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Calendar days vs Work days

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Julia Chaffin
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Wondering what others views are on using calendar days vs work days in a schedule?? Does anyone see a real difference between the two?? What are the advantages and disadvantages??

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Zoltan Palffy
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when using more than 1 calendar the foalt valuse wil be different.

Some things such a as contractual milestones areare usually stated as having to be completed in X number of calendar days after NTP.

Planning you work duration in calendars days when you actually only working working days will not show the planned manpower requirement correct nor will it show the proper cash flow projections.

Best bet is to plan the work durations in working days. This way the manpower forecast and cash flow forecast will be accurate.

Philip Jonker
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Henk,

The point is that the calendar is eternal, but the durations should remain the same, unless you decide to take measures to correct this, such as increasing working hours or resources, etc

Regards
Henk van der Heide
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Philip,

I think building contingencies into the duration is as good (or as bad) as contingencies in the calender. However if the planner knows what he’s doing it shouldn’t be a problem.

The advantage of the calander thing is: When you should make a recovery plan you only have to change the calender for instant change 8 hrs working to 12 hours working. Then you have your basis for your acceleration plan.
When you use the duration way you need to adjust al the critical durations.

Kind Regards

Henk
Henk van der Heide
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Philip,

Betekend dit dat we verder kunnen gaan in het Nederlands

Groeten,

Henk
Philip Jonker
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Henk
PS, Donner en Bliksem hebt julle nou al te luijbuisen, from the Scheepsjongens de Bontekoe
Philip Jonker
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Hi Henk,

It is important to put the right amount of float into a programme, but, the calendars is not the place to do it, contingencies should be built into the durations, this includes things, like learning curves, raindays, etc. If you allow everybody to build contingicies into calendars, you would end up with zero working days, or a million calendars.

Regards

Philip
Henk van der Heide
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I usualy have a 8 hours work calander. Yes this means that for the "normal"work you have 16 Hours of non work time.
for construction this time is often used for speeding up programms en activities that should take place when now one else is at side. However i think its important to be clear to the project team about the calanders that have been used because it gives the project manager a feeling about the "float"in the schedule.

Kind Regards

Henk
Philip Jonker
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Hi Julia,

Been through this argument on multiple occasssions, about 5 times today. Everybody wants to build as much float into their project as possible. The question is where to stop.... And this is where I will start another argument, do you allow for the the contingincies in your calendars or duratiohs????? This is an interesting question, as you may have to achieve 10 000lm/day and you have 200 000 so you you have 20 days, do you only allow 14 days a month or 21 days? If it is earthworks or tunnelling?
Gary Whitehead
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Julia,

If you are referring to the difference between ’Week 1’ and ’1st Jan’ as Nigel has assumed, then his answer is a good one.

If you’re talking about the difference between having a week-long duration meaning 5 (work) days or 7 (calendar) days, then see below:

Definitely use work days, and not calendar days. There’s a number of reasons for this. Here are some of them:

1) Using work days instead of calendars enables you to accurately & easily reflect in the programme different tasks having different working calendars (eg the design may be done on a 5-day week, and the construction on a 7-day week)

2) Even if all of your project tasks will be standard 5 day & 40hr week, you may still end up having to work weekends to hit slipping deadlines, in which case see above

3) Certain tasks / milestones, eg funding approval, may only be able to occur on a set day of the month. If you use calendar days and not working days, you would need to alter your lags/durations to project an accurate date, each time the project slipped.

4) If you use calendar days and not working days, it becomes more difficult to get meaningful reports on resource utilisation & forecasts ("Brian, you only booked 4hrs against my project last week, and you’re supposed to be on it full time!" "....it was Christmas...")
Nigel Winkley
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Julia

The main, useful, difference I find is for tendering type programmes where, say, you are not sure of the actual start date but do know the durations and logic.

If you use a normal calendar date then people can assume that you are definitely going to start on, say, 3rd July 2007.

If you use the week numbers, then it shows a pure schedule that, whilst having durations and times, does not show the definitive start dates. It does give people the overall length of the project, when things are going to happen, relatively, so they can see that 10 weeks after you start you are going to assemble the steelwork - or whatever. Exactly when that 10 weeks is, depends upon all sorts of things but they get the overall idea.

Hope this helps

Cheers

Nige