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Problem of Too many FS Relations

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Wed, 2021-01-20 13:18
rauf kensuk
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Project: Typical Residence House Project   I am preparing a schedule of residence project. Construction contains 17 Blocks and each block has approx. 11 floors. So that too many activities and it s about to get 11.000 activites.    Even i don't want but i use too many "FS relationships" in order to hang the activities in timeline and I know it will cause too many Out-Of-Seqeunce ("OOS").    1st Floor >>FS>> 2nd Floor >>FS>> 3rd Floor   In practical 2nd floor may start without waiting for finishing 1st Floor and that cause "OOS"   To avoid that i m thinking to use 1st Floor >>SS and FF and + LAG: 1st Floor Duration >> 2nd Floor. If 2nd floor starts before finishing 1 st Floor, it will cause a gap as 1st Floor Remaining duration for 2nd Floor activity but not OOS, I think.    Doing SS + FF + Lag, what else may it cause a problem that I can't imagine ?  

Thanks in advance

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Replies

Mon, 2021-01-25 08:01
#1
Jerome Odeh
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Groups: Petro-Chem / Oil & Gas

Hi Rauf,

If only P6 had Soft & Hard logic features where we can identify preferential and mandatory logic relationships. Unfortunately, the gods at Oracle hardly listen to end-users so are deaf to our features requirements.

As for your schedule problem, I'd stick to FS relationshiips and change these logics to SS if a successor starts before the predecessor finishes when I enter ACTUALS. Just ensure that your Schedule Basis Memorandum makes it clear which relationships ar soft (preferential) & which ones are hard (mandatory) and update these assumptions during your regular schedule update cycle.

===

jerome odeh

https://www.plannersplace.com/

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Mon, 2021-01-25 00:58
#2
Rafael Davila
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Joined: 1 Mar 2004
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Groups: Spider Project Team

The following article might be of particular interest to users of P6 as out of the box it fails to identify many such occurrences.

Out-of-Sequence Progress

Among a few I have the following comments;

Image-121

Image-130

When is Out-of-Sequence not Out-of-Sequence? - A deeper out-of-sequence condition is demonstrated using OOS Act 3. It began as logic allows, immediately following the logical completion of OOS Act 2, so it would appear to not be out-ofsequence. An expanded view of the actual status compared with original logic shows that OOS Act 3 began prior to the finish of Act A and is thus logically out-of-sequence with Act A. No commercial software currently reports this condition as an out-of-sequence start.

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Spider does not labels activites as out-of-sequence or not out-of-sequence, it is enough to identify broken dependencies.

If OOS-3 requires some information that is prepared on activity OOS-2 and OOS-2 was finished it can be done even though activity OOS-2 was done out of sequence. lf OOS-3 started before finish of OOS-2 then the link would be broken.

Spider identifies OOS-2 as having a broken link, OOS-3 as not having a broken link, Spider delays remaining durarion of OOS-2 and OOS-3 after finish of Act-A restoring all broken dependencies still active when option to restore all broken dependencies is selected.

I wonder if P6 not being able to identify some OOS ocurrences is just a report issue or if it also means it can miss the implementation of retained logic for these ocurrences. 

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