Understand the Iron Triangle in Project Management

The Sydney Opera House is an architectural masterpiece, but its delayed completion was characterised by poor project management. In its design, project managers severely underestimated its cost and execution, and didn’t factor in the impact that changes to the scope would have on the budget and timeframe. The cultural landmark is a prime example of the interdependent relationship between these three important elements: cost, time, and scope.

Watch Kyle de Freitas, Head Tutor on the University of Cape Town (UCT) Project Management Foundations online short course, talk about the importance of setting realistic and achievable project objectives.

Transcript

The Sydney Opera House, an icon of 20th century architecture. Majestic, inspiring – and a complete project failure. Wait. What? Yes, you heard me correctly. The Sydney Opera House was originally estimated to cost seven million dollars and take four years to complete. Instead, it cost 102 million dollars and took 14 years to complete. That’s 14-and-half times more expensive and 10 years late on delivery. But, as a product, it has been a huge success. How did this happen?

To understand this, let’s take a look at a concept called the triple constraint, also known as the iron triangle. This triangle aims to illustrate the interdependent relationship that exists between the elements of cost, time, and scope.

What happens when we make adjustments to each element within the triple constraint? For example, if we shorten or lengthen the schedule, what impact would this change have on cost and scope? If we are working on a project that has already passed through the detailed planning phase, and new user requirements are identified, which were not included in the original project plan, then these additional requirements would represent an increase in scope if approved.

In order to ensure that our project constraints remain balanced, cost and time will most likely have to increase in order to absorb the additional scope. If the project’s deliverable is required by an earlier date, in other words, earlier than originally planned, while still meeting all the remaining project objectives, then we need to crash the project schedule.

Crashing the project schedule requires additional resources to be allocated to the project. The additional resources will add to the cost of the project, hence the budget will have to be revised accordingly. Alternatively, if there is a delay during the project caused by an unforeseen resource shortage, then any corrective action taken to put the project back on track will ultimately result in an increase in project costs.

We can conclude that these three elements are dynamic and their effect on one another will vary depending on the nature of the project.

A fourth constraint can be added to the triple constraint: quality. This additional constraint leads us towards the development of the quadruple constraint. On many projects, cost and time are prioritized over scope and quality. This is where corners get cut in the interest of preserving the budget and schedule.

At the end of the day, the project objectives set must be realistic and achievable in order to ensure that a successful project is probable.

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