Project Duration vs Actual working project days

[Loutsa]

The project has duration of 110 days for example. The project commences in
July 06 and finishes in January 07. MS Project calculates a total of 350
days. How do I exclude the periods for which the project has idle time, and
for the duration to only show the actual working days of the project (total
of 120, and not 350 days)?

 

[John]

The project has duration of 110 days for example. The project commences in
July 06 and finishes in January 07. MS Project calculates a total of 350
days. How do I exclude the periods for which the project has idle time, and
for the duration to only show the actual working days of the project (total
of 120, and not 350 days)?

Loutsa,
Well you're throwing out several numbers that don't quite all jibe.
Project normally displays working time in its duration fields. This is
determined by the project calendar(Tools/Change Working TIme), and the
settings under Tools/Options/Calendar tab.

Now the question, what do you consider as "idle time"? Is it just the
days that no resources are actively working on any task or does it also
include those periods where a resource is charging the account but is
unable to do anything because he/she is waiting for someone else to
provide some parts/data? Looking at it another way, let's say a task has
an estimated duration of 5 [working] days. A resource is assigned at 50%
so the work content is 20 hours. Maybe he does all the work in the first
2 1/2 days or maybe he only works 4 hours per day for the full 5 days.
So what is the "idle" time? Is it 2 1/2 days, 0 days, or something else?

You could probably designate a spare field and call it actual working
days. You would need a VBA macro to populate it. Why VBA? Because you
would need an algorithm to take the definition of actual working days
and calculate it in coordination with calendar working time, resource
assignments and probably some other parameters I haven't thought of.

Why not just look at a more realistic parameter - Actual Work? You could
convert it to days if you want but then what is the conversion factor -
8 hrs, 6 hrs, or some variant thereof depending on the definition of,
"idle" time.

Some things that seem simple aren't necessarily that simple when viewed
in full context. I don't know if I've overcomplicated this or if I have
helped to shed some light. Hopefully the latter.

John
Project MVP

 

[Steve House]

I think you are mixing up duration and work.

Duration is the time between when a task or the project starts and when it
is done, minus any non-working time (ie a task starting the 1st of the month
and ending the first of the next month has a duration of ~20 days, not ~30
days because non-working time like weekends etc doesn't count). The
duration of a project is the time between when the earliest starting task
begins and when the latest ending task finishes and it is NOT additive - the
total duration is NOT the simple sum of the individual task durations. The
total duration of 3 110-day tasks running in parallel is 110 days. The
total duration of 3 110-day tasks running in sequence is 330 days. The
total duration of 3 110-day tasks running in sequence with a 15 day overlap
between each task is 300 days. The total duration of 3 110-day tasks
running in sequence with a 15 day lag time between each task is 360 days.

Work is the man-hours (or man-days if you prefer) that the resources put in
completing the task(s). Work IS additive. The total work on a task is the
sum of the works done by each of the resources assigned to it while the
total work on a project is the sum of the works of each of its individual
tasks.

Lets say you have a project consisting of just 3 tasks - A, B, and C - each
of which is 110 days in duration and all three can occur in parallel. If
you start in July and all three run together, you'll finish in January so
that must be similar to your situation. Now you put Joe on Task A, Bill on
Task B, and Sam on Task C. Each resource will put in 110 man-days on his
task. When you total the work, you'll find you have 110+110+110 man-days of
effort, again reasonably close to the 350 you are attributing as the
"duration."

HTH