The duration of this fixed-duration task will change to accomodate



PMs are getting the below warning message on their Project Plans.

"The resource is assigned outside the original dates for task ..."
"The duration of this fixed-duration task will change to accomodate the
resource assignment"

What happens is that the Task duration (mainly end date) gets increased
(moves forward).

We found out that this is happening because one or more resource(s) on the
task has planned admin time (in timesheets) and that is causing the duration
of the task to shift. Task type is set to Fixed Duration and resource are
fully allocated (100%).

Issue: PMs are confused as to why "Fixed duration" task are undergoing
duration change? They want the Task duration to stay unchanged and work or
units to change, in such case.

How can we avoid Task duration to shift in the above scenario?



Gary Chefetz


One thing your users need to understand about tasks in all versions of
Project through 2007, is that they are calculated by the system. Among the
three variables: Work, Duration and Units, you can enter two, however
Project will always calculate at least one of these. So, the moment you have
data in a task that violates the algorithm's ability to maintain the fixed
duration of the task, it's going to change it. Project 2010 introduces new
task features that may solve some these issues people have. Understand that
Project is designed to show the reality that the data dictates, and not
necessarily what some of its constituents want to see.



Thanks for the reply. So, the Task type is set to Fixed Duration. Hence,
Project scheduling engine is trying to - Work = Fixed Duration * Units,

In this example, Resources are planning admin time, so it makes me believe
"Units" are being changed. The dillema I am facing is that why is Project
scheduling engine changing duration on a fixed duration task?!?! It should
change units or work. PMs have set task type to fixed duration for this very
reason as they do not want duration to shift. thoughts?

Do you think Resources being booked 100% on the task is the reason duration
is shifting ahead? If resources were not booked 100% on the task, will the
scheduling engine keep duration un-changed and bump resource unit % on the

Gary Chefetz


Just doesn't work that way. If you are going to change percent units or work
values on fixed duration tasks once they are defined, the durations will
change unless you make sure the entries don't force the scheduling engine
into it. A great way to keep fixed duration tasks fixed is not to put
resources on them!<g> You should make sure that effort driven scheduling is
turned off on all fixed duration tasks as well. Mostly, it's a matter of
training you users how to use the tool.
Jan 25, 2014
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The same error happened to me and I did as you said but my problem is that I update the project till the finish time , but some tasks never get 100 %!!!

can any body help me?


Nov 2, 2015
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I have a similar problem, but I am surprised to see that more people do not have the same.

I would like to specify duration and work to have project calculate assignment units.
If the equation holds true then I should be able to have projects lasting 1 day, with 2 hours of work needed, and resources capable of working 8 hours per day, return a 25% usage of that resource.

Instead, it seems that duration is changed even though I have specified fixed duration.

In short, how can one state that the units variable in the work=duration*units equation is the one you would like to have calculated?

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