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How do I display resource-critical tasks? RRS feed

  • Question

  • I have a project where I have limited resources for each type of task. So I have only one software developer - every software development task has to be completed by her. So if, for example, I have ten 1-day tasks allocated 100% to this resource, with no dependencies, they should take 10 days to complete, and they do (with Resource Leveling on). But they don't show as Critical, even though to my mind they are critical (i.e. if one of them takes 2 days to complete instead of the planned duration of 1, then it will delay the end date of the project by one day).

    How do I get MS Project to show these tasks as critical, or to highlight them in some other way?

    Thanks - Rowan

    Tuesday, December 1, 2015 1:51 PM

Answers

  • Hi,

    Whilst the believers of CPM are right, I do understand Rowan's question and like him, I regret that Project does not recognize this "critical resource" thing. Telling him to link the tasks is IMHO a very bad idea. Yes, it colors the tasks red but it takes away the flexibility that the programmer can start working on either task and that is a high price to pay for a coloring on a chart.

    The true answer to his Original question is: sorry, Project can't do that.

    Greetings,

    Wednesday, December 2, 2015 3:17 PM
    Moderator
  • Hi Rowan,

    What you are looking for is the 'Resource-Critical Path'. I have published several articles on this (search for: 'Take the Path that is really Critical' and dedicated a chapter in my textbook 'Forecast Scheduling' on what to do when you experience resource-constraints. We even developed an add-in for Microsoft Project, called 'PathsPro', that can find the Resource-Critical Path in a workload leveled schedule.

    Eric Uyttewaal, ProjectProCorp

    Wednesday, February 27, 2019 8:38 PM
  • Eric,

    Welcome to Technet.  While the OP (Mr. Bradley) is long gone, it’s unfortunate that he left with an apparent intention to use soft logic (i.e. explicit resource ties, which Jan opposed) rather than relying on Project’s powerful leveling capabilities (as Trevor recommended).  I agree that the Resource Critical Path (sometimes called “Resource-Constrained Critical Path”) is in fact what he was after. 

    The three figures attached illustrate the concept for others.  The first chart shows a relatively simple project of four logical strings that could be completed in parallel if resources were unlimited (i.e. the “CPM” schedule).  The second chart shows the results of applying the default “Level All” method: explicit leveling delays are applied to six tasks, with cascading impacts on their successors.  The resulting schedule is resource-achievable.  The “Critical Path” identified by Project contains gaps, but it ignores the resource-demanding tasks that cause the gaps.  Our add-in (and yours, I believe) derives the Resource Critical Path by inferring resource-driving relationships between tasks that demand the same resource(s) in the leveled schedule.  For this example the third chart shows the Resource Critical Path in the top grouping and three successive near-critical groupings below it.  Typically, Total Slack is not at all corelated to the Resource Critical Path.  (In BPC Logic Filter, the bars of resource-driving tasks are cross-hatched, while those of logic-drivers are solid-colored.  I imagine the output from PathsPro is a bit more polished.)

    See you around, tom

    Thursday, February 28, 2019 12:59 AM

All replies

  • Rowan,

    The critical path is determined by tasks, not by resources. I'm having a little problem understanding how your single "critical" resource can work on tasks that have no links to other tasks (i.e. "no dependencies"). Getting those software tasks into the total network will quickly highlight their criticality, if indeed they are driving the end date.

    John

    Tuesday, December 1, 2015 5:00 PM
  • Imagine that you have a project where a builder must build 10 houses. The houses have nothing to do with each other - they are on different sites etc. Each one takes a year for the builder to build. As far as I can see, it will take 10 years to complete the project, but there are no dependencies (not between the individual houses, anyway). The builder can build the hosues in any order, or he can spend one month on each house in turn, but it will still take him 10 years to complete. That is the situation that I'm trying to represent. If I put in dependencies (e.g. from house 1 to house 2, from house 2 to house 3 etc.) to force it not to shedule the builder to build all 10 houses at the same time, finishing in a year, then if something delays house 2, houses 3-10 will show as delayed, but they should not be. The resource should switch to house 3 and avoid waiting for the problem with house 2 to be overcome.

