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Will having SS & FF ties in addition to a FS tie cause inaccurate measurement of float?

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John Reeves
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Will having SS & FF ties in addition to a FS tie cause inaccurate measurement of float?  If you hit the tie button multiple times it adds those.  Because the FS tie will always make the longest path wouldn't the SS FF float not effect the float calc number because only the driving relationship would?  The only time it might make a difference might be in large schedules where progess happens out of order and in those cases that logic is more applicable, basically a safety net.  I normally don't clean them out because it is a waste of time but someone suggested it causes a float error - which I don't ever recall noticing.  How does it cause an error?  This is related to the reason that progress over-ride is superior than retained logic (because on large projects or busy environents cleaning up dead logic is largely a waste of time), but that is a debate for another day - depending on how exact the project has to be.

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Zoltan Palffy
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Joined: 13 Jul 2009
Posts: 1976

You will get an argument about the redundat logic especially from the government.

I totally disagree 100% with using progress override I can show you examples where this is absoulty non sense and the float values are incorrect. If you stay on top of out of sequence progress from the begining of the project you wil not run into your proposed problem. 

Using progress override has the electrical in-wall AND the Drywall finishing prior to the Studs which is PHYSICALLY IMPOSSIBLE.

So like Rocky says nah I don't use it 

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John Reeves
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I meant have a FS in ADDITION to compound or combination relationship.  Yes, it is a bit redundant and they commonly are by accident of hitting the chain button too many times.  But it is a common complaint with my schedules but my philosophy is that it doesn't hurt on change anything.  The arguement saying that it does hurt states that is changes the float, but I dis-agree because the FS is still driving.  In fact, and I think Ron Winter has stated similarly, it does not hurt because if it does not start FS as scheduled, the chain is not broken and there is FF as a safety net.  

Related topic:

I have the philosophy that progress overide is much better than Retained logic because on big busy construction projects schedulers do not go back and correct past logic errors which can effect logic and float even though it is dead logic and most of the time should not.  I generally run a schedule with both to see if there are any such issues.  (Unless something changed in the calculating between p3 and p6)

Zoltan Palffy
User offline. Last seen 3 hours 13 min ago. Offline
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this is called a compound or combination relationship and is used all of the time as standard practice that ties down the start of the activity as well as the finish of it. Technically an activity with only a SS successor as a relationship will be counted as an open end relationship. 

John Reeves
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Joined: 10 May 2013
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clarification: (SS 0 and FF 0 of course)