(1) Explain your problem, don't simply post "This isn't working". What were you doing when you faced the problem? What have you tried to resolve - did you look for a solution using "Search" ? Has it happened just once or several times?
(2) It's also good to get feedback when a solution is found, return to the original post to explain how it was resolved so that more people can also use the results.
Resource Overloads Bar and Resource Overloads Reports:
The value of overloads reports shall not be underestimated. These reports are more reliable than overload bars/diagrams. A short duration overload of any resource makes the schedule not feasible, this you will not miss under overload reports but easy to be missed if looking at the overloads bar. When checking unleveled schedules or leveled schedules from external software this functionality can be invaluable.
Resource Dependencies:
In summary: I would like the following:
For Resource Overloads:
For Resource Dependencies:
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Anoon,
I make conclusions about your schedules basing on your posts. And these conclusions are not on the quality of your schedules but on the projects you deal with.
The schedulers do what they are told to do (if they agree with this). So the problem is in the poor understanding of the value of proper scheduling by most top managers. In the companies where top managers understand that proper scheduling can save time and money the scheduling itself is the team work and planner/scheduler participates in decision making becoming very important member of the management team.
Anoon,
I make conclusions about your schedules basing on your posts. And these conclusions are not on the quality of your schedules but on the projects you deal with.
The schedulers do what they are told to do (if they agree with this). So the problem is in the poor understanding of the value of proper scheduling by most top managers. In the companies where top managers understand that proper scheduling can save time and money the scheduling itself is the team work and planner/scheduler participates in decision making becoming very important member of the management team.
Anoon,
I did not talk about best practices.
We have different experience. Your schedules never include parallel activities competing for the same scarce resources, my schedules always meet this. That's all.
As I always wrote good schedule model shall include everything that shall be done (quality assurance activities, commissioning activities, as anything else) and risk events that may happen or not.
Anoon,
of course the schedule shall consider everything that is required for sucessful project delivery.
It does not mean that there is only one way of activity sequencing with FS links only.
OK Anoon, I just see that you don't want to answer to my question.
It looks like you never met the situation when the work can be done different ways. I've met with this a lot of times. And I agree that when the work can be done in only one straightforward sequence the scheduling and leveling (and any scheduling software) are not needed and out of sequence may never happen.
Anoon,
in my example activities 1, 2 and 3,4 do not depend on each other. FS are linkes between activities 1 and 2, and between 3 and 4.
And creating artificial links lead to poor schedules like the order that you suggested. Doing all activities one after another though they may be done in parallel is poor solution.
I think that my question was clear and that you can suggest the best schedule of this 4 activities project.
My question was if your decision on the order of activity execution in your schedule was based on activity floats.
Good project model includes only those activities, dependencies, resources, etc. that are real. The software is used for finding the best way (best order) of activity execution. If the model is good and includes all constraints that people consider when schedule their projects manually the software provides feasible results.
Adding any artificial constraints and dependencies restrict software options for finding the best solution and lead to worse schedules. But sometimes preferential logic may be added (to build the road from point A to point B or vice cersa?) and in this case different options shall be tried for finding the best solutin.
So the model where the order of work was already selected by people is not a model at all. It is the result of manual leveling that is poor in most cases.
In the second link there is a column called Preceding Activities, you will see that all links are FS.
Vladimir, Anoon,
If I may, here is a basic model I made for a more complex project, with the help of Vladimir. The main purpose of the basic model was to find a way to solve the following problems:
1. Project must finish in a maximum of 270 day;
2. Each street must finish within 60 days;
3. No overallocations.
All links are FS.
The following capture shows the activities of 1 street:
https://i.postimg.cc/MZnnSBnT/Street-Activities.png
The next capture show that for 1 street there are no overallocations:
https://i.postimg.cc/CMRg1HC3/One-Street.png
Next is the project scheduled with CPM and has a lot of overallocations:
https://i.postimg.cc/rmdP8g6g/No-Leveling.png
Next is the solution provided using only the well constructed model and resource leveling:
https://i.postimg.cc/05wBFt0y/Leveled.png
Now Anoon, the sample consists of 9 streets with no overallocations/street, but the real project has 30 streets with overallocations, how many iterations do you believe a scheduler would have to make until a right solution would be found? How many if each street would have overallocations?
Using a good project model and a configurable resource leveling algorithm it would take you minutes instead of hours or days.
Best regards,
Bogdan
OK, Anoon,
just imagine that resource A in my example is fitter and resource B is welder.
Activities 1 and 3 require fitter and activities 2 and 4 need welder.
