Finish-to-Finish (FF) Dependency
A Finish-to-Finish (FF) dependency is a logical relationship in which a successor activity cannot finish until a predecessor activity has finished.
Explanation
Finish-to-Finish dependencies link the completion of two activities together. The successor activity can start independently, but it cannot be marked as complete until the predecessor has also been completed. This is useful when two parallel activities must end at roughly the same time or when the completion of one activity depends on data or deliverables from the completion of another.
For example, writing a document (predecessor) and editing that document (successor) might have an FF relationship. Editing cannot finish until writing finishes because the editors need the final written content before they can complete their review. The editing may have started earlier, but its completion depends on the writing being done.
FF dependencies are often paired with SS dependencies to create a fully constrained pair of parallel activities. Together, SS and FF relationships ensure that two activities start in a controlled sequence and also finish in a controlled sequence. Lags can be applied to FF relationships to introduce a delay between the finish of the predecessor and the allowed finish of the successor.
Key Points
- •Successor cannot finish until predecessor finishes
- •Activities can run in parallel but must finish in sequence
- •Often paired with SS dependencies for fully constrained parallel work
- •Lags can offset the finish times between activities
Exam Tip
FF does not mean both activities finish at the same time. It means the successor is not allowed to finish until after the predecessor finishes.
Frequently Asked Questions
Related Topics
Precedence Diagramming Method (PDM)
The Precedence Diagramming Method (PDM) is a technique used to construct a schedule model in which activities are represented by nodes and are graphically linked by logical relationships to show the sequence of activities.
Start-to-Start (SS) Dependency
A Start-to-Start (SS) dependency is a logical relationship in which a successor activity cannot start until a predecessor activity has started.
Finish-to-Start (FS) Dependency
A Finish-to-Start (FS) dependency is a logical relationship in which a successor activity cannot start until a predecessor activity has finished.
Leads and Lags
A lead is the amount of time a successor activity can be advanced with respect to a predecessor activity. A lag is the amount of time a successor activity must be delayed with respect to a predecessor activity.
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