The Iron Triangle of Successful Project Management

Maintaining Balance of the Triple Constraints to Maintain Project Quality

Ever heard of the Iron triangle? Also known as the triple constraints, flexibility matrix, or project triangle, the Iron Triangle is one of the most important concepts in project management.

There are three constraints in all projects

All projects, irrespective of size and complexity, have three constraints:

·       Scope

What tasks must be completed to deliver the project’s goals?

This is the scope of the project, and scope creep is almost guaranteed to increase project costs. A simple example is if a client changes project deliverables and this requires two days extra work, then cost of labour will increase.

Project scope should be identified early in the project process.

·       Time

When should the project be completed?

It’s crucial to know when the project is expected to be completed. This will determine when tasks must be done, and is related to project scope. Without identifying scope and the tasks involved, it is impossible to set a realistic goal for the project to be completed.

As well as being linked to project scope, time is linked to project cost. If a project is to be completed faster, then costs are likely to rise.

·       Cost

What is the budget for the project?

No project should be initiated without an assessment of how much money it will cost to deliver.

The project’s budget will impact both scope and time. For example, if the client reduces the amount of money available for the project, then this might mean that fewer tasks can be completed, or that more resource must be made available to complete the project in the shortened timeframe.

Put the constraints together, and you have the Iron Triangle

The Iron Triangle was formulated by Dr Martin Barnes in 1969. It describes how the triple constraints interact and impact each other. A project manager has their work cut out to keep the triangle balanced.

Most crucially, the balance of scope, time, and cost will determine the quality of the completed project. If any of the three are redefined, there will need to be negotiation of the other two. A trade-off is inevitable.

For example, if a project has started but the customer decides that completion must be accelerated, a shorter completion time might only be achieved if:

• More money is made available for the extra resources needed to accelerate work needed
• The defined project tasks are reduced

Quality lives in the middle of the Iron Triangle

The balance between the three constraints helps to determine the quality of the project overall, and there is always a give-and-take element.

Project managers must have the knowledge and experience to explain the impacts of shifting any of the three constraints, and then help the client and other project stakeholders to make better informed decisions to meet quality goals.

In short, if you shift scope, time, or cost you will affect quality. Therefore, if you want quality to remain intact, you must maintain balance of the Iron Triangle.

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