Relative float in P6?

Bo,

Thanks for the posting; the issue has been boggling me for days as I do not have P6 or PertMaster.

Perhaps there is a misconception as to whether the displayed value of float in the predecessor/successor table is activity float or “relative float”. I believe it is activity float and not “relative float”. In order to get these values you must run a longest path analysis every time you move from activity to activity. If your schedule is resource leveled then the computations must also take into consideration your resource constraints in the determination of “relative float” values. I don’t believe P6 and/or PerMaster can even give you true float values after resource leveling, not to mention true relative float values.

http://scheduleanalyzer.com/sa_long_theory.htm
http://www.ronwinterconsulting.com/Longest_Path_Value.pdf

The following SureTrak screen capture is displaying total float and not relative float, I don’t see a column for “relative floats” none of the values shown represent it.



If P6 and/or PertMaster can display true relative float after resource leveling it would be a surprise to my satisfaction.

Best regards,
Rafael

Hi Rafael

In Powerproject you can toggle between "before resource levelling" and "after resource leveling".

There is a distinct difference in available float for the levelled tasks.

I am not sure what you mean by "Relative Float".

Best regards

Mike Testro

Mike,

Maybe is what some call "Remaining Float", an intermediate value between float before leveling and float after leveling.

If PowerProject can display true resource critical float and path it would be great, but I still doubt it.

Try with a two activities network, of same duration and with no link in between activities, both claiming for the single available resource A.

What is the displayed available float for both activities after resource leveling? Please let me know.

Best regards,
Rafael

Ever since P6 Version 5 Multiple Float Paths option was introduced, P6 has had the ability to display early and late calculated start and finish dates. You can also show Relationship Total Float and Relationship Free Float. Refer to my paper on Understanding P6 Dates, Page 17 at http://www.ronwinterconsulting.com/published.htm.

Relative float: Say activity K has 4 predecessors: A, B, C, D and 3 successors X, Y, Z. The relative float between A and K is then how much A can be delayed before driving / delaying K, between B and K how much B can be delayed before driving / delaying K and so on for C and D. Each one of these “relative float” values for A, B, C and D to K can be different.

Say K’s predecessor A was driving another activity, J, thereby giving A a free float of zero, but at the same time A could easily have a relative float of, say 8 days, to K.

Same between K and one of its successors: The relative float for K to X is how much K can be delayed before driving / delaying X and so on for Y and Z. Again, these 3 values of relative float from K to respectively X, Y and Z can / will be different, however, K only have one value of free float, being the smallest value of the 3 relative floats.

Therefore, free float, remaining float and total float are not the same as relative float. One activity has only one value of free float or total float, but as many values of relative float as it has successors.


Best regards,

Bo

Relationship Foat is not the same as Resource Float, both are needed. I don’t know if Multiple Float Path as implemented in P6 accommodates for both or only Relationship Float, in any case is useful even if you cannot compare one against the other. I s a functionality of much value.

Resource Critical Path

Best regards,
Rafael

Ron,

Have just done a test in P6 and it appears that the "Relationship Free Float" is the value called "Relative Float" in Pertmaster/PRA.

Thanks,

Bo