Duration Not Right When For a 24-hour Resource

[Mike]

I have a Fixed Work task that will take 100 hours of Work. The resource is a
piece of equipment that is allocated at 100% Units on the 24 Hours Base
Calendar.

The Duration, however, is calculated at 12.5 days in the Task view, which is
what you'd expect for the Standard Base Calendar (8 hours/day). The Duration
should be just over 4 days for this resource at 24 hours/day, which is how it
appears in the Gantt chart (blue bar extends over a four day period).

What could be causing this? Thanks.

 

[Jan De Messemaeker]

Hi,

Days as a unit of time are not calculated through a calendar, nor are they
the difference between start and finish in true "days".
Days are the number of duration hours divided by what you find in Tools,
Option, Calendar, Hours per day. Full Stop. No link to any working time
calendar whatsoever.

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

 

[Mike Glen]

Hi Mike,

Welcome to this Microsoft Project newsgroup

If all your work is on a 24 hour basis then you should change the working
hours: see FAQ Item: 5. Default Working Hours. However, I suspect this is a
one-off and Project cannot handle effectively different calendars - it has
to pick one to show - the standard project calendar based on an 8-hour day
as you discovered. Don't forget that although the Duration shows 12.5 days,
the Work is correct at 100 hours. You'll have to live with that.

FAQs, companion products and other useful Project information can be seen at
this web address: http://project.mvps.org/faqs.htm
Hope this helps - please let us know how you get on

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

 

[Mike]

Thanks for your reply, Jan.

I'm baffled by the purpose of having the 24-hour calendar if it's not used.
Why have it?

--

-Mike

Hi,

Days as a unit of time are not calculated through a calendar, nor are they
the difference between start and finish in true "days".
Days are the number of duration hours divided by what you find in Tools,
Option, Calendar, Hours per day. Full Stop. No link to any working time
calendar whatsoever.

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

 

[Mike]

Thanks for replying, Glen.

We have a mix of resources where some of our equipment is run over a 24 hour
period, but the people and other equipment will be utilized within the
standard 8 hours workday.

If project can't handle the use of multiple calendars, then why does it know
that the duration is 4 days when displaying the Gantt chart bars? Project's
inability to handle multiple calendars comes as a shock and disappointment in
what I would consider a pretty common scenario.

Approaching the problem another way, if the calendar options were set so
that "Hours per day" were 24 hours rather than the default 8 hours, would
Project schedule tasks properly since working time of the 8-hour-per-day
resources were restricted by their Standard calendars?

--

-Mike

Hi Mike,

Welcome to this Microsoft Project newsgroup

If all your work is on a 24 hour basis then you should change the working
hours: see FAQ Item: 5. Default Working Hours. However, I suspect this is a
one-off and Project cannot handle effectively different calendars - it has
to pick one to show - the standard project calendar based on an 8-hour day
as you discovered. Don't forget that although the Duration shows 12.5 days,
the Work is correct at 100 hours. You'll have to live with that.

FAQs, companion products and other useful Project information can be seen at
this web address: http://project.mvps.org/faqs.htm
Hope this helps - please let us know how you get on

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

 

[Steve House]

It's not that Project can't use multiple calendars - it does so very nicely.
The confusion arises when one forgets that duration is ALWAYS actually
measured and calculated in units of working time minutes to the nearest
10th. In order to use more convenient units of days, weeks, months, etc,
they have to be converted to and from minutes. The conversion factors
applied are global within a project and independent of the working time
calendar. With the default hours per day setting of 8
(Tools/Options/Calendar) ANY time period of 480 minutes is considered a
"day." The calendars, OTOH, determine WHICH minutes out of the 24-hour
sunrise to sunrise day are to be considered working time. We enter a task
with a duration of 3 days, ie, 1440 working time minutes, starting Monday @
8am. If the calendar governing that task is the standard 8-hour default
calendar, those 3 480-minute "days" run 0800-1700 Mon, 0800-1700 Tue, and
0800-1700 Wed. On the other hand, if the 24-hour calendar is governing that
task, those same 3 480-minute "days" run 0800-1600 Mon, 1600 Mon-0000 Tue,
0000-0800 Tue. If the task is assigned to a resource who works part-time,
having a calendar that shows his hours of work as 8am to 12 noon Mon thru
Fri, the same 3-day (1440 working time minute) task will start Mon 0800 and
end the following Monday at 12 noon, 7.5 actual elapsed ordinary
wall-calendar days later, each elapsed calendar day Mon through Fri only
'burning up' 240 working time minutes, thus requiring 2 sunrise-sunset days
to equal 1 working "day."

