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).

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.

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

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 !

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

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