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MSP - Critical Path RRS feed

  • Question

  • Hi All,

    In MSP, I believe that critical path calculation should NOT consider summary task. However I am not sure how it is being calculated in MSP.

    I am looking forward to hear your thoughts for:

    1. Do you agree that critical path calculation should NOT consider summary task.

    2. Does MSP 2016 automatically ignores the summary task while calculating the critical path?

    3. What is the best practice to let the system know NOT to consider summary task in critical path calculation?

    Looking forward to hear from experts.

    Thanks,

    Namita Mishra

    Thursday, November 22, 2018 6:31 AM

All replies

  • Just have a look at the schedule table and see what tasks, milestones and, yes even summaries, have got zero total float (slack in MSP), which is the definition of "critical", in the right most column. Any summary that has critical tasks in it will have zero total slack also, so you could say that it is critical (but that is stretching the definition). However, when you check the box for critical tasks to make the critical tasks red, all that MSP does is adds one new row in the bar styles. It does not add in rows for "critical milestones" or "critical summaries". But there is nothing to stop you from putting those rows in so that you will see red summaries bars and red milestone diamonds. I do it all the time. It is handy, because if the summary is red you know that there will be tasks in there under it that are red. However, don't attach any meaning or significance to it because a summary is not a task, and should never have predecessors or successors. Do you know how to edit the bar styles? Would you like to see an example? (I have one in front of me right now).
    Thursday, November 22, 2018 7:19 AM
  • Hi,

    Thanks for the quick response and also for the offer to show the example.

    I am very new to MSP and would certainly like to see the one that you have prepared.

    Thank You!!

    Namita Mishra

    Thursday, November 22, 2018 7:50 AM
  • Hi Trevor,

    It would be good if you can please share the example. It will help in understanding.

    Basically one of the team members mentioned that there should be a way to exclude the summary tasks in critical path calculation. I do not find any option in MSP for the same.

    From your response - "However, when you check the box for critical tasks to make the critical tasks red, all that MSP does is adds one new row in the bar styles. It does not add in rows for "critical milestones" or "critical summaries". " - It looks like that MSP by default does NOT consider milestones / summary tasks in critical path calculation. Is this correct understanding?

    Thanks!

    Thursday, November 22, 2018 11:03 AM
  • Hi Trevor,

    I found how to update the bar styles and in fact successfully marked summary task bars red if they have critical task underneath them. 

    However, same is not working for Milestones. Please refer "Critical Milestone" entry in the attached screenshot. For milestone,

    Name: Critical Miestone

    Appearance: Red Diamond

    Show For .. Tasks: Milestone,Critical,Active,Not Group By Summary

    Row: 1

    From: Task Start

    To: Task Start

    Thursday, November 22, 2018 1:06 PM
  • Namita,

    Trevor may be counting sheep right now, so let me jump in with some info.

    Very likely those particular milestones are NOT on the critical path. Add the Total Slack field to the Gantt Chart view. Tasks/milestones on the critical path will show 0d total slack.

    With regard to your previous post (earlier today), summary lines and milestone are NOT tasks. A summary line is simply a summation of metrics of all the subtasks under it. Milestone are a point in time marking the start or completion of one or more tasks.

    Hope this helps.

    John
    Thursday, November 22, 2018 4:08 PM
  • Namita Mishra,

    1. Correct: the Critical Path does not include summary tasks or hammocks.
    2. MSP (2016 and other) does NOT compute the “Critical Path.”  It identifies “Critical” tasks, which are not always consistent with a specific logic path.
      1. MSP assigns the “Critical” flag to all tasks (including summary tasks and milestones) based on their Total Slack.
      2. Total Slack is computed as the difference between a task’s Early and Late dates.
        1. Early and Late dates for sub-tasks and milestones are computed from the logic network.
        2. Early and Late dates for summary tasks are inherited from their (different) sub-tasks, which may or may not be logically connected.  Consequently, Total Slack of summary tasks has no valid meaning, and application of the “Critical” flag is equally invalid.
        3. Adding logic to summary tasks complicates both of these.  Don’t do it.
    3. Make a “Critical-Non-Summary” filter to exclude summary tasks.

    Good luck, tom

    Thursday, November 22, 2018 5:30 PM
  • Here are some red summary bars and red milestone diamonds.

    Friday, November 23, 2018 1:48 AM
  • ... and here are the styles. "The show for.." for the respective red ones is identical except with the "critical" condition tacked on. And note the new row must be lower in the list because MSP reads from the top of the list down so that the one lower in the list overwrites the one higher.

    Friday, November 23, 2018 1:54 AM