When we first start learning how to use P6, understanding the basics of schedule logic is a must. You let the program determine activity dates for you, rather than calculating them yourself, because you’re just getting a good grasp of how the software can make scheduling easier for you. In P6, the schedule and critical path is calculated from the calendars, durations, and relationships that you set-up in the project. Rather than allowing P6 to automatically calculate dates, you have the option determine dates and override what P6 “thinks” the schedule should look like. In this article, we will look at the different options P6 makes available to you to determine your scheduled project dates.
RETAINED LOGIC
In essence, P6 will respect the relationships you have set-up in the schedule when you are using Retained Logic. Retained Logic is the first setting we learn how to use in P6 when we’re just starting out with the software. You’ll enter dates, durations, relationships, and calendars, and P6 will spit out the schedule it “thinks” is right based on the variables you have provided. In this case, predecessor activities must be completed before successor activities can start.
Why would you use it?
1) It’s an industry-standard and best practice used by more companies – most stakeholders want to see the “worst-case scenario” using in-sequence activities as the project would most likely occur.
2) It does not allow successor activities to start before predecessor activities finish, creating a realistic picture of the project.
Warnings?
Retained Logic will not account for real out-of-sequence activities that happen on-site. In reality, activities may start out-of-sequence because it was possible to. You’ll end up having to fiddle with P6 to recognize these out-of-sequence activities in your schedule.
PROGRESS OVERRIDE
If you’re using Progress Override, P6 will no longer respect the network logic you have previously set-up. Rather, it will calculate the remaining duration of the activities out-of-sequence. This means that that an activity will start before their predecessor has finished in a finish-to-start (FS) relationship, which is out-of-sequence.
Why would you use it?
1) You can find out-of-sequence activities quickly by using the Schedule Report or reviewing your schedule on the Gantt Chart.
2) It can reflect real-life scenarios by showing out-of-sequence activities that happen on on-site.
Warnings?
Progress Override creates a positive outlook on the project. P6 will assume that activities that can happen out-of-sequence will happen out-of-sequence. If the out-of-sequence activity is delayed, then your project is behind.
ACTUAL DATES
If you’re scheduling using Actual Date, you guessed it, you’re manually entering the actual dates of the activities. This is time consuming and can lead to human errors due to increased manual input. Also, it means that you’re not using Primavera P6 to its maximum capacity, which is to calculate and manage your project for you.
Why would you use it?
1) You want to manually input the schedule dates.
Warnings?
You’ll most likely spend so much time entering dates that you’ll miss issues on-site that could delay your project.
HOW TO SCHEDULE USING PROGRESS OVERRIDE AND RETAINED LOGIC
Step 1: Open Tools Menu > Schedule (or press F9).
Step 2: In the Schedule dialog box, select Options.
Step 3: In the Schedule Options,select the circle beside Retained Logic or Progress Override. Click Close.
Step 4: In the Schedule Dialog box, click Schedule.
Please let us know if you have any questions or comments about using Progress Override versus Retained Logic!
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