    That is what I mean by resource-critical tasks. I would like to highlight all 10 tasks as being critical, because they all seem to meet the definition of "critial task" (i.e. a task which if delayed will delay the completion of the whole project), and need my attention as a project manager.

    Can I get MS Project to do this?

    Thanks - Rowan

    Tuesday, December 1, 2015 5:43 PM
  • RowanSBradley --

    Create 10 tasks, one for each house, and set the Duration to 10 years.  Assign the builder resource at a Units value of 10% on each task.  That would be one way to handle this, which would provide the flexibility for the building to work on any task any amount of time over the 10 years.  Perhaps the others in this group will have ideas for you as well.  Hope this helps.


    Dale A. Howard [MVP]

    Tuesday, December 1, 2015 6:24 PM
    Moderator
  • Rowan,

    I think you have mis-understood the critical path method, and you have co-opted the word "critical" to mean something other than what it means in the context of the method. The CPM has only two inputs, which are the task durations and the predecessor/successor relationships between them. Resources don't come into it. In effect, you could say that the CPM assumes resources will be available, although this is also not quite correct. It is not so much that resources are assumed to be available as much as resources simply don't come into it.

    In any project plan, it is essential to first establish the CPM network, which you have done, and you are correct to be reluctant to link tasks as predecessor/successor if they are not predecessor/successor just because of the resource limitations. Usually, without regard for the resource limitations, the overall duration of the project is very short and the tasks are all scheduled to start and finish very early ASAP. This is important information to start with but usually is not the end of the story, and not the final schedule solution.

    After this, you assign resources as required and discover that they are over-allocated, which means you now have a nice, short project but it is not feasible. So you level the resources, which delays some tasks and may extend the overall duration of the project and the earliest finish date.

    At this point, you have moved beyond the CPM, since tasks are now being scheduled by factors other than durations and predecessor/successor. Free Float and Total Float still has a meaning, but "critical" does not.
    Of course, the tasks that started out as critical are still critical.

    This point is often mis-understood, especially in the construction business, where it is apparently assumed, by lawyers, that the project schedule will always be the one revealed by the CPM, when in fact most projects have resource limitations.

    Do not have levelling running automatic, because it re-calculates at every edit.

    Tuesday, December 1, 2015 11:18 PM
  • Thanks for your replies. Maybe I have misused the term "critical path". But I still need to pay attention to the tasks that are forcing my project finish date to be what it is, i.e. preventing the project finishing earlier. These are the ones I need to look at every day, to see whether people are doing what they should be doing to complete the project as fast as possible. Therefore tasks that are limited by resources are just as important to look at as "critical" tasks If I can add some more resources to these tasks, or rearrange the tasks so they can take place at a time when there are spare resources, then I can advance my finish date. Therefore it would seem useful to me, to have in a project planning software tool, a facility to highlight these tasks. I guess you are all implying that MS Project (and possibly all other project planning software) does not do this.

    In which case I will have to make do...

    Thanks - Rowan

    Wednesday, December 2, 2015 1:12 PM
  • Hi Rowan,

    You need to set up predecessors for each activity, have them auto scheduled then on format tick the critical path box to turn all your critical tasks red and tasks with free slack, blue (Standard colour's)

    Hope that helps, mcilgrew

    Wednesday, December 2, 2015 3:05 PM
  • Hi,

    Whilst the believers of CPM are right, I do understand Rowan's question and like him, I regret that Project does not recognize this "critical resource" thing. Telling him to link the tasks is IMHO a very bad idea. Yes, it colors the tasks red but it takes away the flexibility that the programmer can start working on either task and that is a high price to pay for a coloring on a chart.

    The true answer to his Original question is: sorry, Project can't do that.

    Greetings,

    Wednesday, December 2, 2015 3:17 PM
    Moderator
  • Thanks for your further answers, and thanks Jan for understanding my position. I really think that using dependencies for this purpose is a total misuse of the facility, and a complete waste of time for the project manager. He will continually be having to insert and remove and change these "false" dependencies, and runs the risk that the project is constrained by a false dependency that is (falsely) delaying the end of the project.

