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Anoon,
Im with Vladimir on this one. To plan a project properly you need to start with the scope and the logic, and then assign the resources required to deliver it in the sepcified time limit. To instead start with a defined list of resources, and then assign the activities would present the following limitations:
-Resources can be pulled from other projects, or assigned to them as required. But you wont know whats required until youve mapped out the scope & schedule. You cant optimise the project by adding or removing activities in the same way (unless you have a very generous client!).
-Activities have a logical sequence which must be followed (you cant fill a hole with concrete until youve dug the hole). Resources do not (you can utilise Jons time first, or Bobs. It doesnt matter). Defining the sequence of activities first ensures you satisfy this constraint. Defining the resources first does not have a similar benefit.
Cheers,
G
Yes Anoon,
we define a crew of resources (in Spider it is called multi-resource) and define the quantity (not hours!) of each resource in a crew (like 5 workers, one excavator, etc.).
Then you can select one or many tasks and assign multi-resource to all of them.
At any moment you may decide to change some crew (like to add one more worker) and these change will be automatically done everywhere that crew was assigned. If you changed driving resources then activity durations will become different (after schedule recalculation).
This is necessary for "what if" evaluations and useful during project execution. To change assignments manually is very time consuming in the real large projects.
Best Regards,
Vladimir
You need to assign the same task to many resources (or group of resources or a team)?
Then can you not define a crew or a team, say Team XXX composed of labor and equipment with a common and total unit say in hours, and assign this team xxx to yyy task?
I mean, assign yyy task to team xxx. ?
cheers!
No,
I always start defining the tasks to do and only then decide who will do these tasks. Assigning tasks to resources I need to assign the same tasks to many resources if there is a need in a crew and it is hard to control that all necessary resources are assigned to all tasks.
Best Regards,
Vladimir
Vladimir,
How could you say that its not pratical?
Imagine yourself as a "resource" that is tasked to defend Spider. Here, you exist first, your task comes later.
Again for example: You are a contractor with a maintained number of resources. Now comes your project, isnt it first that you assign this project(the tasks) to your resources?
cheers!
Hi Anoon,
it is not practical.
If the task requires a team of resources then you shall assign the same task to many resources, instead of creating resource crew and assigning it to many tasks where it is required.
The tasks are depended if there are technological restrictions on the order of work. Resource assignments do not change this. The links shall not be used only if the tasks are not dependent and can be done in any order. In this case the order shall be defined by the software if these tasks compete for the same limited resources. The computer shall select which tasks to do first basing on resource availability and schedule optimization criteria. Usually the best schedule is the shortest schedule.
Best Regards,
Vladimir
Hi Vladimir,
"Resources are assigned to tasks" - I supposed this is the conventional way.
Im thinking of the reverse - Tasks to be assigned to resources (using a resource pool, resources calendar and a defined series of activities). With this, I guess your tasks becomes independent with each other, meaning - no links (so Mikes "FS0" becomes irrelevant).
Can Spider do this thing?
cheers!
Hi Anoon,
your post is not clear to me.
Project resources can be defined before activity definition or later. It depends on the project nature. If you plan some project inside the organization you have Organization Resource Breakdown Structure ready.
Resources are assigned to tasks when both are defined. If you dont know specific resource that will do the work you can assign skill.
For an example: you need heavy bulldozer to do the work. In your resource pool you have Caterpillar and Komatsu. It does not matter which one to use though their costs and productivities are different.
So you create Skill Heavy Bulldozer, put both in this skill set, and assign Skill Heavy Bulldozer, because it is hard to say which one will be available at the moment when your task will be ready for execution.
Please clarify your question if I did not answer.
Best Regards,
Vladimir
Rafael,
With reference to your post # 60, again, Im not interested with your terms from outer space like "brute force"; "operations research"; "subroutines" etc.
I maybe interested in your "resource constraining" (Of course I dont understand it, but just let me try, please..?).
For example: Instead of defining first activities or tasks, you first define your resources (or you can figure out both at the same time?).
