Best Practices for Balancing Iron Triangle in Software Development

April 26, 2023 • 243 Views • 12 min read

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Bohdan Vasylkiv

CEO & Co-Founder

Regardless of the industry, each development project success depends on project management. In other words, how you manage your project, and what methods or approaches you use during the development, directly impacts the potential result. Thus, the planning stage has an essential role in any work.

If we will be more specific and will narrow down our field of interest strictly to software development estimation, as a part of any software project, then we will face the development iron triangle concept. As a matter of fact, it is one of the most well-spread methods of project management, estimation, planning, and implementation. So, what is so special about this “iron triangle of software development” and how your project can benefit from it?

Iron Triangle of Software Development Explained

As was said before, the development iron triangle model is a very popular approach to software development estimation and planning, which is also used during the development process itself as a guidebook or example, which helps to better understand the available resources and terms of your development.

One of the common delusions is that the project management pyramid consists of only 3 main terms. Frankly speaking, there are 4 different co-dependent units:

  • Scope, or goals and the scale of work to be done within the project development process;

  • Time, or the project schedule/road map of the project, the available terms, within which your team should develop the project, and that can include various time frames for specific features or functionalities to develop;

  • Development Budget, or the number of available resources, mainly finances, allocated to the project;

  • and Quality, or the potential result, achieved goals and expectations, which vary, depending on what priorities you will set up during the development.

As a result, combining all triple constraints, you will get a so-known project management pyramid, or iron triangle of software development if you wish, where the vertices of the triangle are representing scope, time, and project budget, and the middle of the development triangle represents the quality, i.e. the potential success rate.

How Triangle Model Work?

So, we have 3 main constraints, the combination of which defines the final Quality results. But how this principle works? Frankly speaking, the main concept is extremely easy: you have to find the right balance within all the constraints. For instance, if you are cutting the development budget, then you will have to balance the project management pyramid by increasing the rest constraints (Time and Scope).

However, it is hard to imagine the circumstances, when clients will give up the project scope of work. Clearly, everyone wants to get the maximum possible result with the minimum resources. Therefore, there is an alternative way of fixing the triangle - changing the Time aspect. In other words, if you don’t want to cut the required scope of work while cutting the expenses, then you will have to extend the time constraint in order to balance the quality.

As we stated before, each of these development iron triangle constraints is codependent and requires balance. One of the greatest advantages of the triangle, though, is that it works in both ways. To rephrase it, any changes, related to a single component, are resulting in relevant changes in the other key factors. And it works both ways, no matter if you are increasing or decreasing the part of the development budget or other elements.

So, there will be no cost vs quality opposition: if you increase the budget, then you can decrease the time, allocated to the project, or add some extra points to the Scope of work, i.e. add some other features, etc. However, there are some other working schemas or priority metrics, possible within the iron triangle of software development.

Prioritizing Project Management Pyramid

Another advantage of the triangle model is its flexibility. Instead of blindly using this approach, various project managers were experimenting with the possible variations and priorities within the framework.

Sometimes, it is impossible to balance all the elements correctly. On the one hand, the main working principle of the development iron triangle says, that Scope, Time, and Budget metrics should be balanced. However, in some cases, the development budget might be reduced, while there is no way to implement enough changes within the rest constraints. Therefore, to ensure the final result and avoid cost vs quality opposition, project managers use the “fixed” method, by defining one of the elements at the very beginning and balancing the rest, in accordance with the unchangeable component.

Frankly speaking, this fixed resources method is a great approach for agile projects. However, if your software project grows bigger, the number of dedicated teams increases, as well as the scale of work, or its complexity, fixing resources won’t help you. To make it simple, the iron triangle of software development is a great choice for agile teams with short-time planning, yet it won’t work as supposed in a long-term perspective.

Fixed Cost vs Quality

The first and, probably, the most obvious way to fix resources is to set a fixed cost for the project. This principle is similar to the difference between time and resources vs fixed price software development agreements.

As a result, by prioritizing the maximum resources, spend on the project, your project team will be able to adjust the rest constraints of the project management pyramid, perform the estimation and set the rest goals, in accordance with the resources. Clearly, in such a case, the time component is most likely not the only element to be changed. As a result, with limited finances, and time, your team will be able to develop fewer features, i.e. Scope of work will decrease as well.

Still, this is one of the reasons, why the iron triangle of software development is so beloved and popular in projects, based on agile software development life cycle. For instance, instead of setting predetermined and fully fixed resources for the entire project, the development team can set small, yet balanced project management triangles for each sprint or scrum cycle, depending on the method you have chosen.

Fixed Time

Plainly speaking, this approach is almost the same, as the fixed budget. The only major difference is that in this case, you will have to predefine the deadline for the development. Once again, it is rather an agile over plan-driven approach, meaning, that the most effective way to fix time resources - is to do so for a limited task, not the whole process development life cycle.

When you choose the fixed time, then you will have to adjust the scope and budget in order to achieve the goal and desirable quality. Once again, we are talking about a short-time period. For example, you can choose a fixed-time strategy for developing a certain feature or part of a software project, like setting up MongoDB or any other database environment, ensuring its work within the backend, etc.

Fixed Scope

Judging from our experience, it is the least popular fixed resources approach, at least, in terms of the development iron triangle principle. Fixing the scope makes the development process more similar to waterfall project management when there are set goals, while the budget and time are more abstract and variable.

It can be a better idea to use it in a more traditional long-term development, because it gives enough flexibility, yet clarifies the required result. Still, it might be too general for agile development, which can result in extra prolongations or additional resources.

Fixed Combination

Finally, the iron development triangle supports the possibility of combining priority elements. The main principle, though, is the same. In these cases, you choose two or three priorities, like Time and Scope, Scope and Budget, and Budget and Time, or even Fixed Time, Scope, and Budget.

So, if you combine two different constraints, you will have to adjust the third one. Nonetheless, you might wonder what is the reason for fixing all the elements. The answer is simple, yet unobvious - it is being done to make an estimation for very specific requirements and gives a possibility to immediately answer whether it is possible or not to deliver such a project in predefined terms and with a fixed budget.

How to Estimate Development Project?

Eventually, it seems, that despite all the advantages of the software development iron triangle, it might be not an all-in-one planning solution. Clearly, it can be a great and simple tool for pre-estimation and a management method, used during agile development.

Still, estimation is a much scalable and complex task, which requires more than balancing the resources. In other words, sometimes it requires more details. Therefore, the estimation can, and probably should be performed with the use of other methods. Frankly, the easiest way to do so - is to contact an outsourced company.

Plainly speaking, each outsourcing vendor provides estimation and planning services as one of the services. For example, here, in Incora, we include this service with the rest. So, when you will decide to collaborate with us, we will start with estimation. This will help us both to better understand the scale of work and the number of needed resources, plan the development, etc. For a more detailed illustration, we encourage you to consider our case studies, where we explain the projects, we worked on, in more detail.

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What is the Iron Triangle in software development?

The Iron Triangle refers to the three constraints of software development: time, cost, and scope. The idea is that these three factors are interdependent and a change in one will affect the others.

How do I balance the Iron Triangle?

Why is it important to balance the Iron