HTH
--
Steve House [Project MVP]
MS Project Trainer & Consultant
Visit http://project.mvps.org/faqs.htm for the FAQs

Thanks for replying, Glen.

We have a mix of resources where some of our equipment is run over a 24
hour
period, but the people and other equipment will be utilized within the
standard 8 hours workday.

If project can't handle the use of multiple calendars, then why does it
know
that the duration is 4 days when displaying the Gantt chart bars?
Project's
inability to handle multiple calendars comes as a shock and disappointment
in
what I would consider a pretty common scenario.

Approaching the problem another way, if the calendar options were set so
that "Hours per day" were 24 hours rather than the default 8 hours, would
Project schedule tasks properly since working time of the 8-hour-per-day
resources were restricted by their Standard calendars?

 

[Mike]

Thanks for replying, Steve.

I believe what you're saying should produce the duration I'm expecting, i.e.
100h, or 6000 minutes, of Work broken up into (3) 8-hour (480-minute)
segments per day (as you've described) would result in a duration of just
over 4 days. Why am I seeing 12.5 days?

I must not be seeing the whole picture...

--

-Mike

It's not that Project can't use multiple calendars - it does so very nicely.
The confusion arises when one forgets that duration is ALWAYS actually
measured and calculated in units of working time minutes to the nearest
10th. In order to use more convenient units of days, weeks, months, etc,
they have to be converted to and from minutes. The conversion factors
applied are global within a project and independent of the working time
calendar. With the default hours per day setting of 8
(Tools/Options/Calendar) ANY time period of 480 minutes is considered a
"day." The calendars, OTOH, determine WHICH minutes out of the 24-hour
sunrise to sunrise day are to be considered working time. We enter a task
with a duration of 3 days, ie, 1440 working time minutes, starting Monday @
8am. If the calendar governing that task is the standard 8-hour default
calendar, those 3 480-minute "days" run 0800-1700 Mon, 0800-1700 Tue, and
0800-1700 Wed. On the other hand, if the 24-hour calendar is governing that
task, those same 3 480-minute "days" run 0800-1600 Mon, 1600 Mon-0000 Tue,
0000-0800 Tue. If the task is assigned to a resource who works part-time,
having a calendar that shows his hours of work as 8am to 12 noon Mon thru
Fri, the same 3-day (1440 working time minute) task will start Mon 0800 and
end the following Monday at 12 noon, 7.5 actual elapsed ordinary
wall-calendar days later, each elapsed calendar day Mon through Fri only
'burning up' 240 working time minutes, thus requiring 2 sunrise-sunset days
to equal 1 working "day."

HTH
--
Steve House [Project MVP]
MS Project Trainer & Consultant
Visit http://project.mvps.org/faqs.htm for the FAQs

 

[Mike Glen]

Hi Mike,

Project does calculate and schedule taking into account all the calendars in
use, witness the correct Gantt Chart representation. What it does is to
represent the Duration in the table based on the number of hours in a day in
the project Standard calendar, declared in Project/Project Information. It
has to pick one calendar and that's the one Microsoft has chosen to use:
100hours at 8 hours/day = 12.5 days.

Mike Glen
Project MVP

 

[Steve House]

If a "day" is defined as any 8-hour segment, a task that starts Monday at
8am and run continuously until Tuesday 8am will show "3 days" as the
duration in the Gantt chart task table even though in our normal world we
would say it's only 1 day. 24 hours / 8 hours per duration-day = 3
duration-days. Duration time is only loosely related to time as indicated
on the clock on the wall or tracked by conventional calendars such as your
day-planner. Think Star-Trek - the Enterprise used an Earth-standard day to
record time that bore no relation at all to the rotational period of the
planet they were visiting. In Project a 'standard-day' is defined as every
X working minutes, X being defined by the setting in Tools/Options/Calendar.
In your example, because work is proceeding 24/7, the number of working time
minutes between Monday 8am and Friday 12 noon IS the same as the number of
working time minutes in 12.5 standard 8-hour workdays, thus in duration days
the duration of that task is 12.5 days, not 4.25 even though the bar on the
graphic only covers four days + out of the week. There are 12.5 8-hour
segments between start and end, thus it is 12.5 days duration.
--
Steve House [Project MVP]
MS Project Trainer & Consultant
Visit http://project.mvps.org/faqs.htm for the FAQs

Thanks for replying, Steve.

