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P6.2 Strange Total Float values for Group/Sort Summary Bars

4 replies [Last post]
Fri, 2011-10-07 02:09
Nick Johnson-Pond
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Joined: 10 Mar 2010
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This is a great resource you are putting together here. I'm hoping someone can give me a bit of insight into an issue with P6.2 I'm currently having.

I'm attempting to analyse a series of very large schedules and have used the multiple float path scheduler to help me identify the near critical paths. When I Group/Sort the activities by "Float Path" however, the summary rows in the activity table are returning some values for Total Float that I do not understand.

I have for example in my 1st near critical path a short chain of 4 activities, each with a Total Float of 5 hours. I would have expected the Summary to have displayed the minimum value of the set of Total Floats, however it is instead displaying 0 hours Total Float.

Similarly in my 2nd nearest critical path I have 6 activities, each with a TF of 14h. Yet the summary displays 10h.

I'm unfortunately going to have to explain these values and the calculations behind them to management and I'm at a bit of a loss as to what is going on.

This schedule does use an unfortunate number of calendars which I understand P6 does not cope very well with, however I'm not clear on how this would result in the figures I am seeing.

Help! :)

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Replies

Wed, 2011-10-12 23:11
#1
Nick Johnson-Pond
User offline. Last seen 6 years 29 weeks ago. Offline
Joined: 10 Mar 2010
Posts: 11
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Hi Arend,

Thanks for the Tip.

I have both P6 manuals and several years worth of accumulated documentation, yet none of it seems to have very much to say regarding this issue (or the subject of my other post). There could well be an entry in the online help function I haven't uncovered, but if so I must be using the wrong search phrases.

In my experience much of the official documentation provides at best an overview of the functionality available in P6 but is very light on specifics. For more detailed information, the best resources I have found are the assorted white papers and aging forum discussions scattered around the net.

I am quite glad to see that PP has created this resource for planners to pool resources and share knowledge.

Regards,

Nick JP

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Wed, 2011-10-12 13:45
#2
Arend Woltjer
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Joined: 26 Sep 2011
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Hi Nick JP,

 

Just a tip:

You could find a Primavera manual on the net, that would clarify a lot of your questions

The help function in P6 if quite good also by the way.

Regards,

 

Arend

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Wed, 2011-10-12 04:54
#3
Nick Johnson-Pond
User offline. Last seen 6 years 29 weeks ago. Offline
Joined: 10 Mar 2010
Posts: 11
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Baris,

Thank you for the very clear explanation. I am now in a position to explain why the Summary Float's are as they are, it would seem that they are not going to be of any value analysing this schedule which uses many, many calendars. 

This seems to be a strangely counter-intuitive thing for the software to do. I cannot think of a scenario in which the described summary calculation would be a useful metric. Can you?

Again, thank you for your help.

Regards

Nick JP

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Fri, 2011-10-07 04:25
#4
Baris Hazar
User offline. Last seen 7 years 51 weeks ago. Offline
Joined: 4 Dec 2009
Posts: 39
Groups: Civil Engineering

 

Dear Nick,

I want to highlight some points that might help you:

1- Duration parameters such as OD, Total Float etc. on the summary bars are calculated by using the global calendar. I mean, since the dates on the summary bars depend only on the sub activities, duration parameters on the summary bars are not the driving parameters but the calculated parameters.

2- P6 calculates the total float of each activity depending on the total float calculation settings under scheduling options by using the activity calendar. However, during summarization of total float per each summary bar, P6 uses the date info on the summary bars and global calendar. By changing the global calendar, you will see that all the duration parameters on summary bars are changing dynamically depending the global calendar settings while leaving the date values remain intact. 

TF on Summary Bars

Let’s assume that TF= LF-EF for an activity.

EF of Summary Bar=Max{EF of Sub Activities}

LF of Summary Bar=Max{LF of Sub Activities}

TF of Summary Bar= Total Time Elapsed Between LF and EF of the Summary Bar. (Here, total time elapsed depends on the global calendar settings.)

Regards,

 

Baris

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