The Demise of the Iron Triangle

The iron triangle was invented by Dr Martin Barnes in 1969 to demonstrate the connection between time, cost and output (correct scope at the correct quality) – see The Origins of Modern Project Management. The correlation remains but the concept of the triangle is fading and becoming more complex.

The problem with the triangle is whilst the three interconnections are relevant; the way the elements interact geometrically is not intuitive or correct. Output should react inversely to the other two dimensions. Less output is bad, but less time or cost is potentially good.

As we move into second decade of the 21st century, leaving the ‘noughties’ behind, PMI have dropped the concept of the iron triangle from the PMBOK® Guide and the search is on for more meaningful and unfortunately complex metaphors to define the challenges of satisfying a project’s stakeholders and customers. This is a multi-dimensional problem and there is a real need for a new paradigm similar to the iron triangle but representing the many different facets of success.

As Albert Einstein once said “For every complex question there is a simple and wrong solution.” And whilst the iron triangle was not intrinsically ‘wrong’ in the 70s, 80’s and possibly 90’s it is certainly incomplete in the complex world of the 2010s.

I have seen several attempts to replace the simplicity of the triangle with tetrahedrons and multi dimensional effort charts but they lack clarity of insight. Another quote from Einstein is “If you can’t explain it simply, you don’t understand it well enough.” The question and challenge is how to replace a project management icon as powerful as the ‘iron triangle’ with a more representative symbol.

What will be the new symbol of project management in the ‘teen years for the 21st century? Any ideas are welcome.

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4 responses to “The Demise of the Iron Triangle

  1. Pat,

    The “Triangle” now in use in Aerospace and Defense is Paul Solomon’s Cost, Schedule, and Technical Performance. The Technical Performance Measures were pioneered by then Cmdr Nick Pisano, now President of Safran NA.

    The “triangle” describes the three dependents variables.

    This is a 3 body problem from classical physics is a similar mode, whose solution to three equations and at least three unknowns is solved by Monte Carlo simulation – which is now mandated through DID 81650.

    So the triangle is here, but it’s not your fathers triangle.

  2. Cost, Schedule, and Technical Performance or Time, Cost, Output are important tools when explaining the basics to non project people.

    Not every organsaition is mature in project processes and in many instances people still need the trade-offs explained in simple concepts. It’s a shae the triangle is losing favur as it is a usefuyl tool.

  3. I am almost brand new to blogging and really like your post, it is really on target!

  4. Pingback: Passing the #PMP Exam—Study Group Discussions (Chapter 1—Constraints on a Project) « 4squareviews

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