Parallel path predecessors - OR RRS feed

  • Question

  • At the moment we're building a schedule which have multiple paths to completion. For example, any of two similar tasks (A or B) being completed, will trigger the next task (C) to start.

    Is it possible to use logic statements such as the OR statement, in predecessors, to allow the next task to start? Or is there a better way to achieve the same outcome?

    Thank you

    Thursday, November 26, 2015 12:11 AM

All replies

  • DaniePrinsloo,

    Sorry Project does not handle either/or type links. I suggest you set both tasks as predecessors to the third task. When the first task finishes, delete the link from the other potential predecessor task and that will trigger the third task to start.

    This could be implemented with some VBA but you would have to develop an algorithm to set up the desired either/or logic.


    Thursday, November 26, 2015 2:12 AM
  • Project planning requires estimates and assumptions. There is no escape from them, because you know less early and know more later. Estimates get refined as information becomes available. Assumptions are necessary but are retained only until they can be replaced with better assumptions, or certainty, such as actual facts that have actually happened in the past

    You must assume initially that A and B are both FS0 predecessors of C. Since either of them, but not both, might turn out to be the predecessor but you don't know which one it will be, this is the safe assumption. Then you carefully monitor and track the progress of A and B so that you can record after the fact, or, better, predict before the fact, which of A or B did or will finish first. Once you know this, and not before, you know which of A or B is the later finishing task and so should not be a FS0 predecessor of C, so that assumption can be dropped.

    MSP does not do what you ask, but nothing prevents you from having multiple "what if" versions of the same project plan.

    Any help.

    Thursday, November 26, 2015 2:34 AM