Constraints

Constraints are limitations that you set on tasks. For example, you can specify that a task must start on a particular date or finish no later than a particular date. In RiskyProject, you can assign one of four constraints to a task:

• As Soon As Possible (default)
• Start No Earlier Than
• Must Start On
• Must Finish On
• Finish no Earlier Than
• Finish no Later Than

Summary tasks have only “As soon as possible” and “Start no earlier than”.

Use the General tab of Task Information dialog box to add or modify constraints. If you set a constraint to Start Not Early Than, an additional edit box opens in which you set the date for this constraint.

If you assign a constraint other than As Soon As Possible, the background color for low, base, and high Start Times or low, base and high Finish Times changes to orange and the icon next to the task name has a red dot added to indicate that the constraint is other than As Soon As Possible.

Use constraints to ensure that that the task starts or finishes on the specific dates. Use caution when you link tasks with a constrained start or finish time with predecessors because of the potential for scheduling conflicts. In this situation, to avoid scheduling conflicts, set the constraint to As Soon As Possible.
Constraints affect both probabilistic and deterministic calculations. If you change the Low or High Start times, the constraint is set to Must Start On, similar to when you change the Base Start time.

When a task has a constraint other than As Soon as Possible, it may not shift due to the nature of Monte Carlo calculations, even if predecessors have risks and uncertainties. Therefore, use caution when planning to perform probabilistic calculations with constraints.
When you enter the actual start date of the task as part of tracking input, task would become constrained for the probabilistic calculation only. Start time will not change regardless of risks and uncertainties for predecessors.

See also

Adding constraints