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The triple restriction or the "iron triangle" in project management

What does the triple restriction refer to in project management?

In the modern business landscape, different variables must be taken into consideration to achieve a successful execution of projects. However, since the birth of project management as a discipline, 3 main restrictions with the greatest impact have been identified. The Triple Constraint, also called the "Iron Triangle" in project management, defines these three factors (and their variations) as follows:

  • Scope, time, budget

  • Deliverables, schedule, cost

  • Good, fast, cheap

While the names of the three items may change, they all measure essentially the same thing: a set budget, an estimated timeline or timelines, and a fixed set of expectations or deliverables.

Why is it known as a triangle?

The triangle is the most stable geometric shape. In addition to showing the relationship between the project objectives, the time it will take to produce them and how much it will cost to complete the work, it emphasizes that any attempt to make changes to a corner will have an immediate impact on the other two.

For example, if a customer requests an earlier delivery date, the project is likely to need more resources or perhaps a scope reduction. The same happens in case of requiring greater scope or functionality, since it will inevitably take more time to do it and it will cost more. Finally, if the client restricts the budget, they will have to accept a smaller quantity of deliverables.

What are the different variations of the iron triangle?

Some project managers find that the triangle is not detailed enough to capture all the variables that affect the execution of a project. Therefore, another factor that is commonly introduced to complement the revised triangle is the concept of quality. However, there are different points of view on this, since quality is subjective. For example, will the overall quality of the work performed be affected? Or, can it still be high-quality work with a narrow scope? These are the questions a project manager should always keep in mind during conversations with stakeholders, sponsors, and clients.

Other experts, including the PMBOK ("Project Management Body of Knowledge") - the guide of fundamentals for project management - speak of balancing competing constraints within the project and include, but are not limited to: scope, quality, time, cost, resources, and risks. Also, it is sometimes recommended to use a six-pointed star, which includes these components that are important, but perhaps too subjective to measure as a pillar of constraint.

What benefits does the consideration of the triple restriction bring?

The principles of the triple constraint and how they affect a project or program have to be established early in their life cycle, as all projects have different degrees of sensitivity to changes in one of the three main constraints. It is a project manager to be proactive in defining constraints, rather than reactive when something suddenly changes. Additionally, being clear about the concepts and understanding of their relationship provides transparency and helps to identify possible causes of scope variation and alternatives to address problems.

Enforcing the “iron triangle” is one of the key responsibilities of the project manager and for that he / she needs, among other things, to develop a schedule and a resource plan to achieve the success of the project, as well as to keep a detailed change control . Undoubtedly, in this process it is essential to have the support of specialized project management software. Get to know the technological solutions we have for you on our page!

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