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Consumable resource leveling capabilities of scheduling software

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Rafael Davila
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Does this mean these the software can level consumable resources, or they just make a warning of some over allocation?

Oracle Primavera P6:

  • Adding Resources - Use this task to add resources to the resource pool. Resources include the personnel and equipment that perform work on activities across all projects. Resources are generally reused between activities and/or projects. Resources can be distinguished as either labor, material, or nonlabor. Labor and nonlabor resources are always time-based, and material resources, such as consumable items, use a unit of measure you can specify.

Asta Powerproject:

Deltek Open Plan:

  • http://www.fplotnick.com/CPMinConstructionManagement/DeltekOpenPlanManuals/DeltekOpenPlan35UserGuide.pdf
  • Consumable – An individual resource that can be consumed or “used up” over the course of a project. Building materials such as bricks used in a construction project are a typical example of a consumable resource. Units of consumable resources that are not required during one period of availability are carried forward to the next period. For example, assume that the availability of bricks is defined as 3,000 units on a particular day. If the requirement for the bricks is only 2,000 units on that day, Open Plan carries forward the remaining 1,000 units to the next day.

To figure it out we can try resource leveling the following consumable resource scenario [Bricks/Cement&Sand] that is unfeasible unless all are leveled or constrained.

Materials-prior-to-leveling

Materials-prior-to-leveling-02

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Rafael Davila
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As Vladimir said before – “Manpower shall be leveled but it does not mean that the best solution minimizes idle time of all trades. Fast execution of the critical activities minimizes project duration and indirect costs. Additional indirect costs may be higher than the cost of resource idle time. Resource optimization has constraints like certain target dates and criterion (usually overall project cost). So an approach that minimizes resource idle time does not always lead to the best solution”.

Say delivery 2 is delayed 3 days then what is best action to prevent delays?

Under such delivery schedule better allow for more than 2 bricklayers [16h/day], if availability is increased to 4 this will allow for more than 2 activities to be scheduled at the same time.

Resources-A1-2-3-Brick-Walls

https://www.mediafire.com/file/5yj45a11jsygvhs/Activity_Gantt_-_ResourcesA1.2_%5B3%5D_-_Brick_Walls.pdf/file

Rafael Davila
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Available video.

https://www.youtube.com/watch?time_continue=2&v=ACN6FcldoYA

Easy to verify if calculating materials/day and keep cumulative values to calculate inventory levels - please click following link for a PDF you can download.

Or take a look at the following worksheet.

Anoon Iimos
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IMHO, The difference between Engineering, Construction and Project Controls (Planning and Scheduling in particular), is never understood until today. WHY? Simply because the process is always forgotten. For example: Engineering has "Basic Engineering" and "Detailed Engineering"; and going forward to "Construction Operations", you still need to develop the so-called "Shop Drawings" and "Method Statements" (which are basically part of detailed engineering). Now, let me ask everyone: How do you usually develop a certain "Construction Schedule"? Or where do you base your "construction schedule" from. Perhaps 99.99% of you will say: You just copied your schedules from previous projects or you were just given samples of similar projects from peers. Now, still wondering why your schedules are always wrong or never followed by people in the fields? The fact is: To develop a detailed construction schedule (material resources included - of course without even mentioning leveling) is only a DREAM! Most of the time, the only thing a scheduler can do is make a guess or assumption. So what do you think would be the output using a software (and resource leveling for that matter)? Kindly check your bins please?
Anoon Iimos
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I'm not sure why you had a debate on "consumable materials" (bricks installation in particular), while keep on giving wrong or misleading examples. This is the problem with "sample only", considering theory. It always lead you to believe that what you are doing is correct. However, when the time you come to realize it (or hindsight), you might start to believe that what you did was totally incorrect. As "bricks installations" are not just bricks and mortars. Of course you will need scaffoldings, crane if you are working on high rise, rebars where necessary, stiffiner columns or beams, portable mixer for mortar if manually mixing, or ready mix supply, etc.,etc.,etc. Please remember that theories are always different from realities. Or nothing is certain in real world. So again, Forget about using "Retained Logic Only"!
Rafael Davila
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Among the many things that make-up a good schedule is that it can model how a good PM would schedule the activities, this applies to consumable resources as well.

In many scenarios materials shall be installed as soon as possible no matter if the activity becomes intermittent.

In some cases it makes no sense to wait until all activity materials are delivered; in desperate situations, and in not so desperate, looting might happens, better install the bricks ASAP. 

In the case of St. Martin, after the hurricane I do not believe an islander would be so foolish as not to install every single brick, piece of wood or many other materials ASAP.  On the other hand some activities such as cement plaster shall be scheduled to be continuous in most instances.

An islander would install bricks ASAP, he will never wait for the activity to be continuous.

 

Rafael Davila
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Financial constraints are a type of consumable resource that must be leveled in order to avoid disruption of your portfolio.  Cash flow is unknown before resource leveling; a good model shall calculate cash flow based on how activity moves, incomes (supply) as well as expenses (consumptions) are not fixed with time. Not all cost components represent cash flow, it is essentially a cost center compose of several cost components.

