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Is Retained Logic the best Scheduling Option in Primavera?

Written by Amit Parmar

15 Comments

Primavera has three Scheduling Options to choose

from when you are scheduling your project. Retained

Logic is the default scheduling option. When you are

building a Baseline, the default option works fine. But

things change when you start updating your project, activities start getting delayed and do not get executed as

planned.  You then have to make a decision on whether you want to continue using Retained logic or choose Progress

Override or Actual Dates as your Scheduling Option. A lot has been discussed over the internet forums on which option is

the best for a project and Retained Logic has won with an overwhelming majority. But I have a different opinion.

Has your project ever followed the exact logic that you planned in your baseline?

If your project has followed the exact logic as planned in your baseline then you are an awesome planner and you don’t

need to read this blog post any further. But in my experience, on most of the projects activities don’t get executed

exactly as planned in the baseline. Some start earlier than planned, some start later than planned and some might get

delayed during execution. This is where Scheduling Options in Primavera play an important part. Choosing different

scheduling options changes the way Primavera’s scheduling engine executes its calculations for Forward Pass and

Backward Pass. This then changes the way dates are calculated for the activities in your project and it has an impact on

your completion date.

The three scheduling options available in Primavera are:

1. Retained Logic

2. Progress Override

3. Actual Dates

For this post let us assume 3 activities with names; Activity A, Activity B, Activity C. They are connected by a Finish to

Start (FS) relationship. We will update them out-of-sequence and schedule our project with all the three scheduling

options and see what impact does it have on our project.

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1) Retained Logic – assumes that you wish to Retain Logic of your relationships when you are scheduling your project.

This means that the remaining duration of an in-progress activity is not scheduled until all predecessors are complete.

Retained Logic- Retains the logic of your relationships while scheduling the project

Let’s take a look at an example and see how this works. We have updated our activities out-of-sequence on the following

dates:

You can see above that Activity B has been updated out-of-sequence but Activity A is still in progress. We then choose

Retained Logic as our scheduling option and schedule our project.  Due to Retained Logic, Primavera assumes that we

are retaining the logic of relationships between our activities even though the activities are being updated out-of-

sequence. This means that Primavera calculates the Remaining Start of Activity C as per Finish-to-Start logic with

Activity A (and not Activity B).  This makes Activity C non-working between the period of 1-Feb-15 to 5-Feb-15. The non-

working period can be seen in the Gantt chart below:

 

Lets review the calculations for this example; the Data Date for our project is 1-Feb-15. The scheduling engine calculates

that for Activity A Remaining Early Finish is 06-Feb-15, due to this the Remaining Early Start for Activity C is calculated to

6-Feb-15. The scheduling engine is told to retain logic for the relationships and picks the Remaining Early Start for

Activity C after Remaining Early Finish of activity A because Activity B is already complete.

The non-working period calculated due to Retained Logic can be misunderstood as, no work will be performed on

Activity C between the time period of 1st Feb-15 and 05-Feb-15. This non-working period also adds an extra 5 days to the

completion of the project. Now, the purists can make an argument that in such cases we should change the logic of the

activity because the logic has actually changed. But if your contractual obligations do not allow you to make changes to

your current project without approval of the client then it might force you to keep your relationships fixed and decrease

the Remaining Duration on the activity to adjust the non-working period.

2) Progress Override – this scheduling option assumes that network logic can be ignored in case of out-of-sequence

activities and the remaining duration of the activity can be scheduled without delay. This means that Primavera’s

scheduling engine will ignore the relationship logic between the activities and schedule the activities without any non-

working periods.

Progress Override – Assumes that relationship logic can be ignored for out-of-sequence activities

For our example this means that, Activity C will not have a non-working period and the remaining duration of the activity

will be scheduled from the data date of the project as seen in the screenshot below.

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Lets review the calculations for this example: The Date Date for the project is 1-Feb-15. The scheduling engine calculates

that for Activity A Remaining Early finish is 6-Feb-15 and Activity B is completely finished. Due to this the Remaining

Duration of  Activity C is scheduled from 1-Feb-15 and the relationship logic from Activity A is ignored. Since there is no

non-working period in Activity C, it finishes on 19-Feb-15.

It is clear from the above example that Progress Override reduces the project duration by 5 days by not adding the non-

working period. This seems logical according to the work that is being done on the project as you might be working on 

Activity C continuously and unlike Retained Logic there will be no non-working period.

3) Actual Dates – this scheduling option uses the Actual Dates for Forward Pass and Backward Pass calculations.

