Multiple resourced tasks run shorter with fewer resources

[Jo_Martin]

I am using multiple resources as a pool carry out several tasks - with the
intention that whoever is available can be allocated. I've run into problems
as it seems that P2007 needs to use all the resources allocated before it can
schedule the end of a task. If I set up a task as effort driven and allocate,
say 7 resources, Project will allocate resources as they are available - and
if not available, will leave the resource on the task at 0 hours.
It seems that Project is waiting for this resource to be available (for 0
hours) before it can schedule the end of the task.
To illustrate this behaviour, set up a multi task project (I used 12) and
allocate the same resources to all ( say 7), same work for each task (say 56
hours). Note the finish date. Now allocate non working time to one resource
(say a week). The tasks will increase in duration, and the finish date will
move out because of the holiday - fair enough.
Now delete the resource with the holiday. The overall project finish date
gets earlier....

So with less resource availablity, the project duration is shorter!

While that is an interesting exercise, I'd really like an answer to my
problem, which is how to get maximum resource on a task from a pool of
resources, none of whom are critical to completion of the task.

Cheers
Jo

 

[Jan De Messemaeker]

Hi,

Doing what you do you do not decrease the availability but the NEED for the
unavailable resoruce so it is absolutely logical the task now ends earlier.
As you have noticed, Project expects all resources assigned to a task to do
their work, and the different assignments react independently of one another
i.e. ther is no compensation: once the resources are asigned to the task,
when one resource picks up more work, that just increases the total work on
the task, it does not decrease the work of the others.
It's not whoever to do the work: each resoruce assigned has to d their work
or you have to delete the assignment - which decreases the total work and
hence may mke the task end sooner.

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

 

[Jo_Martin]

Thanks for the reply, Jan.

Re your last point - the tasks are all set as fixed work, so if I delete a
resource it spreads out the work amongst the rest - the amount of work is the
same but with less resource it get's done faster.

This is at the root of the problem I have - trying to schedule tasks with
multiple resources who all have their own calendars. I'm looking for a way
to allow Project to schedule in the best way possible. I could do it with a
generic team ID (not individuals) set at 700% availability, but this can't
reflect different leave profiles or the fact that some resources need to
belong to more than one team. Is there a way to use groups to solve this?