Project Management: Constraints Management in Planning

In a project, the planning of tasks, with associated estimates, resources, assignments and dependencies, can require a good amount of critical thinking. Introducing constraints adds even more thought, and can increase the maintenance of the project schedule.

There are many types of constraints, with varying degrees of flexibilities. In a project, many tasks can start ASAP (As Soon As Possible). For example, after cement has been poured for the base of a house, and has dried, then the wood framing construction can begin As Soon As Possible.

There may be an instance when, because of timing, tasks may start As Late As Possible. For example, back to the construction of the house, carpet may be installed as Late As Possible because the owner does not want anyone walking on it before the owner actually moves in.

There are other constraints such as Start No Earlier Than (SNET), Finish No Earlier Than (FNET), Start No Later Than (SNLT), and Finish No Later Than (FNLT), Must Start On (MSO), and Must Finish On (MFO). Packages such as Microsoft’s Project, provides these constraints for enhanced flexibility.

Many prefer to minimize the amount of constraints in a project since they require additional attention. Having Task B start As Soon As Possible, following Task A, is visually easy to see. If Task B has a constraint of Start No Earlier Than (SNET), it involves another dimension, time, on top of a dependency, which requires explanation.

Limiting the project schedule to simpler dependencies with as little number of constraints as possible, can make reporting, and managing the project easier for the project manager. With multiple concurrent projects, the discipline of constraints management can save quite a bit of schedule maintenance.