 Actual Dates – Uses the Actual Dates of the activity for Forward Pass and Backward Pass calculations

When you choose Actual dates option, the scheduling engine does the forward pass and backward pass based on the

actual dates. This means that you can update an activity with an Actual Start and Actual Finish after the Data Date and

Primavera will schedule the successor activities based on the actual dates of the activity. For this example we will finish

Activity B after the data date of the project.

In the above screenshot we can see that the Data Date (Blue line) is 1-Feb-15 which is before the start of Activity A but

Activity B has finished on 14-Feb-15, after the Data Date. Activity C is then scheduled after finish of Activity B and starts on

14-Feb-15.

Lets review the calculations for this example: The data date for the project is 1-Feb-15. Activity B has finished on 14-Feb-15

but both Activity A and Activity C are not progressed. When we schedule our project on 1-Feb-15, the scheduling engine

schedules Activity A from 01-Feb-15 (data date) as the activity has no predecessor but Activity C is scheduled from 14-

Feb-15 because Activity B has an actual finish on 14-Feb-15. This method eliminates the out-of-sequence logic from the

project.

Actual Dates option can be used to fix dates for activities which you know will happen in future for sure.  It can be used in

situations when we know that an activity will for sure finish on fixed dates and we want to schedule the successor

activities after that actual date. While this sort of thing doesn’t usually happen on projects, we can use this option

to prepare some what-if scenarios.

After looking at the above examples, we now know that Retained Logic and Progress Override are the two main options

that we can use to schedule our projects. I prefer using Progress Override over Retained Logic for scheduling on my

projects because I know it represents the actual scenario. It doesn’t add non-working periods to projects and potentially

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            1 Vote

extending their duration. I know a lot of my readers will think otherwise, please comment below if you don’t agree with

my justification.

 

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visit the Forums section for any discussions.

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actual dates progress override retained logic scheduling options

Amit

August 3, 2011 at 8:30 am

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Hi Amit,

Good to see your polls, very knowledgeable and informative.

Here I would like to submit my opinion for aforementioned scheduling options and like to have your

suggestions.

When we say ‘development of schedule’ and its ‘tracking or monitoring’, following three items we need

to takecare.

1. Dependencies (Relationships Or work/business/engineering processes).

2. Plan Phasing-out methodology, (Execution Aproach).

3. Schedule update mechanism.

We have three scheduling options for the ease of users, and depends upon user’s proficiency on his

subject/project.

Actual Dates: If we use this option, least chances to have correct forecasting.

Progress Override: One side at the time of ‘planning/defining relationships/defining dependencies’ we

said to PRIMAVERA to use such logic for the forecasting of schedule and on the other side we want from

PRIMAVERA to overide the defined logics.

Retain Logic: To use this option our schedule must comply with correct work/business/engineering

processes, the execution strategy must be reflected in schedule and must have detailed schedule in

3/18/2015 Is Retained Logic the best Scheduling Option in Primavera? | PrimaveraBlog, Tutorials, Project Management, P6

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Primavera.

Planning methodology is the key for development/forecasting of schedule. While developing a project

schedule use work/business/engineering processes for technical schedule and use constraints to add

managerial component for phasing-out the schedule viz. Drawings, Procurements, fronts, commissioning

etc.

I would like to use Retain Logic.

However it depends what aproach we used for schedule development to choose one out-off three

options.

Amit

Amit Parmar

August 3, 2011 at 1:56 pm

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Hi Amit,

I do appreciate that Retained Logic is your choice. But what do you do in case some activities do

not follow logic and one of your activities has a non-working period in it?

1)Will your project manager agree that he will not be working during that time period?

2)Will he agree to the delayed finish due to that non working period?

3)How will you incorporate this time period in your current schedule?

4)Do you also change the baseline when you make changes in your current schedule?

These are the kind if questions that come in my head when I think of choosing retained logic. How

do you solve these problems when you are managing your project?

Amit

Susan

August 3, 2011 at 2:47 pm

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@Amit P

How about using ‘Retained Logic’ & updating the relationships in every update to reflect the actual

situation ? Would that help solve your concerns about ‘non work periods’ etc ?

Susan

Amit Parmar

August 3, 2011 at 5:08 pm

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Hi Susan,

The method that you are saying is correct and we can remove the non-working period by changing

the relationships. But how do we justify the change in the logic and change from the baseline?

Before changing our logic from the baseline we also have to consider the contractual implications

that it would have. If that doesn’t matter then you can go ahead with it. but believe you would not

immediately come to know which activities are working out of sequences especially when you are

working on a large project of say 5000 activities and too many activities are in progress.

