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How can a Weather Calendar be Assigned to Multiple Tasks at Once? [ID 1277399.1]

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Dennis Hanks
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What I thought was going to be a trivial exercise is proving to be anything but.  What I wanted to do was model the impact of expected rain days.  Constructing the calendar was relatively easy using average rainfall and subtracting the number of Saturdays in the month in question then ranging the result.  Assigning the calendar was also relatively easy as long as I did it on a single activity.  The problem arises when trying to assign the calendar to multiple activities.  According to the Oracle Knowledgebase 1277399.1, a global assignment is not possible to a resource-loaded schedule.  

My question:  Does anyone have a work-around?  Pre-assigning the resource via P6 8.2 does not work, or at least not the way I did it.  Any thoughts appreciated.  Thanks

BTW: This is an intermediate step to avoid using a weather allowance activity.  Once I determine the impact of rain days, I was going to modify my Budegeted Units to achieve the P80 finish date in P6 and then apply various Risk Factors to the resulting xer file to get the 'final' result, then determine the relative impact of each factor via the Hulett Method.

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Santosh Bhat
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Rafael,

 

Yes Pertmaster > Primavera Risk Analysis (PRA) > Oracle Primavera Risk Analysis (OPRA)

Same product, different names, and no development in the past ten years - there are better tools available on the marketplace now.

 

Rafael Davila
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Santosh,

My warning is also about calendars applied to activities/resources to any software that have issues with multiple calendars.  

If we set aside the issue of software resource leveling and only use logic and multiple calendars Oracle P6 would still be unreliable as per the supplied references.  Because of the calendar issues in Oracle P6 I have seen many schedulers in Planning Planet as well as in LinkedIn warning about the use of multiple calendars, some go as far as suggesting the use of a single calendar. 

If OPRA stands for Oracle’s Primavera Risk Analysis then I would be worried about the calculations under multiple calendars even when not using the software resource leveling. 

A model that assigns weather calendar exceptions via a resource will be different to a model that assigns the exceptions to the activities.  If you assign the calendar exceptions to the resource these will not be inherited by any lag.  This might invalidate your risk model.  Use software that allows you to assign lag calendar independent of activities and apply calendar exceptions to lag when required. 

I agree with your suggestion about getting a better SRA tool than OPRA (if OPRA stands for Oracle’s Primavera Risk Analysis).

Santosh Bhat
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Rafael,

I'm not discussiing the mertis of using resources to model weather risk. I'm simply reply to Dennis' ogirinal question of how OPRA assigns weather calendars to activities in the schedule. Its done via the resources function. 

Manually impact a few activities using the weather modelling dialog. Then display the resources columns, note the aentries in the resources field for those activities that were manually impacted, then repeat for all other activities you want to impact.

Your point son the merits of modelling resources is for a seperate discussion.

Rafael Davila
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Weather resource is to me is an acceptable approach when the software resource leveling and calculations under multiple calendars are reliable.

  • I would not say Asta PP resource leveling is reliable.
    • Say one resource is a crane and another is a crane operator, you cannot schedule crane and crane operator at different times.  This is an issue Asta PP could not handle efficiently.  This is a very simple case, in more complex cases it could become harder or impossible to work around it. Please follow/click the link: Asta PP Resource Usage Plan
  • P6 is notorious for flaws in the calculations of dates and float values under multiple calendars.
    • PRIMAVERA P6 – FLOAT ON CRITICAL ACTIVITIES?
    • While it’s quite legitimate to use multiple calendars in any schedule, it can present problems if we attempt to mix those calendars within the logic of the schedule. That is to say activities on one calendar should not be linked to activities on a different calendar if at all possible. Doing so can generate some very perplexing results in not only the dates, but the critical path.
    • Oracle P6: Critical Path Identification Disorder
    • One of the most frequently used features of P6 is the capability of using different calendars to schedule different activities of the same project. However, the use of multiple calendars affects the Total Float calculations and accordingly the Critical Path identification.
    • I have talked to Oracle representatives in several occasions and created Enhancement Requests in Oracle, but unfortunately it seems that Oracle does not have any plans to enhance its P6’s scheduling algorithm in the near future. P6 users should not assume that P6 will always produce a reliable critical path even if the poor scheduling practices are avoided.
Santosh Bhat
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Rafael, you make some very valid points about planning and modelling risk in general. My response of using resources was a specific answer to Dennis' original question, about applying weather calendars to multiple activities in OPRA. The solution is via the resource assignments.
Rafael Davila
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The rain resource approach can be a double edged knife if your software is poor at modeling all resources must work together on the same team.  