The model shall be able to replicate real world scenarios. For example activities create the need to rent a piece of equipment as well as its release, they define the rental period as activities move. This piece of equipment pays rent no matter if idle or not during the rental period, but when in use it will consume some materials that have some costs. The resource leveling shall consider all consumable, renewable and financial resources as they happen.

Rafael Davila
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ORIGINAL CHALLENGE - It is just 3 Brick installation activities, 2 cement plaster activities, 4 delivery activities, 3 consumable resources (bricks, cement & sand) and 1 renewable resource (bricklayers) with an availability of 3 assigned in different quantity to the installation activities.

SOLUTION: 

Materials-after-leveling

Materials-after-leveling-02
 

Best Regards,

Rafael

 

Hi Johanness,

I do not understand your remark about the tone of our discussion.

I did not understand your method and suggested to show its application on the simple schedule that you created with minimal change of initial data (4000 bricks per first two weeks and 7000 on the last week instead of 5000 each week).

What is wrong with my request?

Rafael Davila
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To all,

Because Johannes never posted the XER file where multiple activities rolled up it is obvious his solution was by creating many sub-activities for every installation activity. I agree “You’ll only see it once you understand it."

Asking for the XER file of a schedule Johannes have already done is not too much asking, in no way makes the discussion a hard toned debate.  Impossible to understand it if the information provided is not enough.

Asking for clarity on what Johannes is doing in no way makes the discussion a hard toned debate.

Asking to follow the requirements of my challenge in no way makes the discussion a hard toned debate.

I am not surprised few are willing to de debate on the subject of leveling material resources, many do not resource load their schedules.  Those who do if using P6 know P6 resource leveling capabilities are very limited and therefore much manual manipulation is required, not a pragmatic approach in complex schedules.  As soon as the schedule becomes a bit complex they run away.

I am not surprised Johannes quit as to avoid following the conditions of my challenge, something he never did.

I am surprised Johannes never provided the XER file so that we can see what he was doing.

The conclusion is:

P6 cannot level the condition for installing the brick material as required, a common condition in my jobs.

P6 can only deal with simple scenarios usually by much tweaking such as by creating many additional activities.

Best regards,

Rafael

Johannes Vandenberg
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Hi all

Hi Raphael

I now begin to understand why nobody, except myself,  is willing to de debate with you on the subject of leveling material resources.

I have studied your responses that I am surprised about the tone of the debate, and I am not going to spend any more time on this subject.

The original question was

Consumable resource leveling capabilities of scheduling software

Does this mean these the software can level consumable resources, or they just make a warning of some over allocation?

Yes, The scheduling tool Primavera P6 is capable of efficiently managing resource optimization, regarding resource leveling and resource smoothing techniques as I have demonstrated in my posts.

The graphs are still available on my blog

 https://primavendum.com/leveling-resources

I would like to close this debate, from my part, with a quote from Famous Johan Cruijff soccer player and Philosopher.

“Je gaat het pas zien als je door hebt””

“You’ll only see it once you understand it."

Regards Johannes

Rafael Davila
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I have adhered to all the constraints in this challenge.

  • I am not sure you have adhered to all the constraints in this challenge.
  • An essential requirement of my challenge is to plan for installation of bricks ASAP, no unecessary delay is allowed.
  • Your model looks like very conveniently misses to plan for installation of bricks ASAP.
  • Please make XER file available, I am still not able to see your schedule details.
  • Comparing resource leveling details with a second shift against a schedule without it makes no sense. Your schedule finishes on Nov 19, the schedule with a second shift finishes on Nov 2. If comparable then your model would be disastrous.
  • I cannot understand how installation bars are rolling up, I need the details to follow what you are doing.
  • I cannot understand why you are (or might be) using different activities to represent a single activity.
  • I need to see the summary bars expanded to see the details; it looks like you added many activities to force some leveling.

As I said before:

  • My challenge requires to allow for interrupted bricks installation and install all bricks ASAP, not so for cement plaster.
  • No doubt we can disagree on whether allowing for interruptible activities or not.  For purposes of my challenge a requirement is to install all available bricks ASAP.
  • We consider intermittent scheduling for bricks installation desirable; otherwise a simple change of the condition for activity to be splitable as shown in column 10 of my figure, from Yes to No would be enough to get such undesirable schedule. At home we would never delay installation of materials such as bricks. Among other things we want to accelerate the billings.
  • I agree the model to be good shall be leveled at a single click of the mouse.  Necessary for Monte Carlo where you cannot make changes for every resource leveled iteration.
  • I would appreciate if you follow the requirements of my model with a calendar that includes work on Saturdays, such calendar is so common at home that it cannot be overlooked. I would appreciate if you post for download the XER file for you posting of Mon, 2017-08-28 17:48. Otherwise the conclusion would be P6 cannot handle such simple scenario, unless by manual methods, unless going to extreme workarounds like creating many activities, by brute force.

Best Regards,

Rafael

Johanness,

I want to return to the original simple schedule where bricks were supplied not in 5000/week speed but 4000 at the first and second week and 7000 at the third week.

There are two bricklayers available with 50 bricks/hour productivity. Work week consists of 7 days and 7 hours per day.

Two bricklayers are available. Each activity can use 1 or 2 bricklayers.

Activity volumes of work are the same as in initial example that you suggested.

Now for unknown reason I don't see your initial images but these volumes (number of bricks) can be seen in my response.

