Before you just hit F9 <enter> … There are many options under the Schedule Options Tab that you should review that may make a difference in the outcome of your schedule calculations. Below is a brief review of the options.
- Ignore relationships to and from other projects – relationship can be formed between 2 or more projects when they are opened together. This option, if checked, allows you ignore those relationship if the other project are not opened. Keep unchecked if you want to maintain the relationships.
- Make open-ended activities critical – makes the late date equal to the early date for activities that do not have successors. This can be very useful if the user would like to display and analyze multiply critical paths without using constraints.
- Use Expected Finish dates – calculates the remaining duration for both un-started and in-progress activities. Typically this is option is checked on.
- Schedule automatically when a change affects the dates – if checked the schedule will update automatically if a change is made to timing of the schedule. This is similar to how other scheduling products work. This could be very time consuming if the schedule is large with many logic ties. Typically this option is not checked.
- Level Resources during scheduling – this option is used to level resources in a schedule and should only be used in what-if scenarios. It can provide valuable information that can then be used to change logic that would level resources. It is recommended that this option not be used as common practice.
- Recalculate assignment costs after scheduling – resources can have different rates assigned across time periods. This option will recalculate costs for a resource that has multiple rates across the time periods based on the rescheduled activity if it falls into another rate band. An example of using this option would be preparing a time-based estimate where the resources have an annual escalation built into the rate table.
- Retained logic and progress override – when an activity has started before its predecessor has finished an “out-of-sequence” progress occurs. There are 3 options to choose for determining how P6 will calculate the finish date of the successor activity.
- Retained Logic (the recommended option) – the relationship is maintained between predecessor and successor and unworked part of the activity will be scheduled to continue after its predecessor is completed. The relationship forms part of the critical path and predecessor has no float.
- Progress Override – the relationship is ignored between predecessor and successor and unworked part of the activity will be scheduled to continue before its predecessor is completed. The relationship does not form part of the critical path and predecessor has float.
- Actual Dates – this option works when there is an actual start date in the future (which is not really logical). The remaining duration of an in-progress activity will be scheduled to progress after the predecessor’s actual start and finish dates. If there are no actual dates in the future, then the schedule defaults to calculate with retained logic.
Note: Retained logic is the recommended option because it calculates the most conservative schedule (longer duration). Also many government agencies require this options as part of their specifications. This option requires a closer review by the Schedules to see if adjustments to the relationships should be considered.
- Calculate start-to-start lag from – determines the start date for a successor that has a SS relationship with a lag.
- Actual Start – the successor starts with the lag based on the actual start of predecessor. This gives a less conservative schedule.
- Early Start – the successor starts with the lag based on the early start of predecessor. This gives a more conservative schedule.
- Define Critical activities as – defines the criteria for critical activities in the schedule:
- Total Float less than or equal to – activities will be marked as critical if their total float value is less than or equal to what that is defined here.
- Longest Path – critical activities are defined as the longest chain of activities in the schedule. Use this option when multiple calendars are in use.
- Calculate float based on finish dates – when more than one project is opened, this options determines if float is calculated on each individual project’s finish date or the longest project’s finish date.
- Compute Total Float as – these options determine the float value that is displayed for WBS and LOE activities only.
- Start float = late start – early start
- Finish Float – late finish – early finish
- Smallest of Start Float or Finish Float
Note: The total float bar only displays for the Finish Float
- Calendar for scheduling Relationship Lag – Specifies which calendar to use for calculating relationship lags.
- Predecessor activity calendar – uses the predecessor’s calendar
- Successor activity calendar – uses the successor’s calendar
- 24-hour – uses a 24 hour calendar
- Project default calendar – uses the project’s default calendar defined under the Project Default
The Advanced Tab offers a great way to further analyze the critical path/s of the schedule. It allows you to calculate multiple float paths (the most critical activities and subsequent sub-critical activities) and to display them in a banded picture that is very useful for analyzing large projects. Choose between Total Float or Free Float:
Total Float: Based on the activity you want the paths to end on, P6 determines which predecessor activity has the most critical Relationship Total Float on the backward pass. This process repeats until an activity is reached that has no relationship. P6 begins the forward pass from this activity and determines which successor activity has the most critical Relationship Successor Total Float. These activities represent the most critical float path. The process begins again until the remaining sub-critical paths are calculated. 1
Free Float: Defines critical float paths based on longest path. The most critical path will be identical to the critical path that is derived when you select Define critical activities as: Longest Path on the General tab. In a multi-calendar project, the longest path is calculated by identifying the activities that have an early finish equal to the latest calculated early finish for the project and tracing all driving relationships for those activities back to the project start date. After the most critical path is identified, P6 will calculate the remaining sub-critical paths. 1
Choose an activity; typically the end of the project milestone or an interim finish milestone, that marks the end of a Phase or major event. Choose then number of paths to calculate. For example, if you choose 4, P6 will calculate the most critical activities and then the next 3 most critical paths based on the activity you selected. To display the bands, choose Group and Sort, Group by Float Path and Sort by Float Path Order. See example below:
Last but not least, it is always a good idea to view the log, after you have scheduled, to see a listing of valuable information. The log will show all the options that have been selected in the General and Advanced tabs, statistics on number of activities, activity status, relationships; error/warning log which include activities with no predecessors or successors; activities that are critical, and many other data points regarding you schedule. Many customers will use this log to analyze your schedule, so it always a good idea to not only view the log as you develop the schedule, but especially before it is ready for submittal to customer.
1 Oracle Primavera P6 Help – http://docs.oracle.com/cd/E68199_01/p6help/en/index.html