I believe what you're saying should produce the duration I'm expecting,
i.e.
100h, or 6000 minutes, of Work broken up into (3) 8-hour (480-minute)
segments per day (as you've described) would result in a duration of just
over 4 days. Why am I seeing 12.5 days?

I must not be seeing the whole picture...

--

-Mike

It's not that Project can't use multiple calendars - it does so very
nicely.
The confusion arises when one forgets that duration is ALWAYS actually
measured and calculated in units of working time minutes to the nearest
10th. In order to use more convenient units of days, weeks, months, etc,
they have to be converted to and from minutes. The conversion factors
applied are global within a project and independent of the working time
calendar. With the default hours per day setting of 8
(Tools/Options/Calendar) ANY time period of 480 minutes is considered a
"day." The calendars, OTOH, determine WHICH minutes out of the 24-hour
sunrise to sunrise day are to be considered working time. We enter a
task
with a duration of 3 days, ie, 1440 working time minutes, starting Monday
@
8am. If the calendar governing that task is the standard 8-hour default
calendar, those 3 480-minute "days" run 0800-1700 Mon, 0800-1700 Tue, and
0800-1700 Wed. On the other hand, if the 24-hour calendar is governing
that
task, those same 3 480-minute "days" run 0800-1600 Mon, 1600 Mon-0000
Tue,
0000-0800 Tue. If the task is assigned to a resource who works
part-time,
having a calendar that shows his hours of work as 8am to 12 noon Mon thru
Fri, the same 3-day (1440 working time minute) task will start Mon 0800
and
end the following Monday at 12 noon, 7.5 actual elapsed ordinary
wall-calendar days later, each elapsed calendar day Mon through Fri only
'burning up' 240 working time minutes, thus requiring 2 sunrise-sunset
days
to equal 1 working "day."

HTH
--
Steve House [Project MVP]
MS Project Trainer & Consultant
Visit http://project.mvps.org/faqs.htm for the FAQs

Thanks for replying, Glen.

We have a mix of resources where some of our equipment is run over a 24
hour
period, but the people and other equipment will be utilized within the
standard 8 hours workday.

If project can't handle the use of multiple calendars, then why does it
know
that the duration is 4 days when displaying the Gantt chart bars?
Project's
inability to handle multiple calendars comes as a shock and
disappointment
in
what I would consider a pretty common scenario.

Approaching the problem another way, if the calendar options were set
so
that "Hours per day" were 24 hours rather than the default 8 hours,
would
Project schedule tasks properly since working time of the
8-hour-per-day
resources were restricted by their Standard calendars?

--

-Mike


:

Hi Mike,

Welcome to this Microsoft Project newsgroup

If all your work is on a 24 hour basis then you should change the
working
hours: see FAQ Item: 5. Default Working Hours. However, I suspect
this
is a
one-off and Project cannot handle effectively different calendars - it
has
to pick one to show - the standard project calendar based on an 8-hour
day
as you discovered. Don't forget that although the Duration shows 12.5
days,
the Work is correct at 100 hours. You'll have to live with that.

FAQs, companion products and other useful Project information can be
seen
at
this web address: http://project.mvps.org/faqs.htm
Hope this helps - please let us know how you get on

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



I have a Fixed Work task that will take 100 hours of Work. The
resource
is
a
piece of equipment that is allocated at 100% Units on the 24 Hours
Base
Calendar.

The Duration, however, is calculated at 12.5 days in the Task view,
which
is
what you'd expect for the Standard Base Calendar (8 hours/day). The
Duration
should be just over 4 days for this resource at 24 hours/day, which
is
how
it
appears in the Gantt chart (blue bar extends over a four day
period).

What could be causing this? Thanks.