Let’s Challenge SPIDER

Hi Vladimir

Most software has a cost v income function but will not stop the programme if the preset parameters are exceeded.

That is left to the judgement of the manager assisted by his planner’s reports.

I do not like the idea of computers making decisions for us.

Best regards

Mike Testro

Vladimir,

“If financing schedule is a part of your project schedule model then Spider Project will calculate project schedule taking into account financial limitations and delaying activities when there are no money to proceed.”

You are thinking out of the box. With my mindset of a general contractor, not of a developer I was wondering on the application of this functionality. Yes I accept financial constaints as real constraints, and find your approach very clever.

Let’s move to the issues on “materials” constraints. You mentioned earlier in another thread about the use of material resources as to constraint your schedule under limited available work space. But can this also be used as a way to model limited storage space at the jobsite? Let say a job in the middle of downtown or an offshore rig.

And what about limits on hoisting facilities? This is a queuing or “waiting line” problem., I have no idea on how to model that into a CPM schedule but into a GPSS (Gen. Purpose Symulation System) or the like.

Best regards,
Rafael

Hi Mike,
it is not necessary to level costs if you just want to know project cash flow. If you can work without financing then it is OK and you will know how much money you will spend until next payment.
But if your money are limited then you will depend on project income and it is nice to know project schedule that is adjusted to your financial capabilities.
When Russian Ministry of Defence planned large 10 years program they found that program cost was very uneven - expenses for one year were several times more than for another year, etc. So the program schedule was unrealistic because it will not financed this way. So they input expected limits of program financing per year and got new schedule that was approved.
Mike, computers shall help us to decide. Play what if - computers calculate faster and can try much more different options than people.

Hi Rafael,
Storage capacity can be simulated the same way. Actually we have successful experience of Just in time construction management in the middle of downtown. Project lasted one year and a half and was finished two days later than was planned in the initial schedule.
Do you mean cranes by hoisting facilities? My English is not very good, so sometimes I will ask for the explanations.
The crane is one of the project resources. And usually it is critical resource especially in the construction in the middle of downtown. We simulate its work as follows:
1) Estimate the average number of lifts in one shift,
2) Estimate the number of lifts necessary for different works (activities) during one shift,
3) Divide this number by total number and multiply by 100.
Now you know the workload of the crane on your activity.
Of course there are other activities where crane is 100% assigned because it does not lift but holds something and will not do other works in parallel.
I know queueing theory and applied it to some tasks in the past, but for project scheduling it is not necessary. I know only one practical task where it shall be applied: determination of the optimal number of trucks that shall serve the excavators in earth moving works. But it shall be done before scheduling.
Next week I will return from Germany and will answer faster.
Best Regards,
Vladimir

Vladimir,

Thanks for your response about how to model crane use; you got it right this was my question.

I am not familiar with the use of consumable resources as Primavera SureTrak or P3 do not provide for these. I believe that Micro Planner had the concept of consumable resources; to me it seems similar to your material resource, just another name, please confirm.

I got the following functionalities missing from our software would like you to tell me if they or equivalent are available in Spider Project.

1)Automatic Audit Trail of Changes: http://www.ronwinterconsulting.com/Making_CPM_Transparent.pdf

2)Longest Path Value:
http://www.ronwinterconsulting.com/Longest_Path_Value.pdf

3)Expected Finish Constraint: this constraint calculates Remaining duration automatically between updates as the difference between the Expected Finish Constraint and the Data Date. Not a must have but handy.

Best regards,
Rafael

Rafael,
I have read about the Longest Path and did ot understand its value. If activity is restricted by No Enarlier Than constraint what driving relationships will give us? Why it is necessary to know longest path if you know activities with the minimal float.
If it is necessary to know the path from the beginning determine the activity that has no predecessors with the minimal float and filter the schedule showing only those activities that have floats equal or less. Or just define that activities with the float equal or less than ... are critical and you will see the longest path in red.
If you see the difference then explain it to me.
Vladimir

Rafael,

Automatic Audit Trail of Changes in Spider Project is called Protocol of Actions. You can undo any specific action. I don’t remember when this feature was added to Spider Project but many years ago. The user can define how many actions shall be stored (the depth of undo’s). There are no limitations. You can try this feature in Spider Demo.

Expected finish Constraint will be shown if to compare forward and backward schedules. You can do it at any moment if necessary.

Best Regards,
Vladimir

Vladimir

Undo is not the same as audit trial, undo are done in backwards sequential order, with audit trial you can see your data entry history and make changes in non sequential order, if you can see what your last 40 or 60 changes were and undo only those you select then it will be a great improvement of what our undo in Primavera Products does, I also understand Primavera undo does not works with resource leveling. If Spider Project can undo specific actions in any order then this is great, please confirm it is not sequential that it can be discretionary in any order you wish.

