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Incorrect float

4 replies [Last post]
Wed, 2010-04-14 15:00
Sophia M
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Joined: 10 Mar 2010
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On the baseline schedule I am working on, I have a milestone with a constrained finish on or before 3/27/14. The Milestone is showing that it is finish on 3/7/14 however it states that there is -50 in float! Why is this happening? I’ve checked everything and I cannot find an incorrect setting!
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Replies

Fri, 2010-04-16 16:09
#1
Mike Testro
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Joined: 14 Dec 2005
Posts: 4420
Groups: Building Information Modelling, Content Moderators, GPCCAR Editors
Hi Rafael

Where did you get the idea the P6 was my favourite software?

In every thread on the subject I have declared that it is rubbish - almost as bad as MSP.

I very rarely use resource levelling and I would never - ever - attempt it in any delay analysis process.

At least with PowerProject you can select the resources to level and you get a warning when the critical path is affected - and you can undo the levelling to bring things back to reality.

Best regards

Mike Testro.
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Fri, 2010-04-16 14:40
#2
Rafael Davila
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Posts: 5241
Groups: Spider Project Team
Mike,

I just learned that under resource leveling P6 constraints the project end date and you have no other option. What you are asking is impossible within P6, even when you do not want to impose date constraints P6 will do it for you when using resource leveling.

Yes I know P6 is your favorite software, but sorry if this makes you feel sad. Look it in the positive way, it will lock your TIA under resource constraining and this you must love.

Is Asta capable of showing you, under limited resource leveling how much of a delay the model predicts due to the shortage of resources? I believe like many others it will.

Best regards,
Rafael
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Thu, 2010-04-15 06:09
#3
Rafael Davila
User offline. Last seen 18 weeks 9 hours ago. Offline
Joined: 1 Mar 2004
Posts: 5241
Groups: Spider Project Team
Check for other constraints as a constraint from another activity or the constraint on the job must finish date can create negative float on unsuspected chains. The fun starts when a path shares an activity with other paths that are also artificially constrained.

If using resource constraining then I would be suspicious of any float value displayed by P6.

http://www.planningplanet.com/forum/forum_post.asp?fid=1&Cat=1&Top=72472

Although use of negative float usually hides logic and makes it harder to understand the schedule, if required it might be convenient to the Contractor as it might have some legal implications that will allow the Contractor to claim for some additional time he would not be able to claim if not required as the rules for Negative Float Theory of Criticality might be applied.

http://www.arcadis-us-pmcm.com/assets/files/PinnacleOne_Concurrent_Delay...
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Wed, 2010-04-14 15:11
#4
Mike Testro
User offline. Last seen 29 weeks 5 days ago. Offline
Joined: 14 Dec 2005
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Groups: Building Information Modelling, Content Moderators, GPCCAR Editors
Hi Sophia

You have a constrained finish - Therefore you have a negative float.

Remove the constraint and let the software deliver the true completion date.

Never ever use constraints again.

Best regards

Mike Testro.
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