Schedule Calculation Mode?
In the Open Standard
Sukumaran SubaramaniyanMember for 21 years 7 months
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What is the best mode to calculate the schedule?
Is it:
a) Retained Logic, or
b) Progress Override
As mentioned by P3:
1) Retained Logic - P3 does not schedule the remaining duration of a progressed activity until all of its predecessors are completed.
2) Progress Override - P3 ignores network logic and allows the activity to progress without delay.
When run the updated schedule with both calculation mode, there are some noticable changes on:
a) Number of activities in longest path
b) Latest calculated early finish date
c) Total float
Obviously using progress override, delay has been reduced and positive floats have been increased. But some editing on links are required when the successors are completed ahead of predessors. Where the predessors need to be re-linked to the nearest activity when the late finish date is overshoot the logical sequence.
Please advise for the best method to calculate the schedule.
Regards.
Is it:
a) Retained Logic, or
b) Progress Override
As mentioned by P3:
1) Retained Logic - P3 does not schedule the remaining duration of a progressed activity until all of its predecessors are completed.
2) Progress Override - P3 ignores network logic and allows the activity to progress without delay.
When run the updated schedule with both calculation mode, there are some noticable changes on:
a) Number of activities in longest path
b) Latest calculated early finish date
c) Total float
Obviously using progress override, delay has been reduced and positive floats have been increased. But some editing on links are required when the successors are completed ahead of predessors. Where the predessors need to be re-linked to the nearest activity when the late finish date is overshoot the logical sequence.
Please advise for the best method to calculate the schedule.
Regards.
5 replies
Oldest first- 0Shahzad Munawar ·The best mode to calculate the schedule is Progress Override despite u are using Retained logic because by using this method delay will be reduced with some modifications in links and this method is most commonly acceptable to the Consultants also for schedule calculation.
- 0Brennan Westworth ·I would argue that retained logic is the way to go, logic links are there for a reason... not to just get the activity to sit in the right time period.
if your sucessor is starting before the predecessor is complete the relationship must be SS/FF with some lag. If you use progress override your schedule will show you completing the sucessor before its predecessors are complete.
reguardless of which method you use, you should always keep an eye on out of sequence progress. - 0Kamran Hazini ·I agree with Brennan. I believe by using progress override we just closing our eyes on activities that are progressing out of sequence. Of Course we will produce some positive floats in our schedule but do our activities really taking place in the right order? The result, at least in my opinion, would be revisions in already issued documents and lots of re-works in this case.
Even if we have not defined the relation type correctly at the beginning, still we can keep the mode Retained Logic and just modify the relation type wherever logic has problem. - 0Frank Borcherdt ·I also agree that retain logic is the better/safer option for the following reasons:-
1. progress override introduces float on the predecessor out of sequence activity from its calculated end date to the end of the project (unless there are other successors to this activity). This means you may stop monitoring this activity as closely as it has dropped off the critical path.
2. progress override is the best case scenario and assumes you can continue with the successor out of sequence activity and this may not always be the case and the delay may push critical dates…you will be blissfully unaware until the next reporting cycle.
3. Retain logic is the worst case scenario and if it pushes a critical date you will find this activity and can still make the decision to remove the relationship if it genuinely if no longer required.
I agree that you should review the out of sequence activities however when we are under time constraints we tend to report as soon as we can confirm that progress appears accurate and the critical dates are still being met.
If the project has changed so that the original logic no longer reflects the way you will execute the work then I would recommend spending the time to revise the plan otherwise you are truly “flying blind” and the plan is of little or no use to you and will possibly become a contractual liability as well.
- 0Bernard Ertl ·
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