Duration ??

[shawn]

TO all

I have a straight forward question (I hope)

I have an activity that is set to 400 Hrs of work. It shows the days for
work Duration correctly (with a ? showing estimated). I change to a 24 hr
calendar and the bar on the Gantt gets shorter and shows the correct
duration there but the Duration field still shows the original estimated
duration. How can I get the task to show the correct duration for the
activity? The start/end dates are correct just not the duration?

Is there a setting I am missing?


AHGA

Shawn

 

[Steve House]

Understand that duration is ALWAYS computed and stored as minutes. On the
Tools/Option menu, Calendar page you'll find settings "Hours per Day,"
"Hours per Week," and "Days per Month." These setting are the conversion
factors to convert duration minutes into more convenient units that you
might wish to use. The default setting is Hours per Day = 8. This means
that each increment of 480 minutes (8 hours) is considered "1 day" of
duration. If you work a 24 hours calenday that means that work procedes
24/7. If a task starts Monday at 8am and takes 24 hours, it will finish
Tuesday at 8am. Since this is 3 8-hour increments, that 24 hour period
encompasses "3 days" duration. The number of hours considered a "Standard
Day" is a global setting for all tasks in the project.

Are you sure you really want to use the 24 hour calendar? If you have a
task that requires 400 hours starting Monday 01 June at 8am, work will
procede continuously without interruption until midnight 18 June. Since a
proper task breakdown details tasks down to the level of 1 task being the
work done by one resource or a resource team, it means the poor guy you
assign to this task isn't going to have a lunch or dinner break, even get a
brief nap, see the wife and kids, or get any relief at all for 2 and a half
weeks. Are this really what you mean to do? It's not usually likely - what
people wanting to use the 24-hour calenday usually are trying to accomplish
is they have perhaps 3 8-hour shifts and as one shift goes home another
takes over task and continues the work. In that context, a task starting
Monday at 8am and finishing Tuesday at 8am really is "3 days" because it is
1 work-day for each of 3 shifts of workers, 3 work-days total. To get that
result, you do not use the 24 hour calenday, you use 3 different 8 hour
calendars; a day shoft, a swing shift, and a grave shift. Resource Joe's
calendar is the day shift, Resource Bill's is the swing, and Resource Bob's
is grave. Enter task task with 3 days duration starting Mon at 8am. It
will show ending Wed at 5pm. Now assign the three resources to it.
Duration is still 3 days (shifts) but it will start Mon at 8 and finish Tue
at 8, 24 hourts later.

Make sure you undersdtand clearly the difference between 400 hours of work
and 400 hours of duration. Even though both use the units "hours" they are
NOT equivalent - hours of work and hours of duration are competely different
measures. 1 resource working exclusive on a task for 1 hour does 1 hour of
work. 2 resources working together on that task for 1 hour do 2 hours of
work. 1 resource splitting his time 50/50 between the instant task and
something else does 1/2 hour of work in 1 hour of duration.

HTH

 

[shawn]

Steve

Thanks for the info.

Yes I know the 24 hour calander is not practical. WHat I am doing is just
making my own since my crews work roughly 20 hours per day so I have a
custom calendar created. We have 2 12-hour shifts and are more interested in
duration in days! Although most sites have 3 8-hour shifts our shifts are
not standard. We are calculating that we drive a tunnel at roughly 20
meters per day and thus calculating our advance per month based on that.

My question is more about the functionality rather then the process. I have
a task that is set to start on June 1st and goto July 1st. 30 days roughly.
Duration says 30d ? with standard calendar

I change the calendar to 24 hour and the start day says June 1st, Finish
date now says June 15th (roughly). Gantt chart shows correct time frame but
duration still says 30d? is there a way to show actual duration in days
instead of assuming that I want days/shifts

All I wanted to know was why the duration does not change from 30 days to
the correct 15 days. If I take the gantt bar and move it a miniscule amount
the duration shows correctly??

I'll read over your detailed expalination again and see if I can follow what
your refering too.

TFTH

Shawn

 

[Mike Glen]

Hi Shawn,

To add a comment, try going to Tools/Options.../Calendar tab and change the
hours per day to be 24 and hours per week to be 168.

Hope this helps - please let us know how you get on

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

 

[Steve House]

As Trevor and Mike said, but to reiterate. Project never computes durations
in clock-days (or weeks, or months) and there is no way to make it do so.
Durations are ALWAYS entered, stored, and calculated in minutes. You can
chose to enter and dispay duration with other more convenient units but all
the internal calculating is always done in minutes. What you are
describing, the number of 24-hour days that pass between when the task
starts and when it ends, is not duration, it is elapsed time. Elapsed time
is the time measured by your wrist-watch and Sparkomatic wall calendars, it
is real time. Duration is the number of potential working time minutes
between when the task begins and when it ends, "working time" defined by the
calendar governing the task. "Duration" does not include any time
designated as non-working in the calendar, "elapsed time" ignores the
distinction and includes both working and non-working time.

You said your crews work 20 hours per day. Then a moment later you said you
have 2 12-hour shifts. That doesn't compute. Are you saying a typical
workday for an individual worker is his 12 hour shift plus 8 additional
hours so that your individual workers each only get a total of 4 hours per
day of downtime????? Or are you saying that there are two crews, each of
whom work 12 hours per day with 4 hours overlap, so that the result is work
going on at the site 20 hours per day and down for the other 4?

Do not use the 24 hour calendar. Create 2 12-hour calendars. If work
procedes around the clock, perhaps one will be 6am to 6pm and the other 6pm
to 6am. If a task has one resource out of the day-shift crew on it, it will
start and stop as he comes to work and goes off and a task with 60 hours
duration starting Monday @ 6am will end Friday @ 6pm. If you add a guy from
the night shift to the task, the same 60 hour duration task that starts Mon
@ 6am will finish Wed at 6pm. The durations of both tasks will remain 60
hours (and thus the "days" will be the same because hours per day is a
global setting) because both of them consume 60 working-time hours from
start to finish. The elapsed time is what is different.

By the way, for simplicity I've ignored allowing for meal periods in the
calendar in the above discussion. In fact, a shift from 6am to 6pm with an
hour for lunch is an 11-hour duration calendar, not 12. Ignoring meal
periods introduces serious errors in real calendars.

A lot of this is made much simpler if you can just stop thinking about
durations in "days" at all. When you think durations, think hours. At
least that way you don't have to worry about a conversion - a project
standard "day" can mean 8, 10, 12, 7.456 or any other arbitrary number of
hours but "hour" always means 60 minutes.

 

[shawn]

Guys

Thank you very much to the assistance, I am sorry if I sound obtuse
I was confusing the duration's work days rather then actual "Real World "
days. What was throwing me off was the fact that it says 34d? To me that
is 34 days (calendar days).

Our shifts are 2 12-day shifts with about a total of 10 hours of actual work
time per shift. We really track calendar days not shift days so I was
looking for that info (we are quantity driven not resource driven)

What I'll do to show the calendar duration is just make a calculated
duration field and take finish date and subtract start date from it. It
should give me the correct duration is calendar days, that way I can have my
cake and eat it too. (I hope)

Again thanks for your patience!!

Shawn

 

[Steve House]

No problem to create a field for elapsed time just as you describe. But in
the process, don't lose track of the fact that the mere passage of time does
not drive projects towards their completion. It is only the passage of time
during which work is actually being done. That's why duration drops out
non-working time like days off, meal periods, statuatory holidays, etc.
Clocks run all the time but projects only progress when physical activity on
tasks is taking place.