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Free Float Constraint

5 replies [Last post]
Thu, 2006-10-19 08:17
Haresh Jayanth
User offline. Last seen 7 years 17 weeks ago. Offline
Joined: 24 Aug 2006
Posts: 219
Groups: Building Information Modelling, GPC Qatar
i need a clear cut answer on this issue:

i have linked all nominated subcontractor activities accordingly

1. Date of nomination
2. Preparation of shop drawing and material submittals
3. Approval for the above
4. Lead time for material arrival at site (Here i have put free float constraint and connected to the exact commencement of activities, which i feel is the correct logic.

But our Consultant is objecting that, since they feel that any constraints should not be in the program.

Kindly advice me how do other planners connect this type of relationship if u are not using free float constraint.

And also, I want to know that, can I justify my free float constraint contractually to consultant?????

Haresh
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Replies

Thu, 2006-11-09 11:59
#1
Tahir Naseem PMP,...
User offline. Last seen 6 years 31 weeks ago. Offline
Joined: 26 Oct 2006
Posts: 85
Groups: GPC Qatar, Petro-Chem / Oil & Gas
Dear Haresh
Is it right that use of constraint in the schedule is not welcome but in some case we are compelled these. The suggestion of other guys is valuable and you can apply these in your schedule. But I think now at this stage you don’t want to revert from your points.

Yes you can write that you are right, use of free float will not affect the schedule because free float will not be greater then total float in any case. So the driven float for the activities are the total float not free float, free float is only give a cushion that you can play with the resource leveling without affecting any other activity of schedule.

This is one solution in my opinion may be correct or not.
Regards
Tahir

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Thu, 2006-11-09 05:29
#2
Haresh Jayanth
User offline. Last seen 7 years 17 weeks ago. Offline
Joined: 24 Aug 2006
Posts: 219
Groups: Building Information Modelling, GPC Qatar
Thanks Jaime,

But if I use lag , it creates problem while we are updating a program ,since we cannot keep the lag fixed as we update the program. The lag will increase / decrease depending upon the progress of the site. So keeping lag instead of free float constraint is not a wise thing to do as per my thinking.

I also know that mandatory start constraint and mandatory finish constrain are not applicable since using both the constraint we cannot calculate the correct total float while updating the program.

The question I want to ask is that
Can we prove contractually, by using free float constraint our float will not be affected.
Any suggestions to this are most welcome , since I want to write contractually to the consultant that using free float constraint in my program is correct. Pls suggests…….
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Mon, 2006-10-23 02:34
#3
Alex Wong
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Joined: 12 Feb 2003
Posts: 874
Groups: TILOS
Haresh

What you can do is using custom Data items.

Plan Start and Plan Finish. and display these in your schedule. therefore you do not need to use a constraint to the milestone or activity but still able to track some of these key days.

A lot of contract is stated you cannot use constraint because that way you can display a true Critical Path

Good Luck

Alex
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Mon, 2006-10-23 00:54
#4
Jaime Linchangco
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Joined: 16 Jul 2001
Posts: 29
Groups: None
Hi Eugene,

Good day! Free Float constraint is equivalent to "As Late As Possible" constraint. In my experience, i assigned this constraint to "Required On Site" or ROS milestone or activities for Equipment or material delivery. This is useful to determine the start of procurements (or other activities) by calculating backward from the start of its successor’s start date.

To satisfy the Consultant request, once you determined the ES of those activities with FF constraint, you could then assign a certain "lag" from its driving predecessor to simulate the same ES.

I guessed that the Consultant is not that strict with lag since they could not easily filter the activities compared with activities with constraint.

Hope this make sense.

Cheers!

Jaime
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Thu, 2006-10-19 21:27
#5
Eugene K
User offline. Last seen 13 years 50 weeks ago. Offline
Joined: 18 Oct 2006
Posts: 47
Groups: GPC Malaysia
Haresh,
if i m not mistaken, FreeFloat is the float time between a predecessor and a succesor.

so if your chain of sub-contracting activities (from Nomination to Delivery, assuming the date of nomination constraint the start of the chain) finish exactly when your construction activity should start, then with or without the Free Float, makes no difference.

correct me if i m wrong guys. dont use much of constraints in my schedule, other than contractuals keydates for STARTs and HANDOVERs.
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