So just change the supplies.

I want to see the feasible schedule where both bricks and bricklayers were leveled.

Johannes Vandenberg
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Hi All

Hi Raphael and Vladimir

I have noted your comments

I have adhered to all the constraints in this challenge and designed a scheduling model that will work and I ask you to look again at the images I have provided and you will find the answer. Do you concur that mine is better leveled of do you have any other opinion? You can see the histogram for the 3 bricklayers.

No manual leveling, no constraint One click of the mouse, after the designing of the model.

For illustration see the next images.

Materials_Leveling_with_a_2nd_Shiftrev

Overall_Picture_with_comments

Regards Johannes

Rafael Davila
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Vladimir,

If one resource is idle it can be used in another activity, so at times an activity can use one bricklayer and another times can use two bricklayers or more, as done at construction jobs, a no-brainer. 

Such strategy usually results in lower level of staffing and a greater reduction of idle time than any other strategy.

Best Regards,

Rafael

Manpower shall be leveled but it does not mean that the best solution minimizes idle time of all trades. Fast execution of the critical activities minimizes project duration and indirect costs. Additional indirect costs may be higher than the cost of resource idle time. Resource optimization has constraints like certain target dates and criterion (usually overall project cost). So an approach that minimzes resource idle time does not always lead to the best solution.

Resource leveling shall take into account all constraints (both renewable and consumable resources, space, financing). The number of available renewable resources does not change from one week (day, hour) to another. If materials are supplied with different speed (intervals) we will not hire and fire bricklayers each several days. So I would like to look at scenario when 4000 bricks were supplied on the first week, 4000 on the second week, and 7000 on the third week with continuous and splittable work patterns when only two bricklayers with 50 bricks/hour productivity are available and each activity can use one or two bricklayers. Let's suppose that work calendar is 7 days/week and 7 hours/day.

Rafael suggested rather complex scenario, I want to understand this very simple one.

Rafael Davila
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Johannes,

Yes, I have uploaded a large image and hope that this is better readable.

  • I downloaded it and is still unreadable. The missing information is still missing.
  • Instead of using “print-screen” I get better images by printing a report into PDF, then using my PDF editing software I export the PDF to jpeg, finally I crop the jpeg and post the image.  For Powerpoint png yields better results.
  • Please post the XER file of the model you already have.  It does not make much sense not to use XER files.
  • That would make everithing easier and will solve most of the basic issues.

But I also conclude that at the same time the manpower histogram for the bricklayers is not adequately leveled.

  • Please be specific, we can verify hour by hour the histogram.
  • We level resources not effort; this could yield unfeasible leveling if using partial workloads.

Cpm schedules - resource quantities and workloads from Rafael Davila

 

I consider that the labor resources should be leveled or smoothed taken into account the constraints on the material delivery and go for the best-suited option.

My model, as you can see, is designed to have a permanent un interrupted work process for the bricklayers, with a minimum of “lost time.”

  • We are talking about my specific model not yours.
  • I took my time with your model, I deserve you do the same and follow my model requirements.
  • My requirement is to allow for interrupted bricks installation, not so for cement plaster.
  • We consider intermittent scheduling for bricks installation desirable; otherwise a simple change of the condition for activity to be splitable as shown in column 10 of my figure, from Yes to No would be enough to get such undesirable schedule.
  • No doubt we can disagree on whether allowing for splitting or not for all or just a few. For purposes of my scenario the descision is to allow splitting on some activities.  At home we would never delay installation of some materials such as bricks.  I would appreciate if you follow the requirements of my model, otherwise the conclusion would be P6 cannot handle such simple scenario, so common at home, unless by manual methods, by brute force.

Once again thanks for your cooperation to this discussion, without you it would probably be deserted.

Best Regards,

Rafael

Johannes Vandenberg
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Hi All

Yes, I have uploaded a large image and hope that this is better readable.

Raphael, I have studied the outcome of your leveling efforts, and I have the following comments.

I conclude that you show nice run-down curves for the consumption of the consumable resources. But I also conclude that at the same time the manpower histogram for the bricklayers is not adequately leveled. I consider that the labor resources should be leveled or smoothed taken into account the constraints on the material delivery and go for the best-suited option.

My model, as you can see, is designed to have a permanent un interrupted   work process for the bricklayers,  with a minimum of “lost time.”

Regards

Johannes

Rafael Davila
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Johannes,

Please be reminded your images are unreadable.

A lot of information is missing as I can only see many summary bars but not the activities. 

  • I cannot see the activity start and finish dates of the activities so I can test the schedule using simple start not earlier than constraints and force the model to use your dates and verify how the inventories move with time if using my software.
  • Are you using milestones to assist you in manual leveling and using the software to make the checks in the same way I would verify your schedule? It looks like date constraints are driving the leveling.
  • The model is not using activity splitting as required.  It is not a good idea to keep uninstalled bricks when they can be installed earlier. Intermittent installation of bricks is desirable even if it ends up with same project duration.
  • I cannot see late bars.
  • I cannot see resource quantities.
  • Can you post the XER file?  I do not have P6 but I can read it.

I saved your image but it is blurred, I could interpret a finish date for installation activities of 19-nov-13 12:00.

