Relative Free Floats
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Schedule a 2 activities network, not tied one to each other by precedence logic but sharing a limited resource.For example:
Activity A – 5 days
Activity B - 5 days
Both activities requiring Resource A of which only one is available.
Most software under resource leveling will schedule A and B at different time, the first one depending on your priorities selection. This is ok up to this point, but the problem is most will show float of 5 days on the first activity while a delay in this activity will delay the completion of your schedule.
Imagine that you as a Project Manager look at the "available" float as per your CPM schedule and start paying attention to those shown as critical and even start moving resources from those showing some float as to keep under control those showing no float. Because most software under resource constrained schedule will show the wrong float for resource critical activities you most probably will end up moving resources precisely from the wrong activities. You either will discover too late it was wrong or start doubting about the CPM float display. Well better start doubting about the CPM float display and either buy a glass ball or software capable of showing resource critical float.
Maybe if your software is not capable of telling you about resource critical float as long as you are conscious of this fact you can still interpret the data in useful ways, maybe it can tell you how much the activity can be delayed if you release your resource constraining, just be careful and always do what if runs before telling your people what is the true available float.
My approach would be to tell them the truth, that float as shown does not means it is available that the only way you have to verify is trough running what if, that better they don’t use any float, that if falling behind better they brainstorm with you about best recovery strategy.
Best regards,
Rafael
As far as I know, "Free Slack" tells you how much you can push an activity till it starts pushing its successors (without becoming critical).
But lets suppose you have 10 successors for that activity.
"Free Slack" will tell you how much you can delay that activity but wont tell you which is the activity affected by this delay and what happens with the other 9.
Thats a tool available in P6 and I used a lot.
Ill search this macro to see what is it about.
Thanks again!
May be I am missing the point with this thread. In MSP, tasks have
Free Slack - duration before within the activity will impact on its successor
Total Slack - duration before within the activity will impact on the completion date.
Surely it it a matter of analysing these values.
Also, do a web search, there is trace Logic macro available. This is a very usefull tool, works with MSP2002 and I think 2007.
Cheers
Hi to all.
Thanks to all for your reply.
What I mean by "deeper analysis" is the ability to take a look to all dependencies (predecessors and successors) and determine the impact that a change on any of those activities may have on other activities, how long you can delay an activity till it becomes a driver, etc.
That´s not possible in MS Project as I was told.
I was working on a 3000+ Engineering, Procurement, Construction schedule in Primavera in previous months and found those features quite useful.
Ill try Pertmaster to see if I can do something with that.
Thanks yo all!!!
Hi Jacinto,
No, the feature is not available in MS Project, only for "the one" activity as you call it.
It really pis... me of when I have to analyse programmes in depth in MS Project with respect to relative floats, driving activities, etc. so I normally end up converting those programmes into Pertmaster (now Primavera Risk Analysis) and then do it there. It has some really good features for that.
Is "relative floats" possible in P6? Havent been able to locate it there yet, but maybe I just need to look closer.
Regards,
Bo
Hi Jacinto
Welcome to Planning Planet.
I cannot help you personally because I do not use MSP.
However lots of PP members out there who will respond if they can help.
Best regards
Mike Testro
Thanks for your reply.
I`m aware of that feature of MSP 2007, but it just shows you "The One" that´s pushing the predecessor.
It doesn`t allow you to go deeper in the analysis.
I think there`s no other way, but maybe some of you would now some sort of workaround.
Thanks a lot!
If you are using MSP 2007 there is a new feature called task drivers pane and this will identify which relationship / constraint is driving. It works well when looking at an individual activity, but from recent experience this feature does not recognise when the drivers are applied at the finish of the activity.
"It doesn`t allow you to go deeper in the analysis."
Such as what?