A dependent activity that logically comes after another activity in a schedule.
Project Management Institute, A Guide to the Project Management Body of Knowledge (PMBOK® GUIDE) – Sixth Edition, Project Management Institute, Inc., 2017
What is Predecessor and Successor?
A predecessor is an activity whose start or finish controls start or finish of another activity. And a successor is an activity whose start or finish is controlled by start or finish of another activity. In process of determining relationships between activities, predecessor and successor activities are identified first and then they are given a relationship type, for example Finish to Start.
The Concept of Predecessor and Successor:
The concept of predecessor and successor is important to understand. Let us see an example. In the diagram below, there are two activities A and B. Both are linked to each other. Note the originating point of arrow. Arrow is starting from finish of activity A and its ending at start of activity B. Or you can say that start of B is being controlled by finish of A. So A is the predecessor and B is the successor activity and type of relationship between these two activities is Finish to Start. While linking these activities, first step would be to identify predecessor and successor/s. Or you can say which activity is controlling and which activity or activities it controls. Then the relationship type between these activities would be determined, for example finish of activity A controls start of activity B or Finish to Start.
It is often considered that an activity which comes first in schedule is predecessor and activity which comes later is a successor activity, however this is a wrong concept. For example, see the diagram below. Note that both activities have same start. As arrow is originating from start of activity A, this means activity A is a predecessor and its ending in start of activity B so activity B is a successor. This type of relationship is called Start to Start or SS relationship.
Now lets us see another example. In the diagram below, finish of activity B is being controlled by start of activity A. Can you guess the predecessor and successor activity in this case? This type of relationship is called Start to Finish or SF relationship.
So, if you have guessed activity A as the predecessor and activity B as the successor then congratulations, you have understood the concept of predecessor and successor.
Read Also: Types of Relationships in Primavera P6
A Successor is an activity relation and dependency in a network sequence schedule. The Successor activity (follower) comes after a particular activity (basis) in a continuity to complete task or work.
Related Definitions in the Project: The Project Schedule
In project management a successor is an activity that follows another activity – not in the chronological sense but according to their dependency to each other. A successor activity can have several direct predecessor activities.
To determine the direct predecessors of an activity, you must clarify which activities you must complete before you can start the activity you’re currently looking at (reasons can be technical, organizational or methodological in nature).
To determine the direct successors, you must clarify which activities can only begin after you completed the current activity (reasons can be technical, organizational or methodological in nature).
Successors usually follow their predecessors in a chronological order, but there are some (very few) cases where the successor starts before its predecessor (start-to-end – see dependencies). This is a rare case however and it’s often hard to comprehend as it goes against our notion of time.
- Predecessor
- Dependencies
- Scheduling
- Gantt chart
- Buffer
Project management must keep the various activities of a job in mind when they are creating a plan or conveying steps in a procedure. A successor activity is the descriptor to define a task which occurs following a predecessor activity. Order is very important in business. Should an employee not understand the order being communicated by those in project management, the overall result of the task could suffer. Employees need to be told by management the correct list of predecessor and successor activities.
To ensure that employees understand the order of steps required, those in project management frequently use charts and maps to illustrate their points. The steps should follow in a logical order. Even if the activities are not labeled as successor or predecessor their placement in the flow chart or map should be obvious. Successor activities will always come after predecessor tasks. Even if the employees are not aware of the proper titles for the activities, those in project management must know them so that they can create accurate and easy to read flow charts and maps for the project.
This term is defined in the 3rd and the 4th edition of the PMBOK.