In CPM schedule activities 1 and 3 start simultaneously that is not possible since you have only one fitter (or fitting crew) and only one welder (or welding crew). So it is necessary to decide if to start with activity 1 or activity 3.
I asked about your decision and if it is based on activity floats.
You suggest to rely on scheduler intuition and manual leveling. I don't think that the scheduler can manually level large schedule and get the best possible solution and then repeat this process when any information was changed (activity delay, changes in resource availability, changes in productivity estimates, etc.). Manual leveling is hard and time consuming job. Our schedules consist of many thousands activities and manual leveling is not an option.
Anoon,
let's look at the sample project below
Resource A is overloaded and so it is necessary to decide what activity to do and what to delay?
All dependencies are FS.
What is your decision and is it based on activity float?
Anoon,
as I wrote earlier activity floats is only one of many factors that are considered in resource constrained scheduling.
The aim - to create the schedule that has minimum overall duration taking into account all existing constraints. The software will not prefer one schedule to another if these schedules have the same duration.
I never suggested to use retained logic only because people may miss something when schedule model was created or something may change. Out of sequence may happen if the schedule model is not perfect and shall be adjusted.
Resource overloads happen when the schedule was not properly leveled.
Anoon,
if the order of work does not matter (project duration is the same) the software may select any order.
If there are some preferences then enter activity priorities and the software will select the preferable order.
Anoon,
when several activities require the same resource at the same time it is necessary to decide what activities to delay. Wrong decision may lead to the schedules that are longer than necessary. That is why the software looks for the decisions that minimize overall project duration. Some algorithms are based on activity floats but it is not sufficient for finding the best solution. Spider Project uses sophisticated optimization algorithms that usually create shorter schedules than created for the same projects by other software. Look at this discussion http://www.planningplanet.com/forums/planning-scheduling-programming-discussion/574396/comparison-resource-levelling-algorithms-di
So right decisions shall be based on the consequences to overall project duration and even if you assign scarce resources to activities with largest float it does not guarantee the best schedule. It is necessary to look much further than to activities competing for the same resources at current moment. That is why we need computers - to help us to take right decisions and not only to print nice reports.
Anoon,
it is obvious that it is not possible to show real life schedules in the forum discussions. So discussing scheduling problems people use examples.
Now imagine that you got following real life task:
Determine what numbers of people (of different specialities), machines and equipment you will need at the remote sites and what spreads to create for building 730 km pipeline to certain date and with other time constraints like the need to build certin parts of it at predefined small time windows?
Using more resources than necessary means additional expenses, using less resources than necessary means finish delay and potential penalties. Missing time windows mean 6 months delays.
We did this creating project model consisting of 9000 activities and optimized resource requirements using resource leveling and risk simulation. Can you suggest any other way? I don't think that superintendents look for many months ahead deciding who shall do what and in what order.
As you certainly know resources are always restricted. And the software can estimate much more options for finding the best way to do the job. But it may be useful only if it takes into account all existing constraints like do the people that make decisions. Superintendents will rely on the schedules created by the software if it takes into account everything they do.
We met disbelief on construction sites many times but later, after system implementation, the same people told us that now they don't understand how did they work earlier.
Anoon,
ALAP (zero free float) is used when you need something to be done "Just in time".
Example: it does not make sense to deliver materials long before they are required.
Negative float is an information that helps to analyze project status but is useless for project network analysis. Even if my project is late I still need to know schedule critical path and activity floats in the current schedule calculated creating forward and backward paths from achievable dates. By Critical Path I mean Resource Critical Path, traditional Critical Path is its particular case if project resources are not limited.
Anoon,
looking at the Gantt Chart you may notice that some activities do not start at the early start day and may be interested why. One of the potential reason - an activity start was set as ALAP, other reasons may include the lack of required resources, materials, costs. This is what we call Delay. It does not consider due dates and so negative float does not matter.
Anoon,
if an activity does not start at its early start time then it is delayed for some reason. Activity delay does not necessarily means project delay. And negative float also does not mean that an activity was delayed. Maybe target date was too close or some of the previous activities took longer than expected.
I don't like and approve negative floats. Floats are used for schedule analysis and if an activity is critical in the current schedule it has zero float even if the project is late or some time constraints were not met. Spider Project calculates (but not uses) negative floats also (as a separate field) but just for the reference and for people who are used to this.
Activity resource constrained floats and resource assignment floats are not the same. Look at slides 56 and 57 of my presentation at recent Construction CPM Conference:
http://www.spiderproject.com/images/img/pdf/Construction%20CPM%20Confere...
