The three major constraints on any project are always going to be time, budget, and quality. All project managers have to deal with these constraints in all projects. No project manager I know has ever been given unlimited funding and unlimited time to produce a perfect product. It just doesn't happen that way - not if you want to stay in business for very long. In reality, if we were given unlimited funding and unlimited time, some of us probably wouldn't accomplish much. This is especially true for all of you out there who are the perfectionist types. Just tweak this and then tweak that, soon it will be perfect next iteration. Given unlimited time to perfect means that it will never truly be finished!
Defining project constraints
Project constraints are anything that either restricts the actions of the project team or dictates the actions of the project team. Constraints put you in a box. As a project manager, you have to manage to the project constraints, which sometimes requires creativity. Like most disciplines, project management can often be as much art as it is science. As much creative as it is process-driven.
Time as a constraint
As mentioned above, time can be a project constraint. This usually comes in the form of an enforced deadline, commonly known as the 'make it happen now” scenario. If you are in charge of the company's holiday bash scheduled for December 10, your project is time constrained. Once the invitations are out and the hall has been rented, you can't move the date. You can't just go into your software such as Seavus Project Viewer and move the tasks further out. It's set in stone now - all activities on this project are driven by the due date.
Budget as a constraint
Budgets are another one of the triple constraints. Budgets limit the project team's ability to obtain resources and might potentially limit the scope of the project. For example, component X cannot be part of this project because the budget doesn't support it.
Quality as a constraint
Quality would typically be restricted by the specifications of the product or service. Most of the time, if the quality is a constraint, one of the other constraints - time or budget - has to have some give. You can't produce high quality on a restricted budget and within a tightly restricted time schedule. Of course, there are exceptions, but usually not in reality - just in the movies.
Schedule constraints can cause interesting dilemmas for the project manager. For example, say you're the project manager in charge of building a new football stadium in your city. The construction of the stadium will require the use of cranes - and crane operators - at certain times during the project. If crane operators are not available when your project plan calls for them, you'll have to make schedule adjustments so that the crane operators can come in at the right time.
Technology is a marvelous thing. In fact, how did humans survive prior to the invention of computers and cell phones? Technology certainly can be marvelous, but it can also be a major project constraint. For example, your project might require the use of leading-edge technology that is still so new it's not been released on a wide-scale basis. One impact might be that the project will take an additional six months because existing technologies need to be used instead of the new technology. Directives from management can be constraints as well. If you've never experienced a directive from management, you're not working in the real world. And, when performing work on contract, the provisions of the contract can be constraints.