules for a single project, because I would accurately predict future adverse situations before anyone else even anticipated it. To this accusation I would always respond: Everyone has the same information that I had, I only use it differently.

   
   

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