Mandatory or Early constraint...

Primavera Project Planner - P3
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Nicolas Berger 👤 Member for 20 years
· Permalink

Thanks Nigel !



Actually it could mean that my sbucontractor is keeping some float in his pockets or maybe (and I think that’s the case) he’s a bit confused in his sequence of scheduling.



Thanks anyway guys for your participation !

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Nigel Winkley 👤 Member for 20 years 1 month
· Permalink

Nicolas



From your reply, it sounds like the contractor has ’forced’ his programme to meet the end date. Without the constraints, it finished earlier. This PROBABLY means that he has a lot of float that he is hiding - or making an allowance for lateness.



Done similar things but not with mandatory constraints.


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Paul Harris 👤 Member for 25 years 2 months
· Permalink

Nicolas



I would like to clarify what a Mandatory constraint does to a P3 schedule.



A Mandatory constraint stops float (negative or positive) calculating through the task with the mandatory constraint.



A Mandatory constraint in the middle of a chain will break the chain and the float calculations will start again at the constraint. Normally this is not a good practice.



Paul E Harris

Eastwood Harris Pty Ltd, Melbourne, Australia

Planning and Scheduling Training Manual & Book Publishers & Consulting

www.eh.com.au

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Nicolas Berger 👤 Member for 20 years
· Permalink

So I removed all those "Mandatory constraints"...they all had predecessors...

But result is, the sequence has changed and Finish date is 2 month earlier.



And all those milestones are now spread out.

This schedule must be rework...

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Nigel Winkley 👤 Member for 20 years 1 month
· Permalink

Nicolas



A mandatory constraint is not as flexible as an early constraint. A mandatory constraint will affect the programme logic a lot more than an early constraint.



If your contractor has used that many mandatory constraints it suggests that there is a problem with his logic and he is using the constraints to ’force’ the logic to work.



If it was me, I would make a copy, remove a section of the constraints and re-schedule. See how far out his logic is.





I generally use two mandatory constraints - Project Start and Project Finish and then only to force the float.



Cheers



Nige

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