    The strange thing is, I'm sure that in the past I have used a project planning package that got this right. The only packages that I have used seriously are MS Project and CA Superproject (many years ago), so (if I am remebering correctly) one of them can (or could in some previous version) do this.

    If there is some agreement that this is a worthwhile feature, can we get it on the wish list for features in future versions of MS Project?

    Thanks - Rowan

    Wednesday, December 2, 2015 3:27 PM
  • Rowan,

    Okay, here's a little different approach that may (or may not) help with the type of planning you want. In creating this mock-up I admittedly have violated a best practice rule of Project (i.e task descriptions are not definitive). However, the basic principle is that instead of grouping all of a particular resource's tasks into a single or series of fixed duration tasks this approach defines a set of individual generic tasks that are linked finish-to-start.

    In the example software developer July has three tasks and hardware designer Bob also has three tasks. Judy's three real tasks are: code module 1, code module 2 and code module 3. It doesn't matter which module Judy works first, second and third so the schedule simply calls them: Judy-1, Judy-2 and Judy-3. Bob's effort is similar.

    To create a critical path the generic tasks are linked because each task is dependent on a single resource and that resource can only work one task at a time. The final task of both resources are linked to follow on tasks that go on to define the project completion. As each resource completes a task, the generic task for that day is credited as being complete.

    In the first screen shot, the original plan is shown. Every task is critical.

    In the next screen shot both Judy and Bob completed their first day tasks, however on the second day Judy was involved in a minor traffic accident and didn't get to work until noon so she could only finish half of her second task. The resulting slip show's the impact to the overall plan.

    Anyway, something to consider.

    John

    Wednesday, December 2, 2015 4:15 PM
  • John,

    Thanks for this suggestion. This may well be a good workaround or compromise. If the tools available require this sort of approach then that;s what I will have to do. I am just surprised and disappointed that this is necessary with a modern project planning package.

    Thanks - Rowan

    Wednesday, December 2, 2015 4:21 PM
  • Rowan,

    You're welcome and thanks for the feedback.

    No software package will do everything everyone wants so sometimes the best you can do is pick one that does most of what you want/need and then modify your wants/needs or use some out-of-box thinking to get what you want/need. However when you use a product for something it's not intended or beyond its capabilities, vigilant care is needed - obviously.

    John

    Wednesday, December 2, 2015 4:30 PM
  • Hi Rowan,

    What you are looking for is the 'Resource-Critical Path'. I have published several articles on this (search for: 'Take the Path that is really Critical' and dedicated a chapter in my textbook 'Forecast Scheduling' on what to do when you experience resource-constraints. We even developed an add-in for Microsoft Project, called 'PathsPro', that can find the Resource-Critical Path in a workload leveled schedule.

    Eric Uyttewaal, ProjectProCorp

    Wednesday, February 27, 2019 8:38 PM
  • Eric,

    Welcome to Technet.  While the OP (Mr. Bradley) is long gone, it’s unfortunate that he left with an apparent intention to use soft logic (i.e. explicit resource ties, which Jan opposed) rather than relying on Project’s powerful leveling capabilities (as Trevor recommended).  I agree that the Resource Critical Path (sometimes called “Resource-Constrained Critical Path”) is in fact what he was after. 

    The three figures attached illustrate the concept for others.  The first chart shows a relatively simple project of four logical strings that could be completed in parallel if resources were unlimited (i.e. the “CPM” schedule).  The second chart shows the results of applying the default “Level All” method: explicit leveling delays are applied to six tasks, with cascading impacts on their successors.  The resulting schedule is resource-achievable.  The “Critical Path” identified by Project contains gaps, but it ignores the resource-demanding tasks that cause the gaps.  Our add-in (and yours, I believe) derives the Resource Critical Path by inferring resource-driving relationships between tasks that demand the same resource(s) in the leveled schedule.  For this example the third chart shows the Resource Critical Path in the top grouping and three successive near-critical groupings below it.  Typically, Total Slack is not at all corelated to the Resource Critical Path.  (In BPC Logic Filter, the bars of resource-driving tasks are cross-hatched, while those of logic-drivers are solid-colored.  I imagine the output from PathsPro is a bit more polished.)

    See you around, tom

    Thursday, February 28, 2019 12:59 AM