Can you please post some downloadable images that are not so blurred?  You can click on my image and save it; if you zoom the image it will still be readable.

I cannot understand why you created a separate activity for every delivery item, in real life each delivery can consist of many items, each delivery with different items and quantities. It is not a pragmatic approach.

Have you tried the same model if adding a night shift, a common scenario? So easy just add the second shift, everithing else remains equal.

Best Regards,

Rafael

Johannes Vandenberg
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Hi all

Here is my leveling overall picture  for the example Raphael suggested

Overall_PictureOverall_Picture_website src="https://s20.postimg.org/pompvpyvx/Overall_Picture_website.jpg">

And the resource assignments Resource_assigment

Levelling_specification

Regards Johannes

Rafael Davila
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Your images are unreadable.

Rafael Davila
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Johannes,

We might consider adding a night shift that will expedite installation after last delivery; this is a common approach we use to deal with tight schedules. Night shifts mean no overtime and not too many people working together when space is limited.

These are interesting as they will not necessarily work on same activity as shift 1.  Latter on we can get into more complex assignments that will make calculation of consumables more challenging.

Delivery 4 is critical; other deliveries are not and might be delayed within its resource leveled float values.  Because we are planning for some activities to be intermittent the same as early bars will be intermittent so do the late bars, here tabular reporting is a necessity as start and finish float will not be enough to tell the whole story.  Float values must also be verified as to make sure P6 float calculations and late delivery dates make sense under several shifts.

For brick installation you do not plan for work fixed for team, it happens on first come basis, therefore distribution for volume of work and activity duration is dynamic, this is most common case scenario.  For installation of bricks, a consumable resource, consumption follow the bricklayers.

Best Regards,

Rafael

Rafael Davila
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Johannes,

Enjoy your golf.

Thank you again for your time. I will be waiting for your reply to the challenge.

Best regards,

Rafael

Johannes Vandenberg
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Hi Raphael

Nice challenge. Play golf today. get back with you tomorrow

Regards

Johannes 

I also don't understand 700 bricks per day condition.

If 5000 bricks are available they may be consumed in one or two days if some activities require this amount and the number of bricklayers is sufficient. It does not make sense to delay an activity if it can be done faster.

I also don't understand 700 bricks per day condition.

If 5000 bricks are available they may be consumed in one or two days if some activities require this amount and the number of bricklayers is sufficient. It does not make sense to delay an activity if it can be done faster.

I also don't understand 700 bricks per day condition.

If 5000 bricks are available they may be consumed in one or two days if some activities require this amount and the number of bricklayers is sufficient. It does not make sense to delay an activity if it can be done faster.

Rafael Davila
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Johannes,

Thanks for your clarifications. By looking at your last post with the exception of A1010 with an installation of 8 bricks what you are showing look like balanced for an availability of more than 700 bricks per day.  I could never understand the 700 bricks per day you mentioned; perhaps you meant 700 bricks per day per bricklayer.  The image showing all activities in tandem got me confused.  

Your sample schedule looks like tailored to be a simple schedule for purpose of illustration, so simple it cannot be used as a reliable test.  Among other considerations production rate varies depending on the difficulty of the wall, it is not the same installing brick at low height than installing high walls. The sample schedule you provided does not includes such common scenario.

I will believe P6 can reliably level consumable resources if you show it by modeling something a bit more complex; something with multiple consumable resources, with different production rates, with different delivery amounts and allowing for intermittent work on selected activities, a workweek with fewer work hours on Saturdays because of noise regulations, the way it happens at our job-sites.

Johannes Vandenberg
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Hi Raphael

Thanks for your response but I consider that the leveling of material resources is not flawed in P6 as I have explained in my previous post.

First of all, let's go back to the original subject

Consumable resource leveling capabilities of scheduling software

Does this mean these the software can level consumable resources, or they just make a warning of some over allocation?

Oracle Primavera P6:

I have responded that labor and labor resources can be leveled and provided 2 examples. One for the labor and one for the materials. Both consisted of 3 screenshots, e.g., Unleveled, level specification and for the leveled condition.

This is what I have responded to your comments

So, as you can see in the examples, the histograms in the unleveled position are different because one is for bricks and the other is for labor man hours. So, what’s next?

I have first leveled the material resource, bricks,  As you can see, the completion date is established after at 04-Oct. 2017  

Secondly, I have leveled the labor resource ‘Bricklayers.' As you can see, the completion date is now 20-Sep. 2017

What one of the features of resource smoothing is that we sometimes are not able to optimise all resources.

You have to make choices, streamline the material delivery or optimise the output of the bricklayers. What I could have done is to match the availability of bricks exactly to meet the production rate of the Bricklayers, but that would have defeated my purpose of the debate.

I have designed the example in such a way that a choice would be obvious to make. Go for the date of 20-Sep. 2017 or for the completion date of 04-Oct-2017 or find the other solution.

Would you agree that material resources can be leveled in Primavera P6?

My response now.

Apparently, you have made a choice, see above,  that the bricks delivery should fit the output from the Bricklayers 16 hours/day, and this would put the completion date at 20 Sep. 2017 and not as Oct. 04-2017 for the bricks. I have not made this choice because. It is obvious that this could not be correct because of the rate of supply of 700 bricks a day, as you are have demonstrated.

