Strategy, PM, and the Triple Constraint of a Project

The Triple Constraint, or Iron Triangle, is a great tool for implementation. It applies well in practice especially to project management – but also is useful in the practice of strategy. While it originated in project management lexicon, it has strong applicability in the two-way dialog between strategists and project managers.

What Is the Triple Constraint of a Project?

triple constraint of a project

The Triple Constraint of a project, sometimes referred to as the Iron Triangle, elegantly and practically explains the relationship among three constraints: scope, time, and cost – and how they must adjust to deliver a product of fixed quality.

These three are universal constraints on any and all projects, and they all affect quality.

  • Scope – the limits of the requirements for the projects
  • Cost – the budget for the project
  • Time – the duration planned for the project

Quality is the combination of all attributes that form the standard expectations for the product of the project.

To illustrate, let’s look at how each of these relate to each other.

  • Scope to Time – An increased scope will take more time, while a decreased scope will take less time.
  • Scope to Cost – An increased scope costs more, while a decreased scope costs less.
  • Time to Cost – If the schedule tightens and less time is allowed to complete the project, cost will increase. Likewise, cost will decrease if the schedule is loosened, giving the project more time to complete.

Certainly there are nuances to these, but the constraints hold universally.

Now let’s turn to how each of these relates to Quality:

  • Scope to Quality – Increasing the scope can lead to dilution of quality, while decreasing the scope can lead to a higher level of quality.
  • Time to Quality – More time helps to shake out quality issues, while with less time, quality can suffer.
  • Cost to Quality – A higher cost allowance supports higher quality, while a lower cost allowance can have a negative effect on quality.

The above illustrate relationships between each of the variables. The real magic of the Triple Constraint, however, is in how all three of the constraints work together. Assuming you want to reach a fixed level of quality, here’s how the constraints would work:

  • Increased scope – To maintain quality, cost and/or time will need to increase.
  • Decreased time – To maintain quality, some combination of decreased scope and increased cost must be accomplished.
  • Decreased cost – To maintain quality, a decreased scope and/or increased time will be required.

The Triple Constraint is known as the Iron Triangle because there are immutable tradeoffs among the three constraints in order to deliver the same quality output. A change to one leg of a triangle cannot occur without corresponding changes to the other legs.

Use of the Triple Constraint in Practice

When under pressure from stakeholders to deliver more with less – a common project management challenge – the Triple Constraint can be a very useful tool!

Let’s say that your customer is asking for an expanded scope. Using the Triple Constraint, you can bring the tradeoff to them: you can deliver, if they are willing to increase the cost and/or time for the project.

Alternatively, your customer asks you to deliver for a lower cost. Using the Triple Constraint, you can respond with confidence that this can only be achieved if you are given more time and/or the scope is decreased.

In another situation, your customer may ask that the delivery be made sooner – in less time. Using the Triple Constraint, you can respond that it is possible to deliver in less time if scope is decreased and/or cost is increased.

The power of the Triple Constraint is that it gives you a workable response in the face of such inevitable requests. It tends to help keep the project under control, and helps control the need for heroics to do the impossible.

Strategy and the Triple Constraint

In evaluating choices in the process of developing strategy, it seems wise to consider the Triple Constraint.

Certainly, each choice considered needs to be evaluated for whether it is possible. That evaluation needs to consider, based on the quality attributes needed, how scope, cost, and time can be adjusted to achieve the result.

Strategy itself is driven by constraints. That’s why it is about choices. In thinking strategically, it is always helpful to look through the lens of constraints, as it leads more directly to making better 80:20 choices all along the way.

Many – maybe all – of the strategic choices relate to the Triple Constraint:

  • Scope – What is the range, or the limits, of the strategic business venture being considered? What are the limits to the initiatives for the strategy?
  • Cost – What is the expectation of the cost to implement a strategic choice?
  • Time – What is the timeframe for the launch of the strategic initiative?

Doing some high level project planning, as well as part of a sanity check – an assessment of the viability of the strategy in practice is a good use for the Triple Constraint.

Project Management and the Triple Constraint

Personally, I have found the Triple Constraint to be a powerful tool, especially against scope creep and schedule pressure by clients. But the concept can also provide a solid reality check across the range of project management functions. Here’s how.

Method123 PM templates

  • Program Management – A program can check if it is truly grounded by testing assumptions on objectives against the variables of scope, time, and cost. Furthermore, doing so can force the discussion on the level of quality needed, as that can lead to more favorable planning in terms of scope, time, and cost. Finally, projects can be sized or scoped to optimize the variables of the Triple Constraint.
  • Portfolio Management – One of the goals is to get the most done with the resources at hand. That’s an exercise in managing with constraints. The Triple Constraint can help with that evaluation at a lower level of detail, acknowledging that the key scarce resources are time and cost, where scope and quality can be adjusted to optimize,
  • Project Management – The intent of the Triple Constraint is to enable project managers to grapple more effectively with scarce resources. It grounds the project in reality and helps deflect challenges that could easily derail an otherwise good project.

The Triple Constraint originated from the project management world and is a foundational tool for implementing effectively.

Put the Project Triple Constraint Into Practice

The following are resources for working through practical problems of strategy and project management – and where you can apply the Triple Constraint.

4 thoughts on “Strategy, PM, and the Triple Constraint of a Project”

  1. When we are creating the blueprint of a project, it is impossible to arbitrarily set all these variables. In addition, we need to understand how these project components are interrelated to develop a realistic and achievable plan.

    Something that happened to us a lot during COVID-19 was that a component of the triple constraint changed. Then I had to assess the impact on the rest of the variables. Having a clear understanding of this gave me a workable response in the face of the inevitable requests.

    • Thank you for your points, Paolo.  I agree, it is impossible to arbitrarily – or precisely – set all these variables.  But it depends on the situation.  More and more projects today are done with an agile approach because of this – because things are less predictable.  Also, I am glad to hear of your experience during COVID – that using the triple constraint was able to hep give you a practical perspective for responding effectively.

  2. This is a good strategic planning tool although more relevant to Project Management. Is this another of Michael Porter’s tools? I totally agree with the concept but would like clarity on ‘If the schedule tightens and less time is allowed to complete the project, the cost will increase’, why would cost increase if the project schedule tightens? Likewise, costs will decrease if the schedule is loosened, giving the project more time to complete. How will cost decrease if the project schedule is increased?

    I’m glad I came across your blog. I definitely will be revisiting to learn more about project management.

    • Thank you Kavinah for your comment!  Good questions – let me try and answer.  If the schedule tightens (less time), you will probably need to put more people and other resources on the project to complete it at the same level.  Likewise, if your schedule loosens, you will probably be able to use fewer resources to get the work done in the longer time period.  In these cases, the overall cost may still be the same – it depends – but in the short term or on a monthly or weekly basis, the costs will go up or down.

      Thanks again!  Hope that helps!


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