Now, once you had defined your resources, you can now assign tasks or activites to the resource or group of resources.
Just doing the reverse of what you usually do using available or current softwares.
cheers!
Vladimir,
I posted in Rapidshare the table you send me so others can look at it and make their own questions. I am aware it is not comprehensive but it is a start.
Spider Project Functional Features Table & other Software
For me only one sample job will do it, as we say here, “for a sample only one button is enough”. I will take a look at it and compare with Spider Project Demo.
Best regards,
Rafael
I can send you many examples of projects that you can level in different softwares and compare results.
You may notice that when you start the resource levelling the software suggests you to select the priorities. That is all - then activities that have your (defined by you!) priorities will get resources first. Thats all, the software does not even try to find an optimal solution.
In Russia this Spider advantage is just well known fact and nobody argues about this.
I spoke about this problem with Western PM software at IPMA Congress in Paris and PMI Conference in Boston in 1996. At these conferences I also spoke about Resource Critical Path (later called Critical Chain). Nothing was changed since then.
Best Regards,
Vladimir
Vladimir,
That MS Project does not look for an optimum solution is no surprise but that P3 neither is new to me, hard to believe.
UNBELIEVABLE ! ! ! !
Guess the only way to know is to compare side to side the same job under P3 and Spider Project.
Don’t take me wrong, it is just hard to believe. I would like to see some indepentent study on that.
Best regards,
Rafael
Hi Rafael,
the software that you use does not even try to find optimal resource constrained schedule. The best (like P3, P6. Open Plan) suggest the user to select some simple heuristics that will be used based on setting priorities to some activity fields.
Most primitive (like MS Project) use only one predefined simple heuristics.
So in the best case the user can try several simple heuristics trying to find the best one for the current project.
In Spider Project this approach is called standard.
But Spider Project includes iterative optimization algorithms that can significantly improve scheduling results. And this method in the software is called Optimization.
Though these algorithms do not guarantee that the schedule is optimal they will certainly produce near optimal solution.
That is why Spider Project resource constrained schedules in many cases are much shorter than the schedules produced by P6, MS Project and other tools though they are created for the same initial conditions.
Best Regards,
Vladimir
Anoon
All algorithms are systematic, this pompous name only means a set of instructions that systematically look for a solution, is the way a computer looks for a solution to any given problem, and once these general procedures are coded into a computer language are usually known as subroutines.
With regard to resource leveling, all software has its own algorithm, each looking for an optimal solution. Hopefully all will get close to the optimal solution, there might be different outcomes but close.
One way to get the optimal solution would be by generating all possible outcomes that satisfy the constraints and selecting the optimal one(s). Yes there might be more than one optimal solution. But these method, known as “Brute Force” would require an enormous amount of computer time, which is where these procedures excel.
The issue of resource leveling can be handled by almost any CPM software of today, what none can do, with the exception of Spider Project, is handling the resource leveling issue while at the same time considering other set of constraints, real constraints. This was the future, now it is the present, follow the leader.
If you are further interested into these types of issues you can look into the title of Operations Research, the branch of mathematics that deals with this kind of problems. After 30 years out of school to me this have become too complicated, just give me the tools.
About resource constraining without linking activities just imagine the following set of tasks you can work on only one at a time.
Do the laundry, Go to the Pharmacy, Go to Bank and make cash deposit.
All are completely independent activities so there would be no logic link, you most probably would solve the issue based on priorities, or maybe "float" the available time before they become critical.
Best regards,
Rafael
Hi Rafael,
I supposed that what you had stated in Post # 55 is too much for my very little understanding (if any).
Sytematic Algorithm...What is that???!!!
Resource constraining and without linking activites, so as to find the best possible solution using a machine???!
I STILL CANNOT BELIEVE IT!
cheers!
Hi Rafael,
in Spider Project you can select which cash flows to analyze. Your project may have many cost components (labour cost, material cost, machine cost, indirect cost, taxes, etc.) including payments, financing, income. For all cost components you define the cost of one unit. Some currency is selected as basic with unit cost equal to one, if some component is measured in different currency then the cost of one unit is defined by current exchange rate. Cost units for incomes are negative.