If I would make the choice that the leveling priority for the bricklayers has priority above the supply of materials and that these are to be speeded up to match the output of the bricklayers so that they can, without interruption, complete the work at Sep-04-.

So I have modeled the schedule to reflect this situation, and you see the outcome hereunder.

 

Histogram_leveled_for_Bricklayers

Activity_resource_assingment

Histogram_for_Bricks_leveledl

Regards Johannes

Rafael Davila
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P6 materials leveling is flawed, materials cannot be leveled as if renewable resources. 

IMAGES - LOST - Sorry the images got lost - in order to reconstruct them I will need clear P6 images or XER file.

Resource types: Renewable and consumable resources

Consumable resources (or non-renewable) are not constrained on a periodic basis but rather have a limited consumption availability for the entire project. Typical examples are money, raw materials and energy. Usually, the overall project costs are limited and pre-defined in a total contract price. Their consumption is not renewed as is the case with renewable resources; but instead, these resources are consumed when used.

Doubly constrained resources are constrained on a periodic basis, similar to renewable resources, as well as for the total project duration, as with the consumable resources. An example is a total budget with an extra restriction of a maximum limit per period.

We are talking about consumable resources not about a restriction of a maximum limit per period.  To put a limit per period but not taking into consideration the availability makes no sense.

If you want to double constraint any consumable resource to a supply schedule and a maximum consumption limit per period then just add a renewable resource for this purpose and then level all consumable resources and renewable resources at the same time.

Rafael Davila
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BTW financial resources are consumable resources that must also be leveled.

Rafael Davila
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Even if delaying the start of some of the installation activities for next day as to be safe in my claim because I could not read time of day the schedule is still not feasible.

If fractional consumption is not allowed you can specify discrete consumption, this I do for items such as air conditioning units, plumbing fixtures and the like. It is not a good idea to split in half a water closet 1/2 for an installation activity the other half for other installation activity and wait for next delivery to glue the halves.

Hi Johannes, thanks for te explanation but I still do not understand your approach. My conclusion that your schedule is not feasible is based on the analysis of the bricks flow - there are periods when bricks consumption exceeded bricks availability.

I do not understand your two stage process. Resource leveling shall take into account all existing constraints simultaneosly and produce the schedule as short as possible.

Rafael Davila
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About volume of work and production rates.

They go hand in hand with multi-resources and skills. 

Johannes Vandenberg
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Hi Vladimir

No, Vladimir, your understanding is not correct. I have labeled the bricklayers as labor resources and the bricks as material resources and that is in line with the glossary of  PMI’s PMBOK®Guide.'Resources are human resources, equipment, services, supplies, commodities, materials, budgets or funds.

I did not understand what did you do next.

As I have explained that in my previous post.

I have designed the example in such a way that a choice would be obvious to make. Go for the date of 20-Sep. 2017 or for the completion date of 04-Oct-2017 or find the other solution.

You statement

 Both schedules that you got are not feasible.

I consider this statement unfounded and wrong. Can you explain why not? Do not use your interpretation of my schedule, as you have tried in a previous post, but use my original that I have posted but regretfully disappeared from the post. The screenshots are still available on my blog.  https://primavendum.com/leveling-resources

Besides, I do not know how to enter resource productivity in P6. Please explain.

Neither do I. Can you explain how this should be done and what are the benefits..

Regards

Johannes

Johannes,

if I understood your approach correctly you entered bricks as renewable resource (labor or non labor), leveled the schedule for bricks and for bricklayers separately and got different schedules as may be expected.

I did not understand what did you do next. Both schedules that you got are not feasible.

Besides I do not know how to enter resource productivity in P6. Please explain.

Rafael Davila
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You said - This is easy in P6. You can specify different max.time/time  Per calendar.

But what happens when the delivery is not fixed by calendar dates but by the finish of some predecessor activities?  This I use for modeling of Spatial Resources such as flying forms for elevated slabs that must remain in a building until structure is completed and last pour can be stripped. A common resource in all my jobs.

 

About skills I use them frequently in combination with multi-resources so that 2 low skilled resources might be automatically assigned in substitution of 1 highly skilled depending on availability.  Multi-resources are convenient when different crew size and productivity is not linear. Also because resource can have different calendars I use it to automatically replace one crew for another depending on the season the work is scheduled/re-scheduled. This is necessary for some Monte Carlo runs where you cannot make manual adjustments.

Johannes Vandenberg
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Hi Raphael

 

You said - In this smoothing process, I have used a max.units/ per time of 700 bricks. So the availability of the material resource is set at 700 bricks a day.

But what happens if the installation rates for different walls is different because their degree of difficulty?  On any given day the resources might be working at different rates, a common scenario in construction jobs.  Some days the maximum number will be 500/day, other days will be different. Will the P6 threshold be the same?

Yes, P6 will hold the max unit/day the same unless modified by the scheduler.

One more observation, the first batch is 5000 bricks. So, during the first week 5 days*700 bricks, are used. This leaves another 1500 bricks as a buffer in the event that they go faster than planned.  If slower than they remain at stock. Different productivity levels can be set at P6 by using skill levels.