About Longest Path you for whatever reason might be, you might need to compress or crash the path up to a specific activity, because predecessors can also be tied to other chains, float alone do not identify the driving activities of the particular chain you are investigating. The longest path to the particular activity is not necessarily determined by those predecessors with the lowest amount of float, even when the activity is artificially constrained.

http://scheduleanalyzer.com/sa_long.htm

http://scheduleanalyzer.com/sa_long_theory.htm

“LONGEST PATH Software extends the theory of Longest Path to every activity in the schedule. Just as with Total Float, every activity in the schedule can be rated by its Longest Path Value. “ Please note Longest Path is not available in any software, Ron Winter provide this without infringing Primavera Copyright in their products, he is enhancing them is a good deal for both. I believe he only works directly with the Database, and then after the changes are done in the database you can see them in P3 until it runs any procedure that recalculates these values.

I don’t have Longest Path Software, I don’t know if it would work with SureTrak P3 files but I believe it can because here the Longest Path Software is dealing directly with the database values.

If someone can develop by their own this functionality is Spider Project, stand to the challenge and extend it to include Resource Critical Path and float plus all other simultaneous constraint sets. That I want to see, Financial Critical Path, I want all these functionality and still able to see driving constraints; predecessors/succesors logic, resources, financial, all.

Best regards,
Rafael

All,

I supposed Mike did a bias act on the other thread (for he is a Moderator), he just locked it when he feels that he’s about to lose. Now he wants private message, that’s unfair Mike.

Here, who can challenge Spider? I don’t know anything about Spider!

I believe Spider is not the issue! It is longest path; critical path; resource criticality; resource leveling; CPM...etc.

Rafael, I’m on your side now, if you want to ban CPM, I can make you a good coffee!

cheers!

Hi Anoon

Whats the point of having a bit of power if you can’t abuse it now and then?

Best regards

Mike Testro

Hi Rafael,
I confirm that in Spider Project you can undo any specific action that was done earlier (like 15 actions ago) without undoing next actions.

Maybe I do not understand what is longest path. I just don’t understand the reason to compress the preceding activities if current activity has No Earlier Than constraint. I understand the usefulness of DRAG and we included this in Spider Project. DRAG shows what time each activity adds to the project duration. It can be calculated if to make activity duration equal to zero. Activity may have 10 days duration and being critical but with only 2 days DRAG because there is other subcritical path only 2 days shorter.

Spider Project can show all activities that precede current activity, it also shows driving relationships, it shows floats. You can filter the schedule by float value. You can consider the set of activities that precede current activity as the separate project with its own critical path, DRAG values, etc. It is sufficient for schedule analysis and knowing predecessors to activity with NET constraint does not help at all.
Please explain what I miss.

By the way Spider Project calculates not only activity floats but also assignment floats that may be different.

Best Regards,
Vladimir

Hi Anoon,
you need not to know Spider Project. It is about potential requirements to any PM software.
Like I need to simulate this situation or to do this analysis. Is it possible?
Spider Project is just an example. I hope that somebody will suggest something really useful for all and we will discuss how it may be achieved.

There is forum for Spider Project users in Russian where people ask questions like "I want to simulate that next activity can start if any one of two preceding activities is finished. How to do this?"
Unfortunately there are few similar discussions here. I hope that this one can provoke to set really hard but still useful tasks.

Best Regards,
Vladimir

"You can consider the set of activities that precede current activity as the separate project with its own critical path, DRAG values, etc."

Seems like the equivalent of Longest Path, this is useful and relevant functionality.

"I want to simulate that next activity can start if any one of two preceding activities is finished. How to do this?"

Vladimir please follow the link and download the video showing this being done under SureTrak, any software can do that. This is using SF relationships and an as late as possible constraint, I suppose under "FS0 relationships only" Mike cannot simulate this.

http://rapidshare.com/files/288615256/FIFO.avi

Best regards,
Rafael

Hi. Has Spider project that useful for everything "jump to predecessor/succesor" button P3 has? In 2 clics, it takes you to the predecessors of an activity. It is very useful, I don’t know why it is not a feature of modern software, they seem to be focusing in making things more and more complicated instead of making common tasks more easygoing.

This is what I mean, I can get the driving sequence of an activity just by following its driving predecessors:
http://screenr.com/ZhH

Can Spider import/export to MS project or Primavera format? Power Project can, it is very useful since these two are many industries’ standard.

Hi Rafael,
I mentioned this task just as an example of questions that are asked in our forum. I am glad that Suretrak can do it though I did not understand about SF relationship with ALAP constraint.