You can also create cost centers that consist of selected cost components.
So you can create cost center that includes your expenses on accrual basis and another cost center based on cash basis. As the result you will be able to analyze both cash flows. We also use this technique to analyze contract relationships - who owns to whom and how much at any moment.
Cash flow reports and S-curves can be published for any cost component and cost center.
And yes, Spider Project calculates NPV, IRR, MIRR and Payback Periods. Discount rates can be defined for all cost component separately (and may be different!).
Spider Project can show in parallel S-curves (cash flows) of any two project versions. One of these two may be baseline version or ALAP schedule version.
Spider Project keeps project archives, so you may be interested to compare current project version with the version created one week ago, one month ago, etc. including comparing cash flows.
Yes, we have such table. I will send it to you tomorrow.
Best Regards,
Vladimir
Vladimir,
I was checking on the modeling for an activity to start as soon as any of two finishes, you are right the logic was wrong, I have not found a solution within SureTrak limitations while on the spot I got it with functionality not available in SureTrak or P3 but could figure it out with the concept of consumable resources/material resources available in Spider Project.
In your SDPM presentation (see posting #31) on page 14 there is a Cash Flow Projection and I would like to know if you are using appropriate lags for your cash flow. I would never issue a cash flow curve on “accrual basis” but on “cash basis” that is, as it comes in and out of my bank account. This is a functionality I believe you are integrating with NPV or Net Present Value, this is also novel and not available in any other software I know. Please tell us if you have a whitepaper on this issue and how to get it.
I also would like to hear about S Curves in Spider Project, my software Primavera SureTrak is very limited and cannot generate reports in which you can compare the actual S Curve with a Baseline and cannot handle both Early and Late S Curves. Within SureTrak I can only generate a single resource graph at the end of my Gantt chart. Up to now the best functionality for Graphic Reports I have seen is by Primavera P3. What can you tell me about Spider Project?
Do you have a table comparing functionalities available between major CPM software that includes Spider Project?
Best regards,
Rafael
Hi Anoon,
yes, everything has limits. That is why we plan our resources, supplies, finances to be able to achieve our targets.
Hi Rafael,
very well said.
Best Regards,
Vladimir
Anoon,
Even if two activities use the same resource linking one to the other in order to avoid resource availability issues is not necessarily the best approach. What if the two activities are in no way dependent of each other, as the job progress the relative start of one with respect to the other might switch, by using activities link you will prevent the software to schedule the best option. For small jobs you can handle this manually but for jobs with thousands of activities you are better off with the assistance of your computer, use it to your advantage.
Resource constraining is not about finding a feasible solution is about finding the best or close to best solution. It is an optimization problem that requires the use of computer algorithms to systematically look for the best solution, a solution that might change as your schedule moves with time.
Best regards,
Rafael
Vladimir,
Again, it sounds like from the commercial side (Sorry).
I presumed you are saying that this will apply to a given or defined overall duration (say, contract duration)?
And I would say limited contract duration, with limited space (literal space) or defined interim milestones or whatever that has limits (and I guess everything has limits!).
cheers!
Hi Anoon,
I answered your question several times.
These two schedules are linked without constraints.
If an activity in construction schedule uses sone unique equipment then you may link delivery and usage activities with FS link.
If materials may be used on many activities then dont link activities but use material levelling and activities that require materials that are not available will be delayed automatically. Material levelling is present in Spider Project.
Cheers!
All,
Please allow me to go back to Vladimir’s statement:
"We start with the construction schedule as if materials are available at any moment. As the result we get material requirements at any moment."
If you’ll just admit (honestly), I believe everybody is doing the same thing, regardless of the software used.
Construction scheduling is not difficult if you got the details with you, which means complete engineering details. Consummables are easy to define and these shall fit with your activities.
Delivery schedule or Material availability is another story.
Linking the two (Construction Schedule and Material availability), is where the problems will come-up!
