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Work amount , quantity and resource

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Ahmet Tuter
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I want to confirm something.

Lets say we have 1000 lf of conduit to install. One labor installs 200 lf conduits a day. Lets call him worker 1. So it will take him 5 days to complete.

Now if we had only him as labor, the duration of this task is 1000/200 =5 days.

And the work amount is:

Work = duration x units,

so,

5 days x 8 hours x 1 labor = 40 labor-hours (manhours)

Now this comes to man-hours. Why do I see work amount as hours in many places? This is my first question.

 

Then my second question... let's say we have another labor. Call him worker 2. He installs 250 lf conduits per day. So he takes 1000/250 = 4 days. Now the work amount will be 4 days x 8 hours x 250/200 = 40 man hour again correct? So in other words, it is as if we have a resource worth of 250/200 = 1.25 times of the previous resource now, and that is how we must put worker 2 into equation right? And this way the total work amount doesnt change because we are talking about the same 1000 lf of conduit after all.

 

 

Replies

Mahendra Gupta
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Read below articles to understand the work hours allotted and hours calculated in Projects like FTE, Man Hours etc. 

https://www.saviom.com/blog/fte-vs-hours-what-should-you-use-and-when/

Also, you can read about how workforce planning can prevent the employee burnout here: https://www.saviom.com/blog/how-does-workforce-planning-prevent-employee-burnout-down-the-line/

Rafael Davila
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Rafael Davila
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When resources are limited not always the team with more resources is the choice that will yield shorter duration schedule.  While usually there is an optimal crew size making it the only option is not always a good idea. A good model will make the right choice as resource demand and availability changes when schedule are updated.
2021-05-09-10-45-18 multi-resource A selected, a smaller team.
2021-05-09-10-43-42 multi-resource B used as A was deleted as an option.

Never overlook the possibility of using multiple similar teams on same activity. Always look for idle resources reports, too many idle resources means there is a possibility schedule can be improved. This shall be considered in delay claims as cookbook approach is usually wrong.

2021-05-12-06-35-08 multi-resource A for activity 1 for team 1 assigned for 4.25 days and for team 2 assigned 8.25 days yielding a substantial reduction in schedule duration and not a sigle hour of idle resources.

Rafael Davila
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Effort is different to work they are quantified using different units of measure, that some effort was done does not means work was done. Man-hours is a measure of effort. It is convenient to use multi-resources to define crew production rates. When the production rate is non linear to the resource quantities we simply define the alternate crews each with their own production rate as a multi-resource and set them as belonging to a same skill.

Patrick Weaver
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Hi Ahmet, 

For every activity, the fixed point is the quantum of work to be achieved (your 1000 linear feet) - this does not and cannot change!

The variable is the production rate which is a factor of the capability and number of resources applied. For example, the production rate of a team of 2 people may be 50 lf/hr, one person only 20 lf/hr (a team is usually more efficient but not always).

The duration of the task is a result of the quantity divided by the production rate 1000/50 = 20 Hrs = 2.5 days (at 8 hrs/day) for the team; otherwise, 1000/20 = 50 Hrs = 6.25 days for a single person. 

That is the 'real world'. 

However, most scheduling software assumes the duration is fixed which creates a lot of anomalies; different people and different software have various ways of working around this structural fault in CPM software.  For more on this see: https://mosaicprojects.com.au/WhitePapers/WP1052_Time_Estimating.pdf

Ahmet Tuter
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Thanks guys for all the input but I am gettig confused with the flood of information. My two questions in my original message were:

1-For work we use manhours, not hours correct? - And as far as I understand from here, the answer to this is YES. I ask because I saw in MS project that the work amount is given as hours.

2-The work amount is the same, it doesn't change, which is 40 manhours, correct? So my calculation for worker 2, writing him as 1.25 and saying 8x4x1.25 = 40 in my original question is also ok? I especially need to confirm this one. If you did, I am sorry that I missed it

Rafael Davila
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To fix resource productivities and activity durations is not always a good idea.

Rafael Davila
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Rafael Davila
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How would you level the following schedule?

There are 3 resources of Skill A, quantities assigned, resource productivities and activities volume of work, as per image. Activities and resources work on same Calendar A.  Note same resources can have different productivities for different activities, in this simple case Activity 2 productivities are reduced by 20% because of work conditions. After leveling duration hours, quantity distribution, volume of work by resource and resource hours will be adjusted as necessary. If any activity is delayed for whatever reason the resource leveling algorithm will take care of selecting the distribution that will look for shortest schedule duration at a click of the mouse.

Easy, only 3 activities and a single resource skill all working on the same calendar.

2021-04-28-13-59-30

2021-04-28-14-00-05

Zoltan Palffy
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Vlad I agree that is why I said that his company should have a standard installation rate.

Zoltan,

In this case an amount of work is an initial information, manhours depend on the productivity of assigned resources.

Planning resource assignments we take into account their productivity on activities of different types and try to optimize project schedule. Using wrong productivities we can miss an opportunity to create better schedule and to finish jobs earlier or cheaper. Decision who must do what depends on resource availability and capabilities.

Our customers usually create their own internal norms and use them when develop project schedules.

Zoltan Palffy
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1. Yes everything in the world is based on manhours NOTHING get made or installed wihout using mahours. 

2. your company should have a standared rate based on past history. You can also use industry standars for installation rates. You should base the installation rate of the typical type of work being performed not the individual worker. For example what if the faster installer gets switched to work in a different location ? Do you change his duration to 5 days for the slower worker and then reduce the duration for the work location that he was switched to ? What if he is moved to a different project. ?

USE standard installation rates if worker #2 gets done faster so be it you just saved some time on the schedule. 

Ahmet Tuter
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Thanks... so my calculation when calculating the work amount for worker 2 is also correct , and the total work for installing 1000 lf conduit must remain the same, because bottom line is, it is the same task right?

 

And what about the units of work? Hours or man-hours? or both can be?

 

Rafael Davila
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Exactly, depending on resource assignment, availability and their production rates the activity duration might change.

Scenario 1

  • Availability: 3 ea - with different productivity each resource
  • Assigned:   2 ea - no activity is competing for the 3 available resources so the highest productivity resources are assigned.
  • 2021-04-26-12-48-41

Scenario 2

  • Availability: 3 ea - with different productivity each resource
  • Assigned:   3 ea
  • 2021-04-26-12-47-22

If your software does not help you will have to adjust the activity durations manually. It gets complicated when resources availability and demand change with time and so the durations of the many impacted activities.