Add a Constraint to an Activity

Constraints are used to impose external restrictions on project activities. They are used in the scheduling process when calculating activity start and finish dates. You can use constraints for situations where activity relationships are not adequate to provide the logic necessary to properly schedule an activity. Constraints can also be used for an activity without a natural predecessor or successor.

You can add up to two constraints to an activity — a primary constraint and a secondary constraint. After a primary constraint is set on an activity, it determines the list of available secondary constraints that you can set on the activity.

Note: You cannot set a secondary constraint on an activity if the primary constraint is Start On, Finish On, Mandatory Start, or Mandatory Finish.

To add constraints to an activity:

  1. Navigate to the Activities page
  2. In the table, select the activity.
  3. On the Layout menu, select Activity Details, and then select the Status detail window.
  4. In the Primary Constraint list, select a primary constraint:
    • Start On: Imposes the specific start date you select. The Start On constraint can delay an activity's early start or move forward an activity's late start to satisfy the constraint date.
    • Start On or Before: Defines the latest date an activity can start. This constraint only affects late dates and can decrease total float. When calculating a schedule, the application imposes the start on or before constraint in the backward pass only if the calculated late start date will be later than the imposed date.
    • Start On or After: Defines the earliest date an activity can begin. This constraint affects only early dates. When calculating a schedule, the application imposes the start on or after constraint in the forward pass only if the calculated early start date will be earlier than the imposed date.
    • Finish On: Imposes the specific finish date you select. The Finish On constraint can delay an activity's early finish or move forward an activity's late finish to satisfy the constraint date.
    • Finish On or Before: Defines the latest time an activity can finish. The finish on or before constraint affects only late dates.
    • Finish On or After: Defines the earliest date an activity can finish. The finish on or after constraint reduces float to coordinate parallel activities, ensuring that the finish of an activity is not scheduled before the specified date. It is usually applied to activities with few predecessors that must finish before the next phase of a project.
    • As Late As Possible: Imposes a restriction on an activity with positive float to enable it to start as late as possible without delaying its successors. When calculating a schedule, the application sets the activity's early dates as late as possible without affecting successor activities. This option disables the calendar icon.
    • Mandatory Start: Imposes the early and late start dates you select. A mandatory early start date could affect the late dates for all activities that lead to the constrained activity and all early dates for the activities that lead from the constrained activity.
    • Mandatory Finish: Imposes the early and late finish dates you select. This constraint affects the late dates for all activities that lead to the constrained activity and all early dates for the activities that lead from the constrained activity.
  5. In the Primary Constraint Date field, enter a date for the primary constraint.
  6. If your primary constraint selection allows for a secondary constraint, do the following to set a secondary constraint:
    1. In the Secondary Constraint list, select a secondary constraint.
    2. In the Secondary Constraint Date field, enter a date for the secondary constraint.
  7. All changes made to this page are saved automatically.

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Last Published Tuesday, May 21, 2024