This is my question, is Spider capable of linking the schedules (as mentioned above) without using constraints (or without nailing certain activity or activities)??
This is what Vladimir didn’t answer!
cheers!
Anoon,
Because Primavera P3 and SureTrak cannot model consumable resources, then you means there is no way you can define materials into P3 and SureTrak? You can define them as non leveling resources, a limited functionality for cost and cahsh flow tracking, but this is essentially what you can do when you have, or are required to use outdated software.
You can define your materials as different type of resources and this make a huge difference, just that Primavera people have not realized this yet. You can define some of your material resources as consumables, this to model other scheduling constraints and not merely cost or chash flow.
I thought you are going to beat Vladimir? I will try, but my "hidden agenda" is to use Spider Project as the model of what our software shall be capable of doing. Believe me after a few years of scheduling you ask for more than simple FS0 relationships, this is primitive, the PDM functionalities are more flexible but still in the Dark Ages, on the other hand Multi Constraint Scheduling where all constraints are integratede and taken into account at the same time is the modern way, get into the new Millenium.
Best regards,
Rafael
Rafael,
I thought you are going to beat Vladimir?
Just assume that Im working on another planet where planning can be done in various ways.
Though I believe (still) that there is only one way of doing it. And of course with the intention of making as much profit as you can (this is what I meant by commercial).
"Material Resources" for me, is always consummable (you dont need to emphasize that!), but this has always limits as well (again, this is engineering), how can you make profits if your consummables has no limits?
sorry for interruption (you know Im working!) Ill be back later.
cheers!
Anoon
When you resource load your schedule you load it with different purposes and different types of resources depending on your modeling needs:
1) Some resources are set as non-leveling resources but are required for cost loading and to predict the resource demand.
2) Others you set them as leveling resources that are used as available and then after being used by the activity(ies) are released to be available to be used again.
3) Consumable resources are a special kind of resources that when used are consumed at the specified rate, these you can also replenish at another specified rate such as a one day delivery.
Although I do not have spider Project I believe Spider Project uses the term Material Resources to mean Consumable Resources, a matter of semantics. This at times might be confusing for the few used to use a different name for this purposes and even more confusing for the many whose software do not provides this functionality of Consumable Resources. The software I use/used, Primavera P3 (not any longer) and Primavera SureTrak lack this functionality.
Best regards,
Rafael
Hi Anoon,
I don’t understand what do you mean by technical side and commersial side.
I described the way people work here.
I am sure that in serious projects like Nuclear Power Plants construction, shipbuilding, aerospace, etc. it is not possible to work other way anywhere.
What is a challenge to Spider?
Best Regards,
Vladimir
Vladimir,
If you were a judge, I would say, your Honor I would like to hear (if I may) an answer that comes from the technical side of your personality (and not from the commercial side).
Your first sentence: "we start with the construction schedule as if materials are available at any moment. As the result we get material requirements at any moment." This, for me is valid.
The rest are rubbish!
Remember, this is a challenge to Spider!
cheers!
Hi Anoon,
we start with the construction schedule as if materials are available at any moment. As the result we get material requirements at any moment.
Material requirements reports are sent to supply people.
They create supply schedule for the main equipment that shall be ordered in advance and this schedule is included in the construction schedule.
There is only one project schedule that includes construction, delivery and financing schedules.
You can use constraints like milestones that represent deliveries with the links to those activities that use these products, but better to monitor the supply process as the part of the project monitoring.
Cheers!
Hi Pinan,
yes, material supply shall be planned according to material usage. If some equipment shall be ordered, made and delivered for you then your schedule shall take the duration of this supply into consideration.
If materials are available at any moment then supply schedule and material levelling is not necessary - you just order materials when needed and will have them at any time. We use material levelling only for those materials that are not readily available.
Material levelling is also used for simulation of moulds flow. Moulds are installed (consumed) and then delivered after concreting. And the total quantity of moulds (frames?) is restricted.
Best Regards,
Vladimir
"So construction schedule defines requirements to supply. Delivery schedule defines restrictions to construction."
