Controlling the order of tasks

[Bobg]

Hello,

This may be a basic question to more experienced users, but until I get this
down I don't feel that I am using Project the most efficient way I can.

I am looking for the best way to let project work the way it is supposed to
and yet control the order of tasks when I want to. I have tried using
priorities combined with leveling and that seems to work some of the time,
but there are times when I am confused by what it does.

Here are two examples of the types of issues I am having:
1. Let's say I have 6 tasks that will be worked on by one resource (A1,A2,A3
and B1,B2,B3) where A1 is a predecessor to A2, A2 is a predecessor to A3,
etc. The same dependency holds true for the B tasks but there is no hard
dependency between the two sets of tasks. As a matter of preference, I would
like B1 to start when A3 is complete. I have tried setting higher priorities
to the A tasks but there are still times that project will schedule B tasks
to occur before the end of A3, even though they are a lower priority. I
suspect that priority is only related to leveling for over-allocations and
will not come into play for "regular" scheduling. Are my only options to
either create an artificial dependency or to edit the work schedule and force
things to the order that I would prefer?

2. Same scenario as 1 above but after leveling some tasks are placed WAY out
in the future for no apparent reason. Have checked constraint dates, actual
dates, etc. but cannot figure out why would happen. In the latest example,
the task in that was scheduled way out had a predecessor that finished 6
months before it and there was nothing scheduled for the resource for several
months before this task. Any ideas on things to look at in this case?

Thank you for your help,

Bob

 

[Jan De Messemaeker]

HI,

Whilst I don't have a clue about the task being pushed far out (resource
availability? Bug -->Service Pack install??) I wish to comment/help on the
first issue.

You say that there is no overallocation. Then why on earth would leveling
delay the B tasks? Why not start them rightaway parallel to the A tasks?
Indeed, leveling will only act upon overallocation of (a) resource(s)!

But supposing there is an overallocation on a resource, please be aware that
leveling acts on an amalgam of factors, and priority is one of them. I plays
a minor part in Standard Order, it plays a major (but not the only) part in
the Priority, Standard setting of leveling. In your example, my opinion is
that when priority numbers are seriously different, and Leveling order is
set to Priority, Standard, teh A tasks WILL be scheduled first.
Hope this helps,


--
Jan De Messemaeker
Microsoft Project Most Valuable Professional
+32 495 300 620
For availability check:
http://users.online.be/prom-ade/Calendar.pdf

 

[Dale Howard [MVP]]

Bobg --

If it were me, I would specify a Finish-to-Start (FS) dependency between the
A3 task and the B1 task. We call this type of dependency relationship a
Discretionary dependency, because it is a dependency based on the resource
assigned to the tasks rather than a mandatory relationship between the tasks
themselves.

Furthermore, I would also follow a Best Practice of adding a Note to both of
these tasks to indicate the Discretionary dependency relationship. If you
are using Microsoft Project 2007, you could also use Cell Background
Formatting and use a special color to indicate that this task pair has a
Discretionary dependency relationship as well. Just a thought. I hope the
others will share their opinions with you as well. Hope this helps.

 

[Bobg]

Thank you for your help Jan. In this example with the A and B tasks, it is
really just a matter of preference on my part that the B tasks finish prior
to the A tasks starting. These are two features in a version of software and
the developer prefers not to jump back and forth between the two. Since
leveling works only on overallocations I suppose there is no way to make
Project understand this preference for the original scheduling other than to
tell it that is the way it has to be with a dependency... does that sound
correct?

Bob

 

[Dale Howard [MVP]]

Bobg --

I should add that in my original answer, I am assuming that you have
assigned the resource to work full-time (100% Units) on every one of the six
tasks. Hope this clarification helps.

 

[Mike Glen]

I agree with Dale. I've always called it Management Logic to distinguish
its true nature from Physical Logic. Used sparingly, I see it as an
acceptable tool in our toolbags. The example I give is a situation where a
canteen kitchen with two gas ovens is being refitted with two electrical
ovens. There's no physical reason why one can't take out both ovens
together and then install the replacements. However, Management has said
that the kitchen must remain open, so remove one gas oven and replace it
with an electric one, then repeat for the remaining oven - Management Logic.

Hope this helps,

Mike Glen
Project MVP
See http://tinyurl.com/2xbhc for my free Project Tutorials

 

[Bobg]

Hi Dale,

Thank you for the information. Just to make sure I understand... there is
nothing special as far as Project is concerned about a 'discretionary'
dependency, right? It is just good to identify it as such so that it is known
that there is not a true dependency between the two tasks.

Thanks again,

Bob

 

[Dale Howard [MVP]]

Bob --

Yes, there is nothing special to Microsoft Project about a Discretionary
dependency. If you use them, the important thing is that YOU know they are
there, as indicated by things like task Notes and Cell Background
Formatting. Hope this helps.

 

[Steve House]

I think that would still fall into the category of a physical logic as it's
an operational requirement of the project's workflow. Both ovens can't be
out of service at once. The single task "Replace Ovens" becomes two
independent tasks, "Replace Oven A" and "Replace Oven B" linked FS.

 

[Mike Glen]

Hmmmm. I can see your point, Steve, and either will do. There is no
physical reason why the gas ovens can't be removed together. It is purely a
management decision. After all, the work could have been done at the
week-end without interrupting the canteen, but if it schedules to be done on
a weekday there would then be a gap until Saturday. The prime point is that
one can have logical relationships for other than pure physical reasons.

Mike Glen
Project MVP
See http://tinyurl.com/2xbhc for my free Project Tutorials