Last updated on February 2, 2016
PDM Relationships – Start to Finish
This article extends my previous article on Project Network Diagram. Project Network Diagrams are used to pictorially represent Project Schedule and Project Dependencies. You can also read my other articles on Project Dependencies – What are Project Dependencies and 4 Types of Project Dependencies.
There are many ways to draw a Project Network Diagram. One of them is Precedence Diagramming Method (PDM). PDM defines 4 Logical Relationships to represent Project Dependencies. This post to describes Start to Finish (SF) Relationship. Start to Finish is one of the 4 Logical Relationships. The other 3 Logical Relationships are Finish to Start, Start to Start and Finish to Finish.
Definition of Start to Finish Relationship
It is a Logical Relationship in which a Successor Activity cannot finish until a Predecessor Activity has started. In other words, the Finish of a Successor is Dependent on Start of the Predecessor.
The most common and most natural relationship is Finish to Start (FS). Start to Finish Relationship is very rarely used. The Project Managers have some flexibility while defining the relationship between 2 activities. Usually it is possible for them to transform a SF Relationship to a FS Relationship.
You can also look at Max Wideman’s Glossary for complete set of definitions on PDM Logical Relationships.
Project Network Diagram Representation
Let us consider two activities A and B.
The Project Team will need a total of 4 days to complete these activities.
Bar Chart Representation
B can Finish (F) only after A Starts (S)
B(S) = A(F)
Let us consider 2 activities A and B. Let us also consider A to be the Predecessor and B to be the Successor.