Vladimir,
Today software update shows improvements on Reason of delay, it looks like some work is in progress, I like the improvements so far, looking good, very good.
Best regards,
Rafael
Anoon,
I don't understand what are you trying to prove.
Of course there are uncertainties and of course they shall be taken into account when contingency reserves are calculated.
Nobody here suggest to use "Retained Logic Only".
But life is more complex than you proposed, FS only does not work in most projects and particular in the pipeline construction projects that you used as an example.
Then what is the reason for delay for Activity 2 in following scenario?
Same as if not for ALAP?
Marcus - "we could say that the ALAP modeling condition would also be a planning attribute, not a top reason of a delay"
This might answer a question I had on my mind about showing delay reason if not for ALAP. Your reasoning about it being an attribute at first sight looks good.
I recall an old article on 3 scheduling gurus complaining about how difficult it is to understand what is driving schedule logic, this "Reason of delay" field can help a lot.
Rafael,
Considering what you said, I must agree with you, "calendars" are natural object atributes, and shuold not be considered a delay generator during the natural scheduling process, in the same way we could say that the ALAP modeling condition would also be a planning attribute, not a top reason of a delay.
Anyway, the "report of the reason of delays", is really very useful for planners.
What can be a “Reason of delay”?
Am I right when a say that all the considered "delay reasons" could be detached as, any re-scheduling caused by : actual execution performance, external risk factors not mapped, and project's constraint limits?
These ones bellow should be considered a composition of the others above.
Anoon,
adjustments do not always mean violation of approved logic.
You described uncertainty that shall be considered in risk analysis.
Marcus,
Calendars will always be considered in the calculations of "links" early dates but ultimately the delay is on the driving link. It is the driving "link" [logic-link/resource-link/date-constraint ...] what gives meaning to reason of delay. If you tell me the delay reason is some calendar and nothing more I will be lost, but if you give me the driving "link", whatever it is, I will get it, "link" calendar will be known as well as activity and resource assignment calendars. Calendars can be omitted as a reason of delay without loss of meaning.
Maybe the statement - "Data Date, activities not started with no active driving links, no active driving resources and no active driving Date Constraints will be placed at data date" should be changed to - "Data Date, activities not started with no active driving links, no active driving resources and no active driving Date Constraints will be placed ASAP after data date."
Maybe ALAP should also be considered a possible "Reason of delay".
Figuring out "Reason of delay" is not easy, this field has huge potential to be of high value.
Hi Rafael,
could we include, "not 24hd7dw Calendars"?
What can be a “Reason of delay”?
All activities are placed somewhere in the schedule, if the “Reason of delay” is empty, something is missing.
What can be a “Reason of delay”?
Am I missing something?
In the following scenario "Reason of delay" misses to mention there are two driving links, this is misleading. Better say reason of delay is a predecessor link, then by looking at other reports the scheduler should be able to identify all activity links that caused the delay.
Date constraints should also be included as these can delay an activity.
we have not these problems here.
If the change of construction sequence is reasonable and does not endanger reaching contractual milestones successfully Owners do not object. But contractors are responsible for meeting major milestone dates and so they shall not agree with dates that are not achievable.
Yes - There is resource link from activity 1 to activity 4.
But Reason of delay column for Activity 4 is empty. I expect it to show Resource A 7 days without specifiyng if because of Activity 1 or 2, both caused the overload prior to leveling. In other words same reason as that shown for Activity 3.
I don't understand why did you write that no reason for activity 4 delay is shown.
There is resource link from activity 1 to activity 4. I understand that it is not sufficient for starting both activities 3 and 4 in parallel.
Vladimir,
dates do not show why an activity is delayed
Of course not, same as delay duration does not tell why an activity is delayed. Duration is based on some calendar while a date of delay start can be as useful. I can live with only the delay duration. I am happy with how delay reason is supposed to work but there are some misses, to my surprise some delayed activities show no delay reason this should be esy to fix but I would like to see when delay reason was due to materials of financial constraints.
For the purpose of creating the snapshot schedule better keep the compromise, just keep reminding users that there is a pragmatic compromise.
Best Regards,
Rafael
Rafael,
dates do not show why an activity is delayed.
Creating multiple resource dependencies creates an impression that all preceeding activities shall be finished for current activity to start. Yes, this is the compromise but useful.
Resource dependencies are always ambiguous.
Before leveling: Please note there are no links among activities.
