Adding resources to fixed duration tasks

December 16, 2017 - 05:57 am
1 comment(s)


I am struggling a bit with adding resources to a fixed duration task. Any help is appreciated.


If you have a fixed duration task, ProjectLibre does not appear to properly handle resource adjustment by work, only by units. 

...Unless I am missing something! Is this a bug?


My goal is to add resources at less than 100% (units) to a fixed duration task. This is a pretty common situation in my projects. I am assuming here that:

Work = Duration X Units

And that the behaviour should work something like the attached image (courtesy of http://epmstrategy.com/WhitePapers/EPM%20Strategy%20Task%20Types.pdf

So a hypothetical case: 5 day fixed dur, Resource A @ 50% units (i.e. 20 hrs work)

  • Step 1: add task of 5 day duration
  • Step 2: make task fixed duration and turn off effort driven
  • Step 3: assign Resource A (defaults to 100% units, 40 hrs work)
  • Step 4: adjust Resource A by:
    • Option 1: Change units to 50% --> This works as expected = total duration 5 days, work is 20 hrs
    • Option 2: Change work to 20 hours --> This does not work = 40 hours work (what!?) 200% units, total duration 2.5 days); the maths works, but the task duration was most definitely not fixed.
  • Step 5: Adding a second resource at lower work follows the same pattern above, except that in Option 2 (adjusting work), the units are correctly adjusted and the task duration is fixed. Presumably, this is because the task is driven by Resource A.

Interestingly, If I pause at Step 4 Option 2, and try to fix it back by over-writing the work again to 20 hours: work changes back to 40 hours, units are 400% and duration is 1.25 days. This keeps going, theoretically infinitely.

While the above suggests I can work around the issue by only adjusting units, this is a bit of a pain as I will need to figure out, each time, what % equates to a specific amount of work. This is even more of a pain with irrational numbers or repeating fractions. It could lead to small errors in estimates (potentially significant in the aggregate).


1 Comment

January 11, 2018 - 06:23 am

I have found projectlibre to be very buggy when it comes to "Duration" and "work". I am still looking for a fix. For example when you set the work hours to 20hr, and add resources to it (Duration will change), then remove the resources the work hours will change, even if you change Type to fixed work. CRAZY.