  • Say one resource is a crane and another is a crane operator, you cannot schedule crane and crane operator at different times.  This is an issue Asta PP could not handle efficiently.  This is a very simple case, in more complex cases it could become harder or impossible to work around it. Please follow/click the link: Asta PP Resource Usage Plan
  • aace International - Planning for adverse weather
  • From the above AACEI reference you can see that their preferred method is to apply the weather calendar to the activities and no mention to weather resource is done.  Perhaps because AACEI recognizes resource leveling in P6 is poor, so poor that in their Recommended Practice for Delay Analysis the mentioning of the impact of resource constraints is avoided.  
  • Because actual adverse weather on any given period can be different to individual weather sensitive activities the use of weather calendars can be tricky.
  • At home the use of weather resource is not an option as the practice is to mandate assigning the weather days to an activity calendar.  UNIFIED FACILITIES GUIDE SPECIFICATIONS   3.3.9 Calendars - If an activity is weather sensitive it should be assigned to a calendar showing non-work days on a monthly basis, with the non-work days selected at random across the weeks of the calendar, using the anticipated adverse weather delay work days provided in the Special Contract [Clauses] [Requirements]. Assign non-work days over a seven-day week as weather records are compiled on seven-day weeks, which may cause some of the weather related non-work days to fall on weekends.
  • Using a resource calendar to take over an activity calendar can be confusing and error prone therefore I have a preference on using activity calendars for purpose of modeling rain days.  Still I do not believe it should be banished, let those responsible for the means and methods use the weather resource approach as well. 
  • There might be some scenarios where the weather resource is best/only option.  Such is the case when you have multiple teams working on different shifts on the same activity.  It might be that during the day the weather/temperature might allow for more available work days for day shift than night shift. In such case it is better to use different weather resource for night shift as long as the calendars are compatible. - NEVER SAY NEVER.
  • Because Weather Days are Calendar Exceptions users of Spider Project transfer the selected Calendar Exceptions on the calendars exception table to any calendar by double clicking while holding the selected exceptions and then selecting the calendars from the dialog box. - EASY
Santosh Bhat
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Do it using Resources. Or better yet, get a better SRA tool than OPRA.

Robert Dawkins
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Duplicate post
Robert Dawkins
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So, You change the assigned “weather” calendar to reflect actual weather during that reporting period. I know this is probably obvious to the more experienced. I’m sure I’m probably over thinking something that’s simple. Thanks
Zoltan Palffy
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why doen you just create a weather sensitive calendar then filter for the activites that are weather sensitive. Add a column for calendars assign the 1t activity in the calendar column to the weather sensitive calendar and then do a fill down. DONE !

Rafael Davila
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https://thecmsolution.com/site/wp-content/uploads/Delbert_2014-01-22.pdf


Methodology forAccounting for Actual AdverseWeather:


In the use of weather calendars, this methodology includes changing the weather calendar from the planned adverse weather to the actual adverse weather. The results of this maintenance are that the Actual Durations for all activities that were affected by adverse weather are accurate.

Robert Dawkins
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Weather Calendar Question: How are weather calendars handled during updates. What is the procedure when updating an activity that has a weather calendar assigned to it with non-work days on days that have actual work. in other words no rain occurred during between the time of the last update. I'm sure this is probably very simple but weather calendars are new to me being that there are other ways to handle rain days.

Thanks

Rafael Davila
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Vladimir,

As far as I know P6 is not capable of true CPM SRA if this means Schedule Risk Analysis. Primavera exports the schedules using what they call xer files to different software.

It is a different software who is CPM SRA capable !

The software was initially called Pertmaster and now it is labeled Primavera Risk. This software uses different algorithms than P6 and can yield different resource leveling distributions and I suppose can yield different values of float. It might happen that each of the hundreds or thousands iterations using Primavera Risk can yield hundreds or thousands different results if computed using P6 engine because of the differences on their algorithms. It is not only about different float values and project duration it is also about the handling of constraints, especially when working multiple constraints on the same activity where P3, SureTrak and perhaps P6 have some problems.

It is managing with different software if you use both, something that does not make much sense to me.

Well maybe both yields equally wrong values of float. Guess this means equally wrong float probabilities distributions.

On the other hand Spider in all its versions with the exception of Lite version provides for risk analysis within the software, it uses the same engine and always yields correct values of Resource Critical Path calculations and resource constrained floats.

