Start to Finish Relationship in Project Management
In this article, I have defined and explained Start To Finish Logical Relationship with the help of Project Network Diagrams, Gantt Charts & Examples. Start to Finish (SF) is one of the four relationships described in Precedence Diagramming Method (PDM).
The other three are:
These are used to represent and analyze project schedule. This concept originated with PDM. However, by using modern scheduling tools like MS Project and Primavera, you can pictorially represent them on Gantt Charts as well. These relationships are sometimes referred to as project dependencies but former is a better term.
Definition of Start to Finish Relationship
Start To Finish is a Logical Relationship in which a Successor Activity cannot finish until a Predecessor Activity has started.
In simple words we can say that, the Finish of a Successor Activity is Dependent on Start of the Predecessor Activity.
The most common and natural relationship is Finish to Start (FS). Some authors (incorrectly) claim that FS and SF are essentially same. However, it is not true. Even though it is mathematically possible to transform SF to FS to achieve the same result, one should not modify and tamper with natural logic. In real world, SF is very rarely used. You can read FS vs. SF for more details.
You can also look at Max Wideman’s Glossary for a complete set of definitions on PDM.
Project Network Diagram Representation
Let us consider two activities A and B.
- Duration of A – 3 days
- Duration of B – 1 day
- B has a SF relationship with A
- B’s Finish is dependent on A’s Start – B can Finish (F) as soon as A Starts (S).
In the above example, the Project Team would need a total of 4 days to complete these activities.
Gantt Chart Representation
Mathematical Representation And Formulas
If you are using 0 method
B(F) = A(S)
Or, if you are using 1 method
B(F) = A(S) – 1
Start To Finish Examples
- A – Duty of Evening Guard (E), B – Duty of Morning Guard (M). M cannot Finish her/his duty till E Starts. M cannot abandon the post.
- A – Start using New Software System (N), B – Phase out Old Software System (O). It is assumed that N & O cannot be used in parallel.
Over To You
SF is not a very difficult concept to understand. But sometimes it is confused with FS. After reading this article, do you still have a question(s)?
Do you think this is useful in real projects? Have you ever used it in you project(s)?
Please leave a comment.
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