(1) Explain your problem, don't simply post "This isn't working". What were you doing when you faced the problem? What have you tried to resolve - did you look for a solution using "Search" ? Has it happened just once or several times?
(2) It's also good to get feedback when a solution is found, return to the original post to explain how it was resolved so that more people can also use the results.
I am in the process of reviewing a schedule wherein the activities have large float. The first problem I am seeing is that the float is increasing in the successor activities. For example, the first few activities have 187 days of float, the next series 222 days, the next series 262. All of these activities are FS relationships, all using a 5 day calendar, all have zero free float. The last activity in the chain (approximately 50 activities to the chain) ties to an overall milestone for Final Completion. There is only one constraint on the schedule which is the Final Completion with a finish on or before. There are minimal SS and FF relationships. There are no lags added in the series.I am baffled as to why the activities in the front end are not showing 262 days of float similar to the tail end activities. As you follow the trail backwards, the float decreases on the front end. Schedule uses retained logic and calculated using Finish Float. I tried Start Float and float values remain the same. What am I not seeing? Has anyone seen this before? Any suggestions?
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Hi Florante,
The Planning resources tab is used in Primavera Web, there is an option of resource planning in P6Web and when you assign resources their, they reflect in Primavera Client.
Regards
Amit Parmar
Check out my blog on Primavera at http://www.primaverablog.in
The finish on or before constraint as implemented in Primavera in any case reduce the available float but does not increases it, it misled users as it can model late dates earlier than early dates, it models the impossible, is forbidden in China same as movies that talk about time travel. By looking at the stars you can see the past, but not the future.
The wrong implementation of such constraints will allow for negative float so a Dummy Owner will understand a path is critical when it is enough to display zero float. Negative float computations under resource leveling are meaningless and software that provide for resource leveling shall not compute negative float. Negative float distorts the S curves to the point where at times makes the early and late curves intersect before project finish date, a weird situation. This wrong modeling is justified by some protocols under the excuse "float is just a mathematical computation", at times even required by some specifications and encouraged by some CM and Scheduling Institutes, but they don't get it, it is wrong to model what it could have been on an active schedule. Yes I know, you cannot trust P6 computation of float but at least they should try better.
The correct implementation of such constraint shall be for it to model true schedule behavior, that the constraint will not be applied if the constraint date is not possible and the backward computations will be computed by setting the activity late dates equal to early dates, making the activity critical, displaying the critical activities under the path so a Dummy Owner can realize the job is under problems. It will allow the software to compute and display late S curves that are meaningful. In forensic analysis it is avoided and fools the computation of longest path. Because negative float is meaningless under resource leveling I wonder if this is one of the reasons why some software like MSP and P6 resource leveling is so bad.
If your software allows for the modeling of the impossible by the wrong implementation of such constraints that create negative float do not use such constraints, if you need to see criticality under such conditions then get software that correctly implement such constraints and do not allow for the creation of negative float.
Good day to everyone.
I would like to ask how to put data in item titled "planning resources" in P6. This planning resources tab contains the following:
1.0 Resources
2.0 Role ID
3.0 Roles
4.0 WBS
5.0 Committed
6.0 Start
7.0 Finsh
8.0 Life of Project
9.0 Allocated
10.0 Status Code
There is no TAB to assign in this item. Thank you very much for your help.
Regards,
RANTE
Hi Sebastian,
I noticed that you are using "finish on or before" constraint on the completion activity. When you use this particular constraint, the late dates of the activity are affected which in turn affects the total float calculations too. I would suggest that you remove the constraint and check if the Total Float calculations are still mixed up.
Regards
Amit Parmar
Check out my blog on Primavera at http://www.primaverablog.in
I think if you revised the following carefully you will rectify that:
1-Realistic and logical Durations.
2- Relationships should be logical and also logical lags.
3 Check that no open ends ,All activities have successor and predecessor except start and end
4- Check calendars carefully especially if you have more than one calendar
5-Check Constrains and p6 options like calculation tab... etc
After digging and digging throught the schedule, it boils down to the loopy logic in the schedule. The schedule contains slightly over 1,000 activities, but with close to 2,500 relationships. If you keep following the trails, you get brain drain after a while. All the suggestions were good and I'll keep them in mind for other reviews.
http://www.alphacorporation.com/49R-06.pdf
Sequential activities may be affected or activities with logical relationships on the critical path may have different float values for the following reasons:
• Date and float constraints
• Activity calendars
• Lag calendars
• Interruptible activities
• Hammock, level of effort, WBS, and other types of summary activities
• Open-ended activities
• Out-of-sequence progress
• Total float calculation method
• Resource leveling
Pay attention to Interruptible Activities, allowed under non-continuous PDM modeling. Even when this is not the most frequent cause of such behavior avoid modeling non-continuous PDM, you shall decide how many splits and how long and let resource leveling take charge.
Also look on the literature as P6 is known to have serious issues with float calculation. Also try uncheck Preserve scheduled early and late dates. A setting I do not know what is does as I am not a P6 user, someone else said it makes P6 to compute correct float values after resource leveling but still yields some wrong values, never trust float values displayed by P6, you never know for sure when there are horrors.
Best regards,
Rafael
Can't think of anything other than:
1) Does the schedule include any actual dates and if so is there any that contradict the relationships? What happens if you schedule using progress overide?
2) Any different activity types in there? eg resource dependants with a resource that is using a different calendar?
3) Do they all use the same 5 day calendar? Or do some have for example national holidays included where others do not? If all the same, is this calendar the same as the default project calendar?
Other than this, all I can advise is to find the point in the path where the total float changes, and take a good look at that relationship, and the activities at either end to see if you can find anything different.
Email: PPadmin@planningplanet.com
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