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Im new to project and im trying to link task 2 to a activity in task 1 so that all of the earlier activities in task 2 then work backwards. I have read that i should be using "as late as possible" rather than using the SF dependencies and then linking all the tasks in reverse. This makes sense as having to write SF on every line item is extremely time consuming. Unfortunately im having some issues trying to implement it.

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Ive set "Sub Task 2d" to start as late as possible and SS with "Sub Task 1c". I understand that SS means task B cant start before Task A has started, and its taking "Sub Task 1e" as the last project date, so its finishing then.

When i change this to SF, and keep "as late as possible" i though SF meant Task A must start before Task B can finish, so why hasnt Task B (Sub Task 2D) moved earlier so its finish time coincides with the start of Task A (Sub Task 1C) and Sub Task 2A-2C also then moved earlier due to Sub Task 2D moving??

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Any help would be much appreciated.

$$ Edit $$

The following seems to work but im not sure if this is a bad practice. Sub Task 2d has predecessors set as 12sf,6sf and its set to ASAP. All other Sub Task 2 activities are set to ALAP.

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    Haven't you answered your own question? The SF link says 2d can't start until 1d is finished. 2d's ALAP constraint also forces it to the right as far as its successors (it has none) allow. Most of the time, neither SF nor ALAP are consistent with good scheduling practice; I avoid them.
    – Tom Boyle
    Commented Apr 26, 2020 at 17:15
  • id obviously been look at this for too long :( One solution to my problem is to set "Sub Task 2a-2c" as "ALAP" and set "Sub Task 2d" to "ASAP" with it finishing after "Sub Task 1d" & "Sub Task 2c". Is this the correct way of doing this? Ive included an edit in the original question.
    – Hans Rudel
    Commented Apr 26, 2020 at 21:24
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    To your comment (not the edited question) that's not the solution. Setting 2a-2c to ALAP will automatically force 2d to the right as well, the same place it is now. (In MSP, ALAP functions as a zero-total-float constraint, not zero-free-float which you may be seeking. Although many people seem to use it otherwise, ALAP only makes sense in backward scheduling, IMO.)
    – Tom Boyle
    Commented Apr 27, 2020 at 1:36
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    To your edit, since you are essentially date-manipulating at this point, just type in the dates and be done with it.
    – Tom Boyle
    Commented Apr 27, 2020 at 1:37
  • Not sure i follow the "Zero-total-float" comment? The problem i have with setting fixed dates is that im scheduling for 5 vessels and id like to link them in a similar way above as certain activities, ie the pigging and pressure test of the pipeline can only occur after its been laid. Thanks again for your help thus far, i really appreciate it. hope you had a great wknd.
    – Hans Rudel
    Commented Apr 27, 2020 at 7:27

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As noted in the comments, neither SF links nor ALAP constraints generally satisfy the need for scheduling just-in-time work. This figure shows a new readiness milestone linking to a new lead-time activity. (The lead-time activity is needed only for delaying multiple tasks together. For just-in-time shipment/delivery, only the milestone is needed.) Not perfect, but fairly robust and gets the job done without destroying logic flow. enter image description here

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