I have never scheduled wall or bricks with exception of this example before but I assume that this is similar to the production rates for welders, some are fast some less. The foremen and supervisor are often doing great jobs in optimizing resources by selecting the best-skilled worker for the job.  

Regards

Johannes

Rafael Davila
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The following resource leveled schedule can showcase different production rates and what happens when planning for all installation activities allows splitting. 

Not leveled schedule showing materials overload.

BL001

Leveled schedule allowing for activity splitting.

BL002

Leveled schedule not allowing for activity splitting yields a longer duration schedule.

BL003
 

Rafael Davila
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Loaded Images are disappearing after some time. I this planned or an error in te CMS.

I suggest you use an external filehosting for images. 

  • I use Postimage.org
  • Post your images there and get the link.
  • Post the link on PP with rich-text disabled.
  • I mark the location of my images as XXX, YYY ... before disabling rich-text.
  • Then after disabling rich-text I paste the link to replace the XXX, YYY's ...
  • Then in the preview image placeholders will allow you to re-scale the images.

Latter will take a look at your reply, meanwhile please check my interpretation of the schedule, you know better how P6 works, I get confused with it.

You said - In this smoothing process, I have used a max.units/ per time of 700 bricks. So the availability of the material resource is set at 700 bricks a day.

But what happens if the installation rates for different walls is different because their degree of difficulty?  On any given day the resources might be working at different rates, a common scenario in construction jobs.  Some days the maximum number will be 500/day, other days will be different. Will the P6 threshold be the same?

You said - This is easy in P6. You can specify different max.time/time  Per calendar.

But what happens when the delivery is not fixed by calendar dates but by the finish of some predecessor activities?  This I use for modeling of Spatial Resources such flying forms for elevated slabs that must remain in a building until structure is completed and last pour can be stripped. A common scenario in all my jobs.

Cordially,

Rafael Davila

Johannes Vandenberg
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Hi all

Raphael

Hereunder you find the answers

 

Brick wall size      Production rateTotalDuration 
NumberLenghtWidthOpp.Bricks/m2TotalUnitsHours/piecehoursHours/dayDuration
Brick wall 1 52,512,575937,5no0,01211,2581,41
Brick wall 242,51075750no0,0129,0081,13
Brick wall 3102,525751875no0,01222,5082,81
Brick wall 46424751800no0,01221,6082,70
Brick wall 55420751500no0,01218,0082,25
Brick wall 66424751800no0,01221,6082,70
Brick wall 78432752400no0,01228,8083,60
Brick wall 810440753000no0,01236,0084,50
   187,5 14062,5  168,75 21,09
Brick delivery is 5000 bricks every  week on Monday      

1* Production rate is established ai 0.01hours/ brick for “normal.” walls

Production rate for walls around doors and windows 0.06 hours/ brick

For the example, I have used a combined rate of 0.12 hours/brick

In The Netherlands, you may order more than 20 sizes of bricks. I have assumed 75 bricks per  meter square

The purpose of the example I provided is to debate on the benefits of resource Optimization techniques. These consist of resource leveling and resource smoothing. The aim for the scheduler is to balance the resource availability or assignment is a better word, against the resource requirements.

In the example, I have used this two optimization techniques. For the resource leveling of the Bricklayers, I have used a max units/ per time period of 16 hours a day.  I have used as, in Raphael’s example ever week 5000 bricks delivered on Monday.

In this smoothing process, I have used a max.units/ per time of 700 bricks. So the availability of the material resource is set at 700 bricks a day.

So now we have the availability set for both the resources and these as I have called, ‘Leveling Specification.’ loaded in Primavera P6.

So, as you can see in the examples, the histograms in the unleveled position are different because one is for bricks and the other is for labor man hours. So, what’s next?

I have first leveled the material resource, bricks,  As you can see, the completion date is established after at 04-Oct. 2017  

Secondly, I have leveled the labor resource ‘Bricklayers.' As you can see, the completion date is now 20-Sep. 2017

What one of the features of resource smoothing is that we sometimes are not able to optimise all resources.

You have to make choices, streamline the material delivery or optimise the output of the bricklayers. What I could have done is to match the availability of bricks exactly to meet the production rate of the Bricklayers, but that would have defeated my purpose of the debate.

I have designed the example in such a way that a choice would be obvious to make. Go for the date of 20-Sep. 2017 or for the completion date of 04-Oct-2017 or find the other solution.

Vladimir, to answer you question.

An example supposes that bricks are supplied in individual speed (5000 per week). It is not always true in real life projects. More interesting is the case when supply is different each week, like 6000 on the first week, 4000 on the second week and 5000 on third. The original example is too simple. And intervals between the supply events may be different also.

This is easy in P6. You can specify different max.time/time  Per calendar. For example. 700 bricks in week 1, 1000. In week 2 and 600 over the next four weeks. The leveling engine will follow this.

Raphael,

Could you disclose your thought so that we can learn from you?

Webmaster

Loaded Images are disappearing after some time. I this planned or an error in te CMS.

Regards

Johannes

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Rafael Davila
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Vladimir,

I cannot follow the logic on Johannes schedule, he talks about production rate of 700 bricks/day but the activity durations do not match.

