Website Upgrade Incoming - we're working on a new look (and speed!) standby while we deliver the project

Tips on using this forum..

(1) Explain your problem, don't simply post "This isn't working". What were you doing when you faced the problem? What have you tried to resolve - did you look for a solution using "Search" ? Has it happened just once or several times?

(2) It's also good to get feedback when a solution is found, return to the original post to explain how it was resolved so that more people can also use the results.

Relative float in P6?

7 replies [Last post]
Fri, 2010-02-05 08:39
Bo Johnsen
User offline. Last seen 9 years 28 weeks ago. Offline
Joined: 28 Feb 2006
Posts: 119
Groups: Building Information Modelling, Civil Engineering
Lately there have been some statements in different threads / forums about the ability to see relative float for activities with more than one predecessor / successor in P6.

I often use relative floats in Pertmaster (Primavera Risk Analysis), however, so far I haven’t been able to locate it in P6. Could anybody please explain where to find it in P6, if possible.


Best regards,

Bo
Top

Replies

Fri, 2010-02-05 11:00
#1
Bo Johnsen
User offline. Last seen 9 years 28 weeks ago. Offline
Joined: 28 Feb 2006
Posts: 119
Groups: Building Information Modelling, Civil Engineering
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

Top
Fri, 2010-02-05 10:40
#2
Rafael Davila
User offline. Last seen 6 weeks 5 days ago. Offline
Joined: 1 Mar 2004
Posts: 5241
Groups: Spider Project Team
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

Top
Fri, 2010-02-05 10:37
#3
Bo Johnsen
User offline. Last seen 9 years 28 weeks ago. Offline
Joined: 28 Feb 2006
Posts: 119
Groups: Building Information Modelling, Civil Engineering
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
Top
Fri, 2010-02-05 10:27
#4
Ronald Winter
User offline. Last seen 4 years 26 weeks ago. Offline
Joined: 4 Jan 2003
Posts: 928
Groups: None
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.
Top
Fri, 2010-02-05 10:23
#5
Rafael Davila
User offline. Last seen 6 weeks 5 days ago. Offline
Joined: 1 Mar 2004
Posts: 5241
Groups: Spider Project Team
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
Top
Fri, 2010-02-05 10:05
#6
Mike Testro
User offline. Last seen 41 weeks 4 days ago. Offline
Joined: 14 Dec 2005
Posts: 4420
Groups: Building Information Modelling, Content Moderators, GPCCAR Editors
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
Top
Fri, 2010-02-05 09:47
#7
Rafael Davila
User offline. Last seen 6 weeks 5 days ago. Offline
Joined: 1 Mar 2004
Posts: 5241
Groups: Spider Project Team
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.

Relative Float

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

Best regards,
Rafael
Top