After leveling:
To created resource dependencies adds ambiguity and can be misleading. It was the use of resource by Activities 1 and 2 that delayed Activities 4 and 4.
To say the delay reason for Activity 3 and Activity 4 is availability of resource A by sept 9 is not ambiguous. Unfortunately some are missing, activity 4 was delayed and no delay reason is shown.
I understand the main purpose of creating resource dependencies is to be able to create a snapshot of the leveled schedule that does not depends on resource leveling, that uses not all but some of the dependencies as to keep it aligned. The same can be done in other ways such as if using date constraints. Such model can be transferred to other software that would yield different leveled schedule if these links are not transferred. It will not tell the whole story about delay reason but will still be very useful.
I use the date constraints method to freeze resource leveling done by other software, this can be used to verify if the resource leveling is feasible. Please be aware not all software yield reliable resource leveling output, not common but happens.
http://www.planningplanet.com/forums/asta-powerproject/576477/asta-pp-resource-usage-plan
I would like to see delay reason shows delay as it currently does and not miss any resource, including materials and financial and that all delayed activities due to resource leveling are included. This without any mention of resource dependencies as this would be ambiguous. The delay duration or perhaps a date should be enough for the scheduler to pinpoint and investigate complex delay reasons.
Bogdan,
the problem with multiple resource dependencies: they may create an impression that all preceeding activities shall be finished for the current activity start. But they are of OR type. Resource dependencies are just the indicators that show where to pay attention. They are also useful for exporting leveled schedules to other projects.
Anoon,
Resource overloads may happen in any schedule including those with only FS0 dependencies.
Activities have logical dependencies but may be delayed when required resource is busy on another activity.
Analyzing resource constrained schedules we show why an activity is delayed if it is delayed more than logical links require. So we create and show resource dependencies that show what activities used the required resource and caused activity delay.
Activity sequencing is determining activity logical dependencies that must be followed. Resource leveling considers both these dependencies and availability of assigned resources and creates feasible schedule. PM software vendors automate this process and try to create the best possible (shortest) schedule. Manual leveling is possible but is very time consuming and rarely provides good results.
It seems I haven't made myself clear.
From what Rafael wrote I derived the ideea to keep resource dependencies as links between activities in the links table but to have on option to display (draw) these resource dependencies on the Graphic part of the Activity Gantt from resource asignment to resource assigments, Spider identifies these "links" (delays) in a tabular form in the column "Reason for delay".
For me, the resource dependencies between activities and the column Reason of delay is enough to drill down the schedule; what I would like in the Schedule report, if it is possible, to mention the amount of delay and the other activities that use the resource, for example:
Activity "Activity 3" (Code: 3) is delayed due to the lack of Resource "Resource A" (Code: A) from Activity "Activity 2" (Code: 2), for 24 hours, 3 days using calendar 8hd5wd.
Activity "Activity 3" (Code: 3) is delayed due to the lack of Resource "Resource A" (Code: A) from Activity "Activity 1" (Code: 1), for 4 hours, 0.5 days using calendar 8hd5wd.
Where the calendar 8hd5wd is the calendar is the calendar of the activity which is delayed.
I think this information would be very useful.
Best regards,
Bogdan
It is not possible to export assignment dependencies because they do not exist in other packages.
So the users have a choice if to export all dependencies including resource dependencies, or logical dependencies only.
In the first case their package will keep Spider schedule, in the second case it could not be guaranteed.
Rafael,
I have to agree with Vladimir, in the sense that drawing links between financiar and material constraints could be difficult to realize and somewhat abigous to read; however if I may suggest, as it is now, Spider draws resource links between activities, maybe it could be made in such a way as to draw resource dependencies between resource assignments or maybe an option to have both: in the Gantt settings there is an option called Resource dependencies, perhaps a sub-option called Draw resource dependencies at assignment level would prove more reliable when showing them; even perhaps draw them in the Resource Gantt diagram.
The functionality will imply only drawing the resource links at the assignement level, while maintaining them between activities in the links table, this way the export resource dependencies as links will not be affected.
Best regards,
Bogdan
Maybe there is still a way to show these multiple interruptions. Maybe an unorthodox idea such as creating temporary calendars and exceptions to represent the resource dependency can do the trick if there is a way to transfer such exceptions. Just a crazy idea in the hope something could come out of it. Never give up.
I have no problem whatsoever with how Spider works resource leveling. But when transferring resource leveled schedules to other software I have problems, I am looking for some workaround with the understanding these resource leveled schedules are a snapshot.
I believe Spider might have the required functionality to calculate the splits as calendar exceptions down to the seconds.
