The Triple Constraint
By Jessica Popp
Ah, the triple constraint, the cornerstone of project management and project management (PM) lingo. Along the way, I will try to cover the most common acronyms and lingo that are used in the discipline. I neither intend to promote nor condone any particular use, or in many cases, overuse, of project management lingo. My goal is to create familiarity with the terms as they are commonly used in practice.
The triple constraint refers to the three inputs that govern the ability to deliver a project. The three commonly agreed upon constraints are budget, time, and scope. They are often drawn in a triangular shape to represent the relationship between them. This triangular arrangement helps to represent that any adjustment to one of these factors will have an impact on the other two. This relationship will become clearer with examples. Let’s start with definitions:
Budget – the allowed funds (money) that can be used to complete the project. This includes all sub-categories that which money can be spent to complete the project. The most common resources are materials and human capital. In construction, the budget might be constrained on physical building materials. In software engineering it is most often spent on human capital (i.e. software developers) and is generically referred to as resources. Many projects will have use a combination of physical materials and human resources.
Time – strictly speaking this is the amount of time needed to complete the work. This can be provided either as a deadline (time-constrained) or can be developed as a duration (calculated based on scope and available resources.) Very often in the corporate environment, the project manager is given a deadline by which the project needs to be delivered. In this common case, the project manager (PM) will work ‘backwards’ from the deadline to complete the project, which is often troublesome for many reasons which will be explained in later posts.
Scope – this is merely what needs to be delivered. Alternatively this can be described as scope of work, the deliverable,a product or requirements. The final project can deliver something tangible such as a building, computer software or designs to build a new line of clothing. Or, at the completion of the project completion there may be something intangible such as new processes for patient protocol in a doctor’s office.
In its simplest form, these three factors govern all that the project manager does. Through the relationships of budget, timeline and scope the project will be executed. The finesse and skill of the project manager to properly manage the relationship inherit to the triple constraint will greatly influence the outcome of the project.
Jessica Popp is a practicing project manager in software engineering. She has more than 13 years experience in software development, project management and people leadership in both Fortune 500 and startup companies. She has a wealth of hands-on project experience from the smallest project to projects whose budgets exceeded $50M per year. Jessica holds a BBS in Information Systems, an MS in Decision Sciences and has a current PMP certification. Jessica runs Project Management 101, a blog dedicated to disccussing various topics about Project Management.