Hi Carlos,
Spider Project has "jump to predecessor/succesor" function and can export/import to MS Project and P6. It has no direct export to P3 but exports to mpx that P3 understands.
Besides it exports/imports to text and databases. Any Spider table can be exported to Excel and vice versa.
Spider shows links of current activity in the diagram. Clicking on the preceding or succeding activity you will see its properties including links, Then you can click on another preceding or succeding activity and again see its properties (duration, volume, assignments, links, etc.).

Best Regards,
Vladimir

Vladimir,

Ironically activity CCC is set to be the predecessor, the links are the following

CCC --> SF0 --> AAA
CCC --> SF0 --> BBB
CCC has a “As late as possible” Float Constraint

I uploaded the P3 file under the following link so anyone can download it and explore it, because I am using SureTrak you will have to adjust your Layout.

http://rapidshare.com/files/288646383/FIFO.zip

I am still wondering how to schedule for the activity to start as soon as any three out of a set of 10 finishes. Real life is not as easy as FS0 only.

Best regards,
Rafael

Rafael,
what if your activities are in the middle of some schedule?
Then ALAP will not work.
Besides, SF means that AAA and BBB will finish after CCC starts. It means that CCC can start early - it may happen as the result of resource levelling.
Please clarify.
Best Regards,
Vladimir

Vladimir,

It will take me some time to analyze your question, although it still continue to move the activities there is a possibility of other issues not being considered, I am also finding issues on the calculated total float for the driver of CCC, this is another issue. If latter you can e-mail me a P3 file then it will be easier for me to model what you are observing.

I was also thinking in the possibility of using consumable resources. Using negative consumption the predecessors can replenish the resource from 0, the successor activity will not be able to start until you have the required resources, but I do not have this functionality as to explore it. I was also thinking about the activity consuming the resource but at the same time replenishing it at the same rate as to prevent the resource from being consumed and still being able to be replenished by other activities and used for constraining the start of other activites.

Do you have another idea?

Best regards,
Rafael

We use resource production and consumption.
Activities are not linked at all. But previous activities produce some dummy resource and succeeding activity use this resource. The resource may be consumable or renewable - both options can be applied. Resource produced by one activity is sufficient for performing next activity.
It can be easily done for three activities out of ten.

Best Regards,
Vladimir

Hi Vladimir

This thread is moving on very well. You said recently:

Activities are not linked at all.

Not At All! not even FF SS FS or SF. No lead lags?

Welcome to the world of Space - Time continuom universe of star trek planning.

Spider contols the WEB.

Best regards

Mike Testro.

Hi Mike,
activities are linked through resources they use.
I hope that you will accept this clarification.
FS, SS, FF, SF are not enough.
Best Regards,
Vlafimir

Vladimir,

You mean I figured it out without my software having the functionality and even without being a full time scheduler? So the average part time scheduler can figure it out?

That would prove one of my points, give me the functionality let the software do the math.

Do you have a constraints screen wher you can identify driving constraints in the way you can see driving predecessors? Can you print in the bar chart driving constrints, let say at the left of the bar while at the right you have the activity description?

Mike,

The constraints are real, not always a FS0 relationship can define what is driving your activity.

Best regards,
Rafael

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.

Don’t worry I won’t lock the topic.

Best regards

Mike Testro.

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 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 Vladimir

In my simplistic world you can’t 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 doesn’t 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,

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 don’t 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 don’t 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

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

I’m 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!

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

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

Vlad,

The first items (1;2;3), yes that’s 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 don’t agree with the answers by the way (I just presumed you’re joking, we’re not leveling materials of course! or are you doing it?).

cheers!

Yes, Spider Project does it. I don’t know what software do you use.

If you don’t agree with answers 1) and 2) then what is your answer?

Cheers!

Vladimir and All,

For your information, I’m also employed, so it’s a trade secret which I cannot tell you! Sorry...

cheers!

No problem if this is the trade secret. But I don’t know the features of your software, so may suppose that your software level materials, why not?
Best Regards,
Vladimir

I supposed "materials" is a known element of the project (what’s 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?

MATERIAL level maybe applicable for the project having small storage area?

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!

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

"In this case you define delivery schedule and construction schedule will be adjusted to material availability."

Vlad, I don’t 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!

in our project, we level material according to usage

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!

"So construction schedule defines requirements to supply. Delivery schedule defines restrictions to construction."

Vlad, I like that statement. If you don’t 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!

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

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!

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,
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

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

Rafael,

I thought you are going to beat Vladimir?

Just assume that I’m 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 don’t 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 I’m working!) I’ll be back later.

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