More challenging might be to transfer interruptions among different shifts on same activity.
For years I have been frustrated by how little functionality is on P6 that makes it impossible to mimic snapshots of more functional software such as Spider Project.
Even if some resource dependencies cannot be transferred to less functional software having access to them within Spider Project will be useful.
Rafael,
they do not model financing and supplies and delays are usually caused by delays of funding and supply.
And links may be complex because Spider Project schedule activities so that materials appear exactly at the moment when they were totally consumed. The link may lead to the middle of succeding activity.I am not sure that negative costs and materials can be exported to other tools.
But why not transfer delays caused by leveling of consumable as well as financial leveling?
I know most external software will not even recognize the existence of consumable and financial constraints but they are still relevant.
It is important for consistency and transparency that those receiving the Spider Project Schedule transfer get the delays caused by leveling of consumable as well as financial resources leveling. Maybe visibility will be available if consumable and financial resources are transferred as non-leveling regular resources along with their corresponding dependencies.
They might not be able to dream leveling consumable or financial resources but will be able to see what they are missing.
Rafael,
you remember that in Spider Project Resources are only rebewable resources.
Cost flow can be shown in the separate report where all cost "overloads" are shown like in this example
We do not special bar for materials "overloads" though material flow may be shown for any specific materials.
Resource dependencies are the result of resource constrained schedule analysis done after leveling. Resource dependency shows why an activity is delayed more than logical dependencies require. Besides they may be useful when Spider Project schedule is exported to another tool. One of the export options is exporting all dependencies including resource dependencies. In this case the schedule calcuated by external tool will be the same as the leveled schedule in Spider Project. We think that resource dependencies are useful for these two purposes: schedule analysis and schedule export. And once again by resources we always mean renewable resources.
You are right that it could be useful to show resource dependencies for portions of splitted activity.
Material dependencies are more complex. Next activity may start not only when another activity that consumed the same resource was finished but if its consumption rate became lower for some reason. In any case it is another task.
But what about materials/consumable and financial resource overloads?
As most construction schedules have materials/consumable and financial resource constraints I consider it a joke the claim these other software are good enough to efficiently handle resources.
The bar is against Spider itself.
In a prior post I said that the Resource Dependencies can be misleading and these are internal calculations that might be better if not shown. A 180 deg. turn from my request to display even more. Maybe the resource leveling algorithm does not make use of temporal links but temporal dates as I believe MSP does. If this is so why show something that is incomplete or not real?
Resource overload bar is the indicator of any resource overload.
Pressing right mouse button on the red area you will get the report on what resources were overloaded at that moment.
Resource peak workload calculation takes time and it is up to the user if to do it together with scheduling.
The warning of unsufficient resource quantity is shown when some activity requires more resource units that are available.
Resource peak workload shows the maximal number of resource required at any time, not only resource overloads.
did you press Resource Peak Workload button?
I might change my opinion about the bar as it will be a visual indicator of any overload, no matter what resource.
Thank you for the warning.
Best Regards,
Rafael
Rafael,
did you press Resource Peak Workload button?
Resource overload bar shows resource overloads after resource peak workloads are calculated.
You can set automatic calculation of peak resource workloads together with project scheduling in the scheduling/leveling options
I never trusted how resource dependencies are shown, perhaps enough for the software to level the schedule but not enough to show all dependencies.
Before leveling there are some overloads.
After leveling the so called Resource Dependencies can be shown.
The Resource Dependencies shown can be misleading. Activities 3 and 4 are delayed not only because of resources on Activity 1 but also because of resources on Activity 2.
The overloads report list all activities causing the overloads, this report is never misleading.
For the Resource Overloads Report to include materials/consumable resources as well as financial resources overloads is of much value, for me a big deal.
The following short videos showcase why I say Resource Overloads Bar can be misleading.
The ability to find out overloads using the overloads bar is sensitive to the time scale.
Even if the timescale is widened it still can be misleading as when multiple resources, each with their own overload events, each event with their own time span it is difficult if not impossible to figure it out where to click on the bar to hit each and every overload event.
The following scenario will showcase the difference between the diagams and the pre-defined overloads report.
The above diagram does not provide enough detail about the overload duration.
The above diagram is better but error prone and time consuming.
The above report give us the details up to the minutes, this is best report. There were two overload events, first lasted 1 hour and second 8 hours.
This report I want to be available for materials and financial resources.
BTW I am looking for the formula to calculate resource overload duration using resource calendar.
Email: PPadmin@planningplanet.com
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