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Afternoon everyone,
I work in Project Controls for a GC in Baton Rouge, La, and I had a question for you all. P6 is a program we use among some of our other duties and I was curious as I am still getting more and more familiar with the program. What is the purpose of Total Float and is it good to have a small amount of float in your activities?
I mainly build schedule for the Oil and Gas side and they are not very detail scheduled as we usually break them up by piping systems. However, we are getting more and more involved with P6 with our other duties so I was just curious?
Also, any good books that you all can recommend that are easy to follow to along in case I get in a jam? I have moderate knowledge of P6 and I can work my way around the program but I would like to know more of what the Program can do.
Thanks
Sincerely
Joseph
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Gary Whitehead wrote:
"Having more total float on activities is generally better, becuase it gives you more buffer in the schedule to absorb delays to activities without delaying the entire project."
Gary, I know you wrote "generally better", but I think you should add (as you probably intended!): "...all else being equal."
And all else is rarely equal. I suspect we'd agree that we would rather have a (resource-loaded) schedule where every item has zero float, and the critical path (i.e., whole project) has schedule reserve of 30D than a schedule where three-quarters of the activities have total float of 30D - 60D but the critical path has zero schedule reserve. Of course, this would be especially true if there is (as there almost always should be!) an incentive for early delivery.
I raise this issue as, unfortunately, most planners, driven by the completely artificial concept of "The Deadline!" (it is almost never a deadline -- per Andersonville Prison, where when you cross it, you are shot!), neither attempt to optimize the schedule nor know how to. That's why the Drag Cost metric is so important -- if planners could see how much money it's costing to have five activities push out the critical path by 30 days, they'd soon figure out a way to reduce the Drag (and Drag Cost) of those activities and point proudly to their value-added as schedulers.
Joseph, as far as a book is concerned, let me suggest Project Management for the Oil and Gas Industry: A World System Approach by Badiru and Osisanya. Chapter Six is "The Drag Efficient: The Missing Quantification of Time on the Critical Path." Of course, this chapter is a re-print of a 2012 Defense AT&L Magazine article of the same title, a PDF of which can be downloaded for free here. But then you wouldn't get all the other 700+ pages on PM in oil & gas industries that are in the book version.
Fraternally in project management,
Steve the Bajan
Joseph,
Total Float is the amount of time a particular activity can be delayed without it delaying the entire project.
So for a properly linked schedule, you should always have a chain of activities with zero total float (aka the critical path), which is defining when the project will finish.
Having more total float on activities is generally better, becuase it gives you more buffer in the schedule to absorb delays to activities without delaying the entire project.
Having a very large amount of total float on activities, though in principal a good thing, is often an indicator that the schedule is not properly linked together.
Cheers,
G
Email: PPadmin@planningplanet.com
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