About Asta I believe SRA is a separate module and I suppose it uses the same engine as Asta because both modules were developed by the same company, by the same team. This although different to Spider approach to include SRA within the software is a good option.

Best regards,

Rafael

Dennis,

you wrote: As far as I know none of the programs you mentioned are capable of SRA.

What is SRA?

Did you try Asta and Spider?

Best Regards,

Vladimir

Rafael Davila
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My porposal is not about PRA it is about P6 basic calendars, about your statement "Assigning the calendar was also relatively easy as long as I did it on a single activity. The problem arises when trying to assign the calendar to multiple activities". 

Is about a way to just do this, to assign a single calendar [whichever you want] to multiple activities at once without using global assigments. 

Whatever you say about your probabilistic methods is a separate issue I am not addressing.

Dennis Hanks
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Rafael;

While I appreciate your support, I am not sure I understand your comment.  There are probabilistic calendars available in PRA, but I do not think they are relevant to the current discussion.

Rafael Davila
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Maybe you can use a UDF to identify and filter the activities you want to change calendar and then after filtering you can execute the change as suggested in the following link.

http://www.haironfirepm.com/2012/07/28/primavera-p6-use-fill-down-to-change-activity-calendars/

After you assigned the calendar you can then change you weather calendar workdays to do your what-if.

Dennis Hanks
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Mike;

The bridge is straightforward and would be a P6 calendar.  For inclement weather, the simple method to model variability (risk) is to add a 'weather allowance' that sums all the 'average days' for the period and then puts a range to that sum to get an expected finish date - not possible to range calendars, as far as I know.  What I am trying to do is to more exactly model the variability of rain days, which is proving more problematic than I expected - but in for a penny, in for a pound.  I have the model working, but am not getting the expected result.

To account for rain on the weekends (~30% of the time, with an indeterminate number being 'make-up Saturdays', I would downward adjust the determined range.  Say the average was 10 days per month and the range was determined to be 8-14.  I would probably adjust the range to 7-13, I need to 'play' with this before I set the rule.

As far as I know none of the programs you mentioned are capable of SRA.

Mike Testro
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Hi Dennis

I have used weather patterns for offshore oil rigs in a monsoon zone when all work is embargoed.

The simplest way is to set non working days on the monsoon calendar.

The same techniquue applies to all non-working embargoes - I am currently working on a project involving a bridge over a river where no work is allowed during the fish breeding season - 31st March to 31st August - put it on the calendar.

I also use predictive inclement weather from previous local weather records where I take the average days per month and then set them at random on the calendar - it rains on weekends too.

I think you may be trying to overcomplicate what is really a very simple process - but it helps that I use Asta PowerProject which - Like Spider - is so user freindly.

Best regards

Mike Testro

Dennis Hanks
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Mike;

Actually I am trying to take it off the calendar so it can be 'risked', but I did not think the "weather allowance" activity was the best method - certainly easier than what I am attempting to do.  So far it is requiring two reflections and three global changes, the last may involve several iterations.  So far I am not getting the results I am expecting.

I use average rainfall for whatever city is nearest the jobsite, then adjust for number of Saturdays (assumes 5X10 with Saturdays as a make-up day - Gulf Coast standard) then build the Weather Module Event calendar accordingly [contract stipulations would replace this determination].  Requires stripping all existing resources and applying the weather resource, then running the risk analysis.  After determining the P80 finish date, I  then adjust a 'clean' reflection to achieve the expected finish date (factoring the budget labor hours), then running the normal estimate uncertainty and any relevant risk factors to get the P80 contingency values.  May be more trouble than it is worth.  OPRA should do all of this more or less automatically, but right now you cannot run the weather module and risk factors simultaneously.  Oh well.

BTW: I am a fan of P6.  Most of our construction work (Oil & Gas) is exposed, so most of the ativities have to have the weather event calendar (OPRA) assigned and this is the only way I have found to do it 'globally' in a resource loaded schedule (is there any other kind?).  If anyone has a better idea, please raise your hand.

Mike Testro
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Hi Dennis

You are doing the right thing by putting potential weather delay on the calendar.

If you have inside work then you will need at least two calendars.

Is there not a calendar column in P6 where you can copy or import the calendar code?

I avoid P6 wherever possible but surely you can add multiple calendars without going to every task?

Best regards

Mike T.

(btw My P6 password is P6iscrap -  the support staff just hate typing it in)