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Calendar issue

9 replies [Last post]
Mia Ng
User offline. Last seen 1 week 6 days ago. Offline
Joined: 14 Jan 2008
Posts: 15

I have pulling my hairs out in the last couple of day, could not understand why this happened, can someone please help? This is an issue with the Summer working only activities (which have been assigned to the Calendar with restricted working in summer months only June, July, August and non-work in all other months).

Fixed duration is 65 days and I have been working on this programme for the last few year with no problem. It has always shown those activities from 28 June to 31 Aug (same year) in the baseline, FF relation ship with the construction activity (as predecessor) which finished in November same year. However, in the current forecast, with nothing changed to the duration or logic or calendar, the start date is 28 June but end date is now 1 June the next year (the predeccessor activivities stayed the same, i.e. still complete in Nov same year). I have tried every test I could, such as decrease duration, extend working period on the calendar etc, but it did not work.

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outage_issue.jpg

 

Hopefully someone knows what is the issue here? Many thanks

Replies

Rafael Davila
User offline. Last seen 1 hour 38 min ago. Offline
Joined: 1 Mar 2004
Posts: 4978

Consider deleting FF+lag link and replace with a new FS successor activity with no lag and duration equal to remaining lag, link this new activity FF with no lag to original successor.  No need for cumbersome fix to performance archive and you will get better visibility when the software does not help. Finish dates for lag activity will be transparent.

Image-100

I usually limit lag to model overlapped activities with SS & FF links and same lag values and use activities to model long duration lag that might need future adjustments.  Prohibiting lags can create problems with overlapping activities.  Use lags to model waiting time whenever their use create better model, use activities to model waiting time when their use make better models.

Rafael Davila
User offline. Last seen 1 hour 38 min ago. Offline
Joined: 1 Mar 2004
Posts: 4978

Links with 0 Free Float are driving and links with 0 Total Float are critical, if the software miss them then there is a bug.  I would not be surprised if software that mess with late dates to get negative float show weird values such as Free Float values greater than Total Float.

Relationship Float, and viewing in Primavera P6

If activity float calculations are unreliable I expect relationship float values to be unreliable.

P6-FF-greater-than-TF-weird-case

A1020 is critical but shows free float, weird, very weird ... under positive float having free float higher than total float is weird, very weird.

Negative float is still a poor implementation of date constraints, with good implementation of these constraints there is no need to create negative float to show criticality. Some software do not apply unachievable constraint late dates and set late dates equal to early dates as soon as this happens, showing criticality while not breaking the rules of time, late cannot be earlier than early. Back to the future is a movie, it is not real life.

Zoltan Palffy
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Joined: 13 Jul 2009
Posts: 2842
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there is a predcessor that is pushing the completion of this work into the NEXT summer period.

The work can start in June 2026 but can not finish until June 2029

in the predcessor window add a column for driving, critical, start and finish

in the data area add a colund for the calendar name

filter for all of these activities with this calendar 

go to the activity with the least amount of float on it in this filter 

then look at the predcessor window and look at the predcessor that has both driving and critical box checked

or just driving if it is not critical

then look at the finish date of that predcessor click on it and at the bottom select GOTO

now look at the calendar for that driving activity is it the same ? is it in the summer calendar 

keep doing this until you find the culpert driving the schedule into 2029 

Rafael Davila
User offline. Last seen 1 hour 38 min ago. Offline
Joined: 1 Mar 2004
Posts: 4978

Maybe there is no calendar issue but a remaining lag is pushing the activities. Unfortunately the FF relationship you are using suggests me the lag is necessary and using date constraints to drive the start of the summer activities is not the solution.

Original Lag is what was typed in and is used when there is no progress on the activity. Remaining Lag is the lag that is leftover, after the activity has started.  Remaining lag is automatically reduced once the activity is started and the Data Date is moved forward with Statusing.

What is delaying your activities?

  1. I use different software so I just look at the links table to identify remaining lag on predecessors.     Image-095
  2. What is your Data Date?
  3. What lag (remaining lag) is shown for predecessor activity with FF lag?
  4. Is this link a driving link?
  5. Try looking at your trace logic chart for the delayed activities. It is dynamic, it moves as you move among activities, easier than using reports for this purpose.
  6. If your software does not helps or make it difficult to trace lags status consider modeling lag with an activity, a workaround of the late 1950’s, before I was born, when lag functionality was not available. It is a workaround still in use when Monte Carlo software cannot model probabilistic lag as if they forgot about lag. It is a workaround for long duration lags, especially when the software make it difficult to identify and adjust driving remaining lag.
  7. I do not expect P6 users to level their resources, some do not even resource load them. In any case if you are among the few P6 users that resource level their schedules remember to check for the possibility resource leveling delayed the activity.
Santosh Bhat
User offline. Last seen 15 hours 27 min ago. Offline
Joined: 15 Apr 2005
Posts: 311

Again, without being abel to see your schedule, Try Setting the F9 calculation to be 30-Nov at 17:00

Mia Ng
User offline. Last seen 1 week 6 days ago. Offline
Joined: 14 Jan 2008
Posts: 15

ah unfortunately I have signed the NDA, so cannot send the programme out as it contains sensitive info :"(, was just hoping to see if anyone had that issue before and if they could fix.

I think it has to have something to do with the F9. If I retype the duration of 65 days into the duration column, the end date goes back to 31 Aug. Or if I make a copy of the programme, then the copy programme show 65 days from 28 June to 31 Aug as well (i.e. correct dates). However, as soon as I F9, then the end date get pushed out to 1 June the next year.

Zoltan Palffy
User offline. Last seen 6 hours 1 min ago. Offline
Joined: 13 Jul 2009
Posts: 2842
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if you send me the project I wil figure it out 

Mia Ng
User offline. Last seen 1 week 6 days ago. Offline
Joined: 14 Jan 2008
Posts: 15

Many thanks Santosh. I have just checked all 4 recommendations of yours and everything seems to be in its place, so it is very strange that it happened (and only recently).

I've printed screen here in case you may see sth's wrong?

 

Predecessor and Successor

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capture_1.jpg

 

F9 window:

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capture2.jpg

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capture_3.jpg

 

Calendar setting:

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capture_4.jpg

Many thanks

Santosh Bhat
User offline. Last seen 15 hours 27 min ago. Offline
Joined: 15 Apr 2005
Posts: 311

Its hard to see if the predecessor is causing the issue as you've not shown it on the image. However somethings to check:

1) Double check the calendars, that a non-work day or even a non-work hour has been introduced in there over those periods

2) Is there a lag from the predecessor. By default P6 uses the precedessors activity calednar to schedule lags

3) Display the Duration unit to one decimal place to see if durations are actually more than a whole day and just being shown roudned down

4) Check the time that you're running your status update on If you're pressing F9 and calcualting from 00:00 rather than a work time period, this can also push activities out.