Which resource calendar drives the task? RRS feed

  • Question

  • Hi all

    I have multiple resources that work different hours and have set up calendars for each of these scenarios (i.e. 10 hour work days vs. 8 work hour days).

    On some tasks, I have resources with an 8 hour day and some with a 10 hour day (both assigned to the task 100%) and I have noticed my critical path gets a bit wonky.

    I'm wondering if which calendar really drives the task (and subsequently the CP)? 

    I was considering reducing the resource with the 10 hour calendar to 75% but wanted to be clear on how Project has been calculating.

    Thanks in advanced!

    Using MSP 2010 PRO with SP1


    Wednesday, April 10, 2013 3:59 PM

All replies

  • Hi Shelleyb,

    The duration of the task is driven by which finishes last on the task. That is a factor of assignment units, work, and calendars.  I suggest splitting your screen to show the task form and applying the Schedule format to the Task Form.  Changing assignment units for the resources who finish earliest may very well make them finish last.

    I hope this helps.


    Wednesday, April 10, 2013 4:06 PM
  • Hi Julie  thanks for your response.

    So, I understand that if the task is schedules for Monday and the duration is 4 hours and my 8 hour/day resource does not have time to complete it on Monday, but my 10 hour resource does Project pushes the task til Tuesday or over allocates the 8 hour resource.

    What I still don't know is does Project look at resources in the order I list them?

    When does it over allocate as opposed to rescheduling?


    Wednesday, April 10, 2013 4:47 PM
  • Hi Shelleyb,

    There is something more going on here than you're letting on :-)

    If the resource is assigned to the task scheduled for Monday and and the resource is already assigned to another task scheduled for Monday - you're correct - the resource will be overallocated. However, unless you have your leveling calculations set to Automatic - the task should still be scheduled for Monday -- no pushing til Tuesday."

    However - if you assign aresource who is not assigned to other tasks - no overallocation.  Project will not select which resource is the best or most available - it will simply calculate the work.  If the resource has non-working time in his/her calendar - the task will be rescheduled.

    I hope this helps and let us know more about what you were hoping to accomplish.


    Wednesday, April 10, 2013 11:18 PM
  • Shelley, you were asking about which calendars drive task scheduling. The choices are generally Project, Resource or Task calendars.

    Every project will have a calendar - usually a standard that is derived from the Global template. You may well have updated this with company holidays and set it for the standard work hours. Left to itself project will schedule tasks according to this calendar. If that's a 1 day, 8 hour per day task and you've assigned your two resources (8 hour day and 10 hour day) both at 100%, I would expect to see them both scheduled for 8 hours and the task to finish at the end of day 1. Looking at Resource B's utilization, you would see that they have 2 hours of remaining availability.

    Every resource will have a calendar. They start off being the same as the standard calendar that is used for the project. If a resource takes vacation and those days are marked as non-working in his/her calendar, then they will not be scheduled to work on that day. In your example, if Resource A has the day of the 1 day task marked as vacation, their work for that day will be pushed off to the next day Resource A is available. Project will do nothing about checking whether B has any remaining availability to fill in for A.

    Some tasks may have a task calendar. This overrides the Project calendar for this particular task. Let's say you used the task calendar to describe your 1 day task as fitting into a 10 hour day. Depending on how you specify your assignments, you might well end up with Resource A doing 8 hours work on day 1 and 2 hours on day 2. Resource B would do all 10 hours on day 1.

    Hope this isn't too confusing...


    Thursday, April 11, 2013 12:38 PM
  • Thanks for your response Julie, but that wasn't what I was trying to get across.

    Resource A - 8 hour work day

    Resource B - 10 hour work day

    Resource A and B both assigned to a task for Monday.

    Whose calendar "wins"?


    Wednesday, April 17, 2013 4:05 PM
  • Thanks for your response Graham.

    I fully understand the difference between Project, Task and Resource calendars.

    What I'm not clear on is which resource calendar takes precedence when there are two resources on a task that have calendars that conflict.

    Does project look at the first resource identified?


    Wednesday, April 17, 2013 4:10 PM
  • Shellyb,

    Both resources' calendars "win."  The two resources' assignment together add up to the task.  Assuming you are not applying a task calendar, Resource A works according to his calendar and the number of hours you assigned to him, while Resource B works according to her calendar and the number of hours you assigned to her.  You can see this in the Resource Usage view.

    You also might find the Task Inspector useful in evaluating what is driving the task overall.

    Reid McTaggart – DeltaBahn Vice President
    Blog | Twitter | LinkedIn Please click Mark As Answer; if a post solves your problem or Vote As Helpful if a post has been useful to you. This can help other community members reading the thread.

    Wednesday, April 17, 2013 4:33 PM
  • Thanks Reid, but to me it's still not clear on how Project will look at these two resources. I must not be asking the question clearly enough.

    When a resource is assigned to a task but already has work assigned to them on the same day this new task is scheduled to start, Project will decide to either over allocate the resource or move the task. How is this decided?

    When there is more than one resource assigned to a task and one of the resources already has work assigned to them on the same day the new task is schedule to start but the second resource has enough availability to complete the task on the scheduled day, what does Project do? (Example below)

    Resource            Availability/Day    Current Workload      New task adds               Over allocation

        A                          8hr                     5hr                           4hr                              1hr

        B                        10hr                      5hr                          4hr                             1hr 


    Wednesday, April 17, 2013 5:48 PM
  • Project will over-allocate the resource, unless and until you apply resource leveling.  If you apply resource leveling, then whether or not the work on that particular task assignment gets rescheduled will depend on the leveling options you have set and the particulars of the task, such as its ID number or its Priority.  If you also have open other project(s) in which the resource has a conflicting assignment, then leveling will also take into account the Project Priority, which is set in the Project Information dialog box.

    I hope this helps.

    Reid McTaggart – DeltaBahn Vice President
    Blog | Twitter | LinkedIn Please click Mark As Answer; if a post solves your problem or Vote As Helpful if a post has been useful to you. This can help other community members reading the thread.

    Wednesday, April 17, 2013 6:10 PM
  • Hi Shelley,

    On top of Reid's perfect explanations, Shelley, when thinkin about this please forget about "task" altogether. Project works on the assignments as if they were individual tasks, andthe TASK is mrely a combination of the assignments (its start being the arliest of all assignments, its finish the latest)


    Wednesday, April 17, 2013 7:03 PM