Amit

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Syed Haneef

September 12, 2013 at 4:22 pm

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Yes, I think that is the way to solve this. modify activities relationships to reflect the actual situation

at Project.

Susan

August 5, 2011 at 2:56 pm

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@Amit P,

‘How do we justify the change in the logic & change from baseline’ – well the argument would be that

‘Progress override’ function does just that !!

By choosing the override function you are disregarding every assumption of the baseline anyways. You

cant do a what-if either, analysis unless retained logic + updating the links is chosen.

Regarding the activities that have chnged & the general pulse of the project activities – even if they run

in thousands, I guess Primavera has proceeded to make the life easier with P6V8 series.

Susan.

Amit Parmar

August 6, 2011 at 12:05 pm

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Well, you are right and in both the cases we do change the logic from the baseline. Doing a what-if

on ‘out of sequence’ activities with retained logic is anyways difficult. How would we justify a non-

working period in the what-if in case actual progress is happening on site?. We are currently trying

to do the same on our current project and facing the dilemma of using Retained Logic or Progress

Override for What-ifs.

Amit

Azman

October 20, 2011 at 7:58 pm

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Hi all, handling OOS using retained logic, what are the particular(s) that you fix ? e.g. do you remove the

relationship that causing it or you modify the lag? What is the implication of it to the critical path if any.

Thanks.

Amit Parmar (PMP)

October 21, 2011 at 9:43 am

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Hi Azman,

Removing a relationship or modifying the lag depends on the way the relationship has changed

between the activities. Usually it is the lag that gets changed, but if you have not planned it well

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initially then there are chances that the relationship gets removed. And as far as implication on the

critical path goes, that also depends on your network and you will have to analyze that after you

modify the relationships.

Regards

Amit

Anu

June 26, 2013 at 6:20 pm

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Hi Amit,

Thank you so much for the info. on Scheduling options.

Anu

Anu

August 20, 2013 at 4:07 pm

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Hi Amit,

Thank you so much for the breif description on Scheduling Options.

In my schedule,I came acrossed the same situation i.e for example,the prdecessor activity of B is

completed and successor activity is in progress.And the total float is showing as positive. Can u pls tell

me how to overcome this issue.PMC is saying to change lag or relationship.but,nothing worked.

Practically,that activity B is critical.

Pls suggest what to do in this case.

Thanks in advance for ur reply.

Anu.

Amit Parmar (PMP)

August 23, 2013 at 3:48 pm

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hello,

Can you send me a screenshot of the activities where you are getting this problem. As your

description is not that clear, I am unable to get the problem.

Thanks

Amit

abbas

September 13, 2013 at 10:55 am

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Dear Amit,

I have schedule Baseline and iam updating with actual ,now the project is delayed the cleint is insisting

me to send the revised baseline ,can u please suggest me to prepare revised baseline and how to add

original baseline ,revised basline and actual in a same sheet in primavera ,plz iam a beginner in

primavera

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ACTIVITIES ACTIVITY % COMPLETE ACTUAL COST ACTUAL DATES ACTUAL DURATION ACTUAL UNITS ADMIN PREFERENCES BAC BUDGET AT

COMPLETION CONSTRAINTS CPI DATA DATE DURATION % COMPLETE EARLY FINISH EARLY START EARNED VALUE EARNED VALUES

CALCULATIONS EPS ESTIMATE AT COMPLETION ESTIMATE TO COMPLETE EXPECTED FINISH FINANCIAL PERIODS GLOBAL CHANGE MANDATORY START / MANDATORY FINISH

P6V8 PHYSICAL % COMPLETE PLANNED VALUE PLANNED VALUE COST PRIMAVERA PROGRESS OVERRIDE PROJECT PROJECT MUST FINISH BY RESOURCE LEVELING

RESOURCES RETAINED LOGIC SCHEDULING SCHEDULING OPTIONS SPI START / FINISH ON OR AFTER START / FINISH ON OR BEFORE SUMMARY TOTAL FLOAT UNITS %

COMPLETE WBS

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Amit Parmar (PMP)

September 20, 2013 at 1:33 pm

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Hello Abbas,

You can add the current project as a Baseline and allocate it as Primary baseline. Then prepare a

revised schedule on it. You have options to enable dates column for Primary, secondary and tertiary

baseline. So all the dates can me compared side by side.

Amit

svkumar

November 17, 2013 at 11:26 pm

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i Would propose. retain logic should be followed while progress Eng phase and progress override while

doing construction

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