Vlad, I like that statement. If you dont mind to answer, I may ask if in your personal style of scheduling:
1. What do you do first, Construction Schedule or Delivery Schedule? (considering that all elements that you might need are known).
2. If delivery schedule is not known, how are you going to simulate construction schedule? Do you use constraints?
3. Which comes first, "chicken or egg"?
cheers!
Anoon,
if some materials are not available construction activities that use these materials are delayed until material delivery.
Material requirements at any moment are defined by construction schedule. If your supply schedule cannot satisfy these requirements then activities in construction schedule are delayed.
So construction schedule defines requirements to supply. Delivery schedule defines restrictions to construction.
Cheers!
in our project, we level material according to usage
"In this case you define delivery schedule and construction schedule will be adjusted to material availability."
Vlad, I dont understand this statement.
Material availability is your delivery schedule, right?
construction schedule is construction schedule!
Here, what is driving what? Are you going to constrain any of them?
cheers!
Hi Pinan,
yes, material levelling may be applicable for the project having small storage area. In this case you shall plan material delivery to your storage in accordance with project material requirements and storage space that shall be also considered as one of project materials.
Best Regards,
Vladimir
Materials are equivalent for consumable resources. So equipment that you plan to install is also some kind of material.
You can define necessary materials as fixed quantities or the quantities required per unit of activity volume. If the volume of work will change then the required quantities of materials will change also.
Material levelling is necessary when you have supply (delivery) restrictions like in your example. In this case you define delivery schedule and construction schedule will be adjusted to material availability.
Cheers!
MATERIAL level maybe applicable for the project having small storage area?
I supposed "materials" is a known element of the project (whats the use of engineering anyway?).
Maybe tools or equipment to install these materials are not known or may vary, but I cannot imagine why you need to level materials to fit in time...?
When your activities have fixed units of materials, how are you going to make it flexible?
No problem if this is the trade secret. But I dont know the features of your software, so may suppose that your software level materials, why not?
Best Regards,
Vladimir
Vladimir and All,
For your information, Im also employed, so its a trade secret which I cannot tell you! Sorry...
cheers!
Yes, Spider Project does it. I dont know what software do you use.
If you dont agree with answers 1) and 2) then what is your answer?
Cheers!
Vlad,
The first items (1;2;3), yes thats right.
My question is not how to link, but what would be the best relationship to define or simulate material delivery in your schedule?
I dont agree with the answers by the way (I just presumed youre joking, were not leveling materials of course! or are you doing it?).
cheers!
Hi Anoon,
let me determine your task as follows:
1) there is some activity that require certain materials,
2) you don’t have these materials at the moment, so material delivery shall be simulated in your schedule as an activity or a set of activities,
3) how to link these activities?
Confirm if I understood your question properly.
Answers:
1) If this is one time delivery then connect delivery activity with your activity with FS link,
2) If delivery has duration (materials are delivered in parallel with your work) then link delivery with your activity with both SS and FF links,
3) If your software can level materials then don’t link them at all. Activity will not start until materials will not appear in your schedule.
The last is preferable if you don’t know which activity will use delivered materials first.
Best Regards,
Vladimir
Rafael,
we apply risk simulation to get target dates and costs that can be achieved with reasonable probabilities.
And we suggest to use deterministic (preferably optimistic) schedule for setting tasks for project workforce or subcontractors but to analyze buffer consumptions for project performance measurement.
It is a theory that we call Success Driven Project Management. You can read about it here: http://www.spiderproject.ru/library/SDPM_Canberra2004.pdf
I have serious doubts about Monte Carlo application to the real life risk simulation. It is very time consuming if try to achieve necessary precision. We suggested and use more simple approach that is sufficient for our needs. You can use it with Suretrak though with more efforts than in Spider. If you will remain interested after reading the presentation we can discus it.
The schedules in Monte Carlo simulation shall be calculated using the same algorithms as in your software. Without resource limitations it is not critical if all softwares use similar CPM calculations, but resource levelling is different in any software. If Pertmaster uses its own levelling algorithms then it produces probability distributions if to manage project different way.