I guess given some time and with a lot of patience I could learn some P6 Frenchglish but if it cannot deal with different deliveries amount that would be unacceptable.  P6 jargon is not what we speak at the jobsite.  We do not say you have 16 man hours and two 8 hours days.  This can be interpreted as 1 person working 8 hours/day for two days or 2 persons working 4 hours per day for two days.  Even if you provide workload ratios we do not make the calculations on the job-site for thousands of resource assignments.

The reasoning behind P6 for leveling effort instead of quantity I find in error, quantity and effort are not the same; resource leveling for effort under partial workload can yield wrong results, at times on the optimistic but wrong.

It did not split any of the activities as my sample schedule would, so it is not a good example as to showcase what happens when activity splitting happens. In such simple scenario I would not expect much difference.

Let me know if I got Johannes model right, more interesting shall be Johannes response to my proposed scenario.  BTW a scenario proposed by the author of this discussion prior to his own I have taken the courtesy to model.

Once Johannes has it finished then we can try your suggestion of making brick deliveries as well as all others with more variations.  It shall be easy as it will only require changing some delivery values.

Best Regards,

Rafael

Rafael Davila
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Johannes,

  • What is the number of bricklayers assigned to each activity? 1 Bricklayer? 
  • How many bricklayers are available? 2 Bricklayers?
  • How many hours per day each bricklayer is assigned to each activity?
    • To say 16 units as if units mean man-hours and the activity takes 2 days this can mean 1 bricklayer working 8 hours per day, can be 2 bricklayers working 4 hours per day.
  • What is their production rate at each activity; it is not the same to install bricks on low interior walls than at high exterior walls?  Do you mean 700 bricks/day/bricklayer or 700 bricks/day/2bricklayers?  Same for all activities? 
  • Not everyone speaks P6 jargon, to some of us seems like Frenchglish.
  • In my example delivery of sand and cement varies per delivery, have you worked on it?

An example supposes that bricks are supplied in certain speed (5000 per week). It is not always true in the real life projects. More interesting is the case when supply is different each week, like 6000 on the first week, 4000 on the second week and 5000 on third. Original example is too simple. And intervals between the supply events may be different also.

Rafael Davila
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Johannes,

P6 calculations are unreliable but I believe in this case there is more than P6 unreliability.  A simple report that details on a daily basis how bricks are consumed and produced is enough to show if it is wrong.

As soon as brick inventory/cummulative/running values go into the negative there are no bricks to install !

Next figure displays how daily inventory is accrued per activity using standard software report.

  • SORRY THE IMAGES GOT LOST - Until provided with readable images by Johannes I cannot create them again.

Best Regards,

Rafael

Johannes Vandenberg
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Hi all

I have updated and edited the original post and added screenshots.

Please scroll down.

Regards

Johannes

Rafael Davila
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After making sure the start of project matches this is what I got it is not a good solution, is unfeasible. Easy to verify if fixing dates using start no earlier than constraints and look for overloads.

SORRY THE IMAGES GOT LOST - Until provided with readable images by Johannes I cannot create them again.

I tried Johannes example but got different results. If to use activity priorities defined by their order:

Bricks_with_priorities

 

If to ignore activity priorities:

Bricks

Rafael Davila
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I will assume bricks quantity is not proportional to wall area and will use non-labor units as to mean number of bricks.  It is weird to name quantity as "units", I wonder what is the name for unit of measure.  At home if you say 10 bricks it means quantity 10 and unit is bricks, 10 is not the "units", must be some combination of English and French.  I can figure out Spanglish but not Frenchglish.

 

Rafael Davila
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Vladimir,

The first image provided is the unleveled schedule and the second one the leveled schedule by Johanes.  Should be easy to create the model in Spider if readable and all required information is there.

Lets see how Johannes work out the scenario I submitted.

  • Please refer to updated post by Johannes.
     

I tried to look at Johannes link and found that my location is blacklisted.

So No comments!

Rafael Davila
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Johannes,

I do not use P6 I use Spider Project and the solution comes at a single click of the mouse. This afternoon after I return from other duties I will take a look at it. 

  • I can see from your images the brick delivery amount but cannot see the bricks amount for each installation activity, please provide this information, I am not sure if every M2 of wall requires the same amount of bricks as to linearly distribute the bricks amounts.
  • I can see from your solution image that the sequence of activities follow the activity order, that is suspicious as in most cases a good solution does not follow this order unless logically linked among them. 
  • Activity splitting is usually undesirable, but not always. Your solution seems like does not consider allowing for activity splitting which does not makes sense in brick installation, a condition set in my example. A condition that can be toggled on/off at a click of the mouse.  A condition that shall be applied at the activity level.
  • Your example looks overly simplistic as it deals with a single consumable resource instead of three.

I provided a simple schedule for the purpose of illustrating consumable resource leveling, please give us your solution to the sample schedule to see how good it can be. 

Thank you very much for your response, you have been the first and only person willing to deal with some numbers for consumable resources within this discussion.  No doubt it can be done with manual methods, but how good and reliable is of concern.

Best Regards,

Rafael

Johannes Vandenberg
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Hi all

I have updated this post and added screenshots

I appreciate the efforts of Raphael to demonstrate that resource management and more, in particular, the leveling of resources is crucial for the creation of sound scheduling models.

I use resource leveling and smoothing techniques all the time in my scheduling models but had not attempted to level material resources in Primavera P6.

