Project Planning and Control Using Oracle Primavera P6 - Version 8.2 EPPM WebADDING RELATIONSHIPS IN PRIMAVERA P6

The next phase of a schedule is to add logic to the activities. There are two types of logic:

  • Relationships (Dependencies or Logic or Links between activities), and
  • Imposed Constraints to activity start or finish dates. These are covered in the Constraints chapter.

The Primavera Help file and other text use the terms Relationships and Logic for Relationships but do not use the terms Dependencies or Links.

We will look at the following techniques in this chapter:

Topic Notes for creating a SF Relationship
  • Graphically in the Bar Chart.
Drag the  mouse pointer from one activity to another to create a dependency.
  • By opening the Activity Details form.
Predecessor and Successors may be added and deleted from the Relationships, Predecessor or Successor tabs.
  • By editing or deleting a dependency using the Edit Relationship form.
Double-click an activity link in the Bar Chart or PERT View.
  • Opening the Assign Predecessor form or the Assign Successor form from the menu.
  • Select Edit, Assign, Predecessors…, or
  • Select Edit, Assign, Successors….
  • By displaying the Predecessor and/or Successor columns.
Double-clicking in the Predecessor or Successor cells will open the Assign Predecessor form and the Assign Successor form.
  • Chain Linking or Automatically Linking activities with a Finish-to-Start relationship.
Select the activities in the order they are to be linked using the Ctl key, right-click and select Link Activities.


There are two types of dependencies that are discussed in scheduling:

  • Hard Logic, also referred to as Mandatory or Primary Logic, are dependencies that may not be avoided: for example, a footing excavation has to be prepared before concrete may be poured into it.
  • Soft Logic, also referred to as Sequencing Logic, Discretionary Logic, Preferred Logic, or Secondary Logic, ,may often be changed at a later date to reflect planning changes: for example, determining in which order the footing holes may be dug.

There is no simple method of documenting which is hard logic and which is soft logic as notes may not be attached to relationships. A schedule with a large amount of soft logic has the potential of becoming very difficult to maintain when the plan is changed. As a project progresses, soft logic converts to hard logic due to commitments and commencing activities.

Microsoft Project allows one relationship between two activities, SureTrak and P3 two relationships between two activities and P6 four relationships between two activities.

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