After determining the connections between the project’s tasks, we must also determine the constraints affecting the project’s tasks. The process of identifying constraints to the project’s main stages and tasks was done partially in the preliminary planning stage. We must now go through the same process for the tasks detailed in the project’s work plan.
Differentiation must be made between two separate elements: a connection between tasks and a constraint on a task.
When a task depends on another task within the project’s framework, then we create a connection between the two tasks. However, when a task depends on another task that is outside the project’s scope or work plan, then we say that the first task is constrained by the second task.
Time constraints belong to one of three groups:
“Flexible” constraints group:
“Rigid” constraints group:
“Semi-flexible” constraints group:
- “Flexible” constraints group – Does not refer to a specific date but just to the need to execute a task as early or as late as possible.
- “Rigid” constraints group – Refers to a specific date on which the task must either begin or end—not before and not after, respectively. Constraints in this group limit the overall flexibility of the work plan so efforts should be made to verify whether the constraint does indeed belong to this group or whether it belongs to the third, far more common group.
- “Semi-flexible” constraints group – refers to an earlier or later limit on which a task must begin or end. That is, the task must begin not before or not after a certain date, or must finish not before or not after a certain date. For example, a constraint of finishing not after a certain date does not mean the task cannot be finished well before that date.
For example: The project-planning task depends on the approval of next year’s budget, which is not managed within the project’s work plan. Therefore, this task has a “start no earlier than” constraint; it cannot be started before the date on which the annual budget is expected to be passed.
Ensure that all of the known constraints on the project have been identified, defined and linked to the appropriate tasks, so that the work plan reflects reality. At the same time, it is best to try to minimize the number of constraints affecting the project in order to preserve maximum flexibility.