Activity Relationships | Primavera Scheduling - Official Site
For those not familiar with the Start to Finish or SF relationship type, the use of SF relationships, largely because few consumers of schedule. 4) Schedule dates for all of your sub-tasks using predecessors. To do this, I'll use Start-to-Finish predecessors in the sub-task rows. To create this type of dependency between rows, click on the predecessor cell for a sub-task and click the. Scheduling: Examining the Start to Finish Relationship. From time to ' Dependencies' (and activities/milestones) are what a CPM schedule sets out to model.
When you work with effort-driven scheduling, keep the following in mind: Tips and Gotchas Explanation Effort-driven does not apply to the first resource assigned The effort-driven calculations apply only after the first resources are initially assigned to the task.
After the first resources are assigned, the work value doesn't change as new resources are assigned to or removed from the same task. Be aware of Fixed-unit tasks If the assigned task type is Fixed Units, assigning additional resources shortens the duration of the task. Be aware of Fixed-duration tasks If the assigned task type is Fixed Duration, assigning additional resources decreases the individual unit values for resources. Be aware of Fixed-unit tasks If the assigned task type is Fixed Work, assigning additional resources shortens the duration of the task.
Some tasks can be set to effort-driven Summary tasks and inserted projects cannot be set to Effort driven. Top of Page How do manual and automatic scheduling affect the schedule? Knowing the differences between manually scheduled tasks and automatically scheduled tasks is key to understanding how Project schedules your project. Generally, manually scheduled tasks put you in control of the schedule.
When you add a task to your schedule, it stays put.
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Take a look at the picture below. It shows the two different types of tasks, the first two manually scheduled, and the last two automatic. Note that for the manually scheduled tasks, the duration is a text value as well as a number. Since the duration can be a text value, a start date hasn't been set automatically by Project, and the Gantt bar is only partially displayed to reflect the uncertainty of the task schedule at this point.
Max's Musings - Scheduling: Examining the Start to Finish Relationship
By definition, automatically-scheduled tasks with valid durations, start dates, and finish dates—and therefore, bars—are automatically drawn by Project. Now, it gets a little tricky sometimes with the information you provide for manually scheduled tasks.
All that is needed for Project to draw bars on a manually scheduled task are three time values: If you set two of these values for a manually scheduled task, the third value will be calculated by Project automatically, and the task will remain manually-scheduled. Tasks are manually scheduled by default.
Project managers who are accustomed to automatic scheduling with past versions of Project can turn the manual scheduling feature off for specific tasks or for the entire project.
Some projects, especially complicated ones, may require Project's powerful scheduling engine to take care of scheduling for you.
Start to Finish Relationships – to use them, or not?
To change all tasks to be automatically scheduled, click New Tasks: Automatically Schedule at the bottom of the Project application window. Manually scheduled tasks You can place a manually scheduled task anywhere in your schedule, and Project won't move it. This new feature gives you greater flexibility and control over planning and managing the schedule. Why would you care? Well, at times project schedules are often very informal.
How Project schedules tasks: Behind the scenes
They begin as simple lists of dates from e-mails, meeting with stakeholders, or a hallway conversation. Project managers very often do not have complete information on work items. For example, they may only be aware of when a task needs to be started, but not its duration until they have an estimate from their team members. Also, they may know how long a task will take, but they do not know it can be started until they have approval from the resource manager. Here are some things to keep in mind with manually scheduled tasks.
Standard types of dependencies[ edit ] There are four standard types of dependencies: The Practice Standard for Scheduling recommends, that "Typicallyeach predecessor activity would finish prior to the start of its successor activity or activities known as finish-to-start FS relationship.
Sometimes it is necessarily to overlap activities; an option may be selected to use start-to-start SSfinish-to-finish FF or start-to-finish SF relationships Whenever possible, the FS logical relationship should be used. If other types of relationships are used, they shall be used sparingly and with full understanding of how the relationships have been implemented in the scheduling software being used.
Ideally, the sequence of all activities will be defined in such a way that the start of every activity has a logical relationship from a predecessor and the finish of every activity has a logical relationship to a successor". Microsoft recommends to use SF dependency for just-in-time scheduling. These are the most important relationships in the schedule because they drive the start and finish dates of the activities that follow.
So it stands to reason that all critical path relationships are driving. In Primavera P6, driving relationships appear on the Gantt Chart as solid lines: Now, if every activity had only one predecessor we could ignore talking about the counterpart to driving relationships: After all, if there is only one person in front of you performing a task, how could they not be driving your work?
Well, there is one possible exception. Activity constraints can, in some situations, drive activity dates. For example, if the successor wants to start on August 3rd because the predecessor finishes the day before i.
Start to Finish Relationships - to use them, or not?
Finish-to-Start relationships make it easy to separate driving from non-driving relationships. If Activity C is waiting for both Activity A and Activity B to finish, whichever predecessor finishes last is the driving relationship. I am assuming that both relationships have zero lag, but it is considered bad form to use any lag other than zero days with Finish-to-Start relationships. Where it gets more interesting is when the predecessor relationships are Start-to-Start and Finish-to-Finish.
So here is my favorite example from our P6 class: The predecessor has a duration of 20 days The successor has a duration of 15 days There are two predecessor relationships coming from the same activity One of the predecessor relationships is Start-to-Start with a lag of 8 days The other predecessor relationship is Finish-to-Finish with a lag of 5 days Which predecessor relationship is driving?
Keep in mind there is only one predecessor activity, but there are two relationships. I will always add a Finish-to-Finish relationship to a Start-to-Start relationship. It is my insurance policy. I doubt that most Primavera users realize that if you only have a Start-to-Start relationship, the predecessor can finish on the last day of the project without causing a delay.