Beyond the Triple Constraints

Abstract

To define project management success, the Triple Constraint (also called the Iron Triangle) has traditionally been applied in order to balance between key factors that constraint the overall project delivery. Regardless of a project´s size and degree of complexity, there will always be constraints to bear in mind throughout the whole project. The Triple Constraint model points out that a project manager is assumed to reach a reasonable and balanced trade-off between competing and visible constraints, in order to deliver in time, cost and scope.

After including quality as one of the key constraints, other constraints have also proved to be essential in project management. Factors such as; Resources, Customer Satisfaction, Risk and Expectations. Regardless of the constraint model´s shape, the constraints depend greatly on each other and will be adjusted depending on the particular project. This paper will outline the traditional approach of the Triple Constraint, together with some project success factors beyond the three primary objectives and the relationships between them.

In reality, a project manager is challenged by numerous constraints apart from the “measureable” mentioned factors; A project needs ground rules for communication and behavior, in addition to awareness around the individual´s needs for motivation and confirmation. These “soft pyramid sides” are related to internal satisfaction, and have traditionally been considered as complementary to the core trade-offs of the Iron Triangle, which will not be sufficient enough in many cases.

Big Idea

The Triple Constraint model is formed by three dimensions; time, cost and scope, and one side of the model/triangle cannot be changed without affecting one of the other sides. Briefly explained, scope represents the total amount of work involved in delivering a project, cost refers to the total costs of carrying out the project and schedule/time reflects the estimated or allotted time set till project delivery.

Purpose

The model has been used since the 1950s, and project managers have been measured by their ability to balance the key factors/constraints of scope, cost and schedule. In the past, projects had somewhat more certainty in outcomes, as the main source of uncertainty was in the technology that was taken into use. The model used to provide metrics for management measurement, evaluation and control, resulting in a clear and visible evaluation of how well projects were carried out after they were finalized. In addition, the model provided success criteria for evaluating options for decision-making.

Current state

George E. P. Box stated “All models are wrong. Some are useful.” (1979)

Since the 1950s, the uncertainty in projects has increased, which in turn has led to a reduction of the model´s efficacy. With more uncertainty, the constraints of the model start to cause, not solve, issues. Moreover, when using the model project managers focused on satisfying constraints, instead of focusing on customer satisfaction. This results in a project delivery within the allotted time, but the customer will not be satisfied by this. Yet, since the project was delivered near budget, it was often considered successful.

For project nowadays, the extent of uncertainty is highly present, indicating that it is impossible to determine a fixed scope, cost and schedule in advance of any project. The three factors of the model that was earlier looked upon as variables, had to be considered as constraints instead.

Application

According to PMBOK® Guide the definition of constraint is: “A limiting factor that affects the execution of a project or process”. The constraint can be both internal and external to a project, but will in some way affect the performance of a project. Project managers often refer to the Triple Constraint model as a framework for evaluating a project.

The three constraints are closely interrelated to each other, and thus, if a project is required to change one of the constraints, the others will be affected. Firstly, there is a direct and essential relationship between time and money. If the time scheduled for a project is reduced, either the budget will need to be increased or the scope needs to be reduced as well. In other words, in case of an exceeded project schedule, it will immediately be costlier for the company to carry out the project. Additionally, the costs estimated are almost certain to be overspent in case of a delayed project start or fulfillment.

According to the PMBOK® Guide (page 6):

“The relationship among these factors is such that if any one factor changes, at least one other factor is likely to be affected. For example, if the schedule is shortened, often the budget needs to be increased to add additional resources to complete the same amount of work in less time. If a budget increase is not possible, the scope or targeted quality may be reduced to deliver the project’s end result in less time within the same budget amount. Project stakeholders may have differing ideas as to which factors are the most important, creating an even greater challenge. Changing the project requirements or objectives may create additional risks. The project team needs to be able to assess the situation, balance the demands, and maintain proactive communication with stakeholders in order to deliver a successful project.” 

All of the three constraints are clear benchmarks against which to judge success when a project is finalized. But, in order to be able to use the constraints as objectives, the project manager needs to understand what each objective implies and how the three can interrelate with each other.

Moreover, there are several examples of time-related costs, such as; (referanse til PM bok):

- The effect of project delays on direct costs; cost inflation occurs when a project starts later than predetermined. Additionally, there will be other causes to inflation, that are less easily quantifiable, e.g. when work beyond scheduled time contributes to further inefficient work performance. - The effect of project delays on indirect (overhead) costs: in case of a delayed project, indirect costs will have to be borne for a longer period than planned. - The effect of project delays on the costs of financing; in case of an extended financing period, the total amount of interest or notional interest payable will increase correspondingly.

Most projects have deadlines, whether they are formal requirements from a client or informal in-house expectations. The purpose of these is to keep a schedule within a planned deadline, and prevent usage of resources long after the original purpose of the project if forgotten. Worst case scenarios related to time-related costs could potentially be unavoidable cost penalties, which can occur if the project exceeds its deadline. This means that the contractor fails to meet the contracted delivery obligation and to avoid this, all projects should aim to monitor and control costs through an achievable plan, so that the project proceeds without time extending disruption.

When talking about the budget of a project, it can be in terms of both money and effort needed to carry out a project. While “scope” refers to the outcome of the project (“products” in PRINCE2™ terminology), and consists of a list of deliverables that need to be addressed by the organization responsible for the project. When the definition of the scope is clear and sufficient detailed, a project manager will lower the chance of any great variation in cost and time. On the other hand, if a project is poorly defined, there is a bigger chance that the triangle will change its shape by great differences.

What about quality?

The difference between quality and scope, is that quality focuses on the characteristics of a deliverable. When describing a project, there is nothing called “high/low quality”. The reason for this is that the definition of “quality” varies according to the stakeholder´s requirements. From a stakeholder perspective, expectations regarding quality are based on individual scope, time and cost limitations. Hence, quality is another triangle within the original iron triangle, where all three sides are linked to the outer boundaries. So, in order for a project to meet its maximum quality level, the inner three-sided quality triangle has to meet the outer triangle, given limitations of scope, time and cost.

Moreover, the quality constraint works in the same way as the other constraints. And there are many classic examples of projects where both cost and time were tightly constrained, which resulted in less testing and verification of quality. In these cases, the model has quality as one of the three corners (substituting scope). In more recent year organizations, total quality management (TQM) have been increasingly embraced. In TQM, a “culture for quality” is created throughout any organization, with quality shared by all the staff and workforce from top management downwards. Furthermore, the ISO 9000 series of standards is widely accepted as a base from which to design, implement and operate an effective quality management system, with the ultimate objective of creating a quality culture throughout the organization. (The International Organization for Standards (ISO) publishes ISO9000 series and a full range of other international standards.)