ADDING 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|
||Drag the mouse pointer from one activity to another to create a dependency.|
||Predecessor and Successors may be added and deleted from the Relationships, Predecessor or Successor tabs.|
||Double-click an activity link in the Bar Chart or PERT View.|
|Double-clicking in the Predecessor or Successor cells will open the Assign Predecessor form and the Assign Successor form.|
||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.