It can be easily noticed by changing priorities for resource levelling in your software - the results will change. Even with the same priorities different software uses different algorithms. So to produce reliable results Pertmaster shall use Primavera engine for Monte Carlo calculations. And this results shall be different for MS Project users and Primavera users for the same project.
So I agree with you that internal risk simulation is preferable.
Best Regards,
Vladimir
Im still wondering why you gentlemen (and ladies?) are trying to argue about the importance of Start-to-Finish (SF) relationship.
Let me try for example:
1. an equipment with a concrete foundation;
2. Considering that you can construct the concrete foundation without any hassles but only the anchorage that you will need to tie with the reinforcements of your concrete foundation (so that you cannot place concrete without it).
3. You still have no idea when this equipment (including anchorage and appurtenances) will be delivered to you.
4. How are you going to schedule this? What relationship will best define the delivery of anchorage and the installation of the rebars?
cheers!
Vladimir
My software does not provide for the automatic functionality on the use of buffers nor do have integrated Monte Carlo Simulation, so my knowledge is somewhat limited.
You have mentioned before that you use the probabilistic functionality within Spider Project to determine adequate level of buffers. For this I have some idea on how to implement it but I believe that the deterministic critical path does not necessarily is the same as the most probable critical path under a Monte Carlo Simulation. Please comment on this and other practical uses of these functionalities.
Also I don’t believe that exporting a P3 schedule to Pertmaster will be the same as if running Monte Carlo from within your software, they are not 100% equivalent so each of the many hundreds Monte Carlo runs will not be 100% equivalent, some functionalities will be lost other will not be equal. I would prefer to run Monte Carlo from within my software. Do you agree or disagree on this statement?
Best regards,
Rafael
Hi Mike,
in most cases I agree with you, I also prefer detailed schedules where most relationships are FS without lags. But in some cases and in some projects like linear projects it is not practical. And in some projects we meet complex relationships like one we discussed with Rafael that cannot be simulated with simple basic logic.
I dont agree that resource hours give sufficient information for project levelling. Some resources like cranes are used on many activities part time and very often the cranes are critical resources in construction projects.
Limited space often restricts the works that can be done independently. It does not mean that the next crew will do the following work.
I also dont believe in manual levelling. The projects are rarely performed as planned. And there is a need to reschedule the project almost each time when actual data are entered. It is too hard to do manually if resources are restricted. And impossible for large projects even if you use only one resource for all activities.
Best Regards,
Vladimir
Hi Vladimir
In my simplistic world you cant paint a wall until it is plastered. Neither can you plaster a wall unit it is built.
No matter how complex the project one task follows the other within a defined space.
My definition of a defined space is where one trade can work on its own - until the next trade moves in.
It is so simple that it doesnt need any further explanation.
All of this is encapsulated in my bottom up FS method.
I can see no better way of construction planning.
Best regards
Mike Testro.
Hi Mike,
space is also a kind of resource.
Why do you loose an interest to the topic?
I think that it is interesting to discuss how to simulate complex cases of project modelling.
And please suggest how to simulate that some activity can start after finish of any of several preceding activities using simple bottom up basic task method.
Best Regards,
Vladimir
Hi Rafael,
Not all.
Logical Relationships, Start No Earlier Than, Finish No Later Than are shown at the bar chart, other constraints (supply, financial, resources) that delayed activities are listed only in the schedule report.
You are right - it is not necessary to be mathematician ro create project models. It is enough to use logic and common sense.
When we prepare project planners for construction projects we prefer construction engineers to IT people. It is necessary to understand the logic of works, to learn Spider is much easier.
Best Regards,
Vladimir
Hi Vladimir.
Is it only resource linking?
What about work space?
All of this can be done with a simple bottom up basic task method.
I am beginnining to think that we are both talking about the same procedure but approaching from diverse directions.
In any case I am rapidly losing interest in the whole topic.
Dont worry I wont lock the topic.
Best regards
Mike Testro.