The triple constraints of Scope, Budget and Time is widely used in project management practices, trainings and publications. The “iron triangle” showing the 3 constraints together (with sometimes Quality or Customer satisfaction in the middle) – with the explanation that if one of the constraint is moving then the other are very likely to be impacted – became a reference in the profession.
Project manager job advertised will ask for PMs able to manage those constraints. Candidate are usually used to this as well.
But things are changing. The triple constraints has officially been enhanced in the latest version ofPMBOK (4th edition, page 6). Now the competing constraints include BUT are not limited to: scope, quality, schedule/time, budget, resources and risks. So other constraints could be considered such as customer / stakeholders satisfaction, environmental impact, etc…In other words the triangle is obsolete.
This is the acknowledgement that a project’s environment is complex and subject to many internal and external constraints, this has become visible with the expansion of virtual teams, outsourcing, off-shoring, public concerns about the environment, real-time information and all those factors that are forcing organisation to be more adaptable and more in contact with its environment. What it means for projects is that they operate with more and more constraints.
Human Resources: projects are fighting against each other for human resources shared across projects. At the same time, effort spent on project are monitored more closely and charged to the project. Project managers have therefore to consider the HR constraints with a lot more care.
Quality: with the growth of outsourcing and externalisation, more and more projects involve buyer-supplier relationship. This means that often “quality” is contractually defined, mandatory to deliver. The importance of quality has therefore increased dramatically for project managers.
Risks: sources of risks are increasing, there are more technology risks, risks linked to the complexity of the project teams relationships is increasing as the number of different organisations involved in a same project is increasing, market risks are changing with product development length being reduced.
With every project I start I always ask the sponsors “where is the tolerance?”, they always look baffled. The tolerance is basically deciding, if something goes wrong, what constraints is the most flexible: do I change the scope to meet the time commitment? do stick to the scope and allow some slippage? if I have to stick to the budget then shall I remove some of the scope?
Understanding the tolerance gives the project team so strong indication about the project’s environment and priorities. I found that this is extremely important to focus the team.
One way to visually represents the tolerance and constraints to use a Radar chart with a scale of your own (in our example 0 to 6). The higher the number the more important the constraints. In order example Budget and Resources are set to 6 so it will be hard to change them (upwards of course), Risks are at 6 as well, meaning that trying to not mitigate risks is not an option. On the contrary Quality has a low number, meaning that if the quality of the end product suffers then it’s “OK” (not sure if that’s a real life example!).