Yes, you can level material resources in the same manner as labor resources as demonstrated in the 6 screenshots below

Fig.001 The bricks in the unleveled condition

4969
bricksunleveled_l.jpg

Fig 002  The leveling specification at a rate of 700 bricks per day

4970
bricks_leveling_specification_jpg.jpg

Fig. 003 shows the effect of the leveling of the material resource "bricks" on the activities. 

4971
bricks_after_leveling__.jpg

Fig 004 demonstrates the bricklayers in the unleveled condition

4973
unlevled_conditionjpg.jpg

Fig 005 Demonstrates the leveling specification for the leveling of the labor resource "bricklayers". The maximum units/  per time is set at 16 hours per day. 

4974
leveling_condition_bricklayers.jpg

Fig. 006 Demonstrates the condition when the resource "Bricklayer" is leveled

wysiwyg_imageupload::

4975
bricklayers_after_leveling_jpg.jpg

I trust this demonstrates that Primavera P6 can level material and labor resources

Please visit my blog with the link below and you see the leveling of materials and labor resources.

https://primavendum.com/leveling-resources

Regards Johannes

Rafael Davila
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http://archibaldassociatesllc.com/Problems_Methods_Tools%20of%20Advanced%20Constrained%20Scheduling.pdf

Project schedules must consider all existing constraints including resource, supply and financing restrictions. It should model real life work, taking into account working in shifts, activities where execution cannot be split, resources that may replace one another, and everything else that is taken into consideration by people that create resource schedules manually. If the software cannot consider real life restrictions, the schedules created by this software will not be practical.

MATERIALS LEVELING SCENARIO WITH ACTIVITY SPLITTING ALLOWED

Materials-Leveling-A2-12

Rafael Davila
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I published on August 11, 2017 at several discussions on LinkedIn the same scenario in the hope of getting at least a single response and within 3 days:

  • 937 views to my article
  • 739 views to Project Managers discussion group
  • 795 views to Planners and Schedulers discussion group

A lot of views, a lot of comments, not a single one dared to tackle the problem directly, all were evasives as if no-one within the scheduling community is capable of dealing with consumable resources.

Too many keyboard monkeys with pedigree, many with over 30 years experinece as Project Managers in their resume.

I hope some day at least a single one will dare to discuss the scenario without evasives, without BS-ing.

They all chicken out.

Yes Rafael, it can be done the way you suggested.

But when plan we expect certain probability of assigned resources. Actual productivity on the certain day may be different for many reasons. It does not mean that the rest of activity will be done with the same speed. In any case remaining schedule shall be adjusted after entering actual data.

Rafael Davila
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Vladimir,

I cannot imagine any serious scheduler that has never considered consumable resources constraints even if by using an abacus.

For the Great Wall of China consumable resources was a major concern.  The Great Wall over the ages used around 100,000,000 tons of stone, bricks, and mud.

A legend about the Jiayuguan Pass tells of a workman named Yi Kaizhan in the Ming Dynasty (1368BC-1644BC) who was proficient in arithmetic. He calculated that it would need 99,999 bricks to build the Jiayuguan Pass. The supervisor did not believe him and said if they miscalculated by even one brick, then all the workmen would be punished to do hard work for three years. After the completion of the project, one brick was left behind the Xiwong city gate. The supervisor was happy at the sight of the brick and ready to punish them. However Yi Kaizhan said with deliberation that the brick was put there by a supernatural being to fix the wall. A tiny move would cause the collapse of the wall. Therefore the brick was kept there and never moved. It can still be found there today on the tower of the Jiayuguan Pass.

I was hoping to find serious schedulers like Yi Kaizhan willing to take the challenge even when will be no punishment if they miss by 1 brick. I am starting to believe that P6, Ata Power Project and Open Plan schedulers will chicken out and run away from this discussion.

While someone shows up, if it ever happens, I would like to discuss with you some of the challenges I find when dealing with consumable resources using Spider Project.

When progressing the schedule I suggest before adding actual data to adjust deliveries for the updating period for planned to be equal to actual and fix delivery plan as Spider Project will not tolerate 1 missing brick. Then actual data input initially calculated by the software will need no adjustments. Please provide your comments and suggestions.

Best Regards,

Rafael

Rafael Davila
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For a jump start I am using an example where materials are assigned to activities, the simplest case of consumable resource assignments.  If the software cannot deal with the simplest scenarios I do not expect them to be able to deal with real but more complex consumable resource leveling.

Cannot be any easier.

Maybe I got it wrong but from the literature I understood they are capable of consumable resource leveling.  If I got it wrong all is needed is a clear statement they are not capable of leveling consumable resources.  I want to know if they have consumable resource leveling functionality. I want to know how good the leveling is if they have the capability to do so.

Rafael,

consumable resource assignment is no less interesting.

Materials can be assigned directly to activites as fixed amount, or per unit of time or volume.

But they can also be assigned to renewable resources (a car consumes gas whenever it moves) or to renewable resource assignmments (if we want to plan and to control material consumption by certain resources or contractors).

Materials can be consumed at activity start, at activity finish, during activity execution or using combination of these options.

If materials are not properly assigned their consumption planning is not reliable.

So it is interesting if scheduling packages can properly model consumable resource assignments.