Is there a resource leveling bug/error in Project 2013 and 2016? RRS feed

  • Question

  • Dear all,

    Try this: add three tasks with durations of 6d, 2d and 3d. All are "fixed duration" and "As soon as possible". Assign John 100% on task 1 and 2 and Mary 100% on task 2 and 3. If you level all three tasks then the result is correct in Project 2010 but it's wrong in Project 2013 and 2016.

    Leveling options are: "Day by Day", check "Clear leveling values ...", "Level entire project", leveling order "Standard" and the rest is unchecked.

    Why is Project 2010 right? With the standard leveling order and all tasks at the same start date, the task with the most slack will move first. This according to the rules described in the help. The second task should move to the end of the project because for both resources John and Mary this task has the most slack compared with the other tasks.

    Why are Project 2013 and 2016 wrong? When leveling this example project in Project 2013 and 2016 the second task does not move and the other tasks are put behind it. Thus ignoring the basic rules of standard leveling. This does not cause the end date of the project to be different but the schedule of the individual tasks is!

    Is there any reason why Microsoft has changed the leveling order or is it simply another bug/error?

    Thanks in advance,


    Tuesday, September 27, 2016 9:09 PM

All replies

  • Hi Theo,

    I just tested it with Project 2016 and it worked as expected: the task 2 moved at the end of task 1.

    Here are my leveling options:

    Hope this helps,

    Guillaume Rouyre, MBA, MVP, P-Seller

    Wednesday, September 28, 2016 7:12 AM
  • Hello Guillaume,

    Remove all checkmarks at "Leveling order". Then the error occurs in Project 2013/2016.

    The cause of the difference between 2010 and 2013/2016 is the option "Leveling can adjust individual assignments on a task". When th option is switched on the whole task can move and within the task individual assignments also can move independently. Switched off the whole task still can move without moving individual assignments within the task. Not so in 2013/2016 . It seems leveling the whole task is then skipped. This is what I think is the error.

    Any thoughts?


    Wednesday, September 28, 2016 8:02 AM
  • Indeed if you uncheck "Leveling can adjust individual assignments on a task", task 2 cannot be leveled since it require to adjust 2 assignments. I don"t have 2010 and 2013 so I cannot test it on those previous versions.

    Hope this helps,

    Guillaume Rouyre, MBA, MVP, P-Seller

    Wednesday, September 28, 2016 9:34 AM
  • Hello Guillaume,

    I've attached screenshots of the latest three versions of Microsoft Project. As I've mentioned before: when you remove the checkmark in front of "Leveling can adjust individual assignments on a task" this should influence the relative location of the assignment WITHIN that task. In Project 2013 and 2016 it seems that it simply stops leveling the task as a whole when there are more then two assigments. And I guess that this is incorrect.



    Project 2010

    Project 2013

    Project 2016

    Wednesday, September 28, 2016 11:24 AM
  • Hi Theo,

    Documentation of "basic rules of standard leveling" are pretty sparse.  I've concluded that those rules are essentially whatever Microsoft decides they should be to satisfy the bulk of the user base.

    Leveling in Project 2010 definitely has the potential to change the indicated CPM critical path.  Based on one example which I wrote about in my blog, leveling rules in 2013/2016 may have been tweaked to limit the critical path impacts. Clearly this doesn't show in your example, however, so I can't comment further on it.  The leveling rules are essentially a black box. 

    Wednesday, September 28, 2016 3:09 PM
  • Hallo Tom,

    Your definition of the leveling rules being a "black box" has oddly enough put me on the right track. I started playing around with multiple assignments to single tasks. In Project 2010 the order of leveling tasks with over-allocated resources was: Later start date first > if start dates are equal then tasks with more slack first > if both are equal then less priority first > if all is equal then higher ID number first.

    In short: start date > slack > priority > ID. This is described in brief in the Help file of all Project versions.

    In Project 2013/2016 they seem to have added another criterium: tasks with multiple resources first > then the previously mentioned order. Why has this been done? I cannot find any reason for this decision. Or is it a mistake? In the Help file this extra feature has not been added. And I wonder how many of these leveling criteria have been left out and put in the "black box"?

    See the images showing Project 2010 and 2016 with their different leveling results with multiple assignments.

    Hope this has helped,


    Project 2010

    Project 2016

    Project 2016

    Wednesday, September 28, 2016 8:30 PM
  • Theo,

    You are right that the same settings, all options off, produces different results in different versions as you describe. I checked it.

    I hope that you analyse it to death and come up with whatever the rules are inside the black box.
    MS thinks that if they don't tell us the rules we won't know what they are, but I think you are just the guy to figure it out.

    Meanwhile, I will just level as I have always done. When I hit the button and get a solution, I am re-assured that there is at least one solution, and probably more than one, and perhaps a better one (although that requires a definition of "better"). Then I bend it to my will by assigning priorities and level by priority. A solution is a solution and produces a plan which is at least feasible from one that isn't. But it cannot be expected to be optimal. I can live with that.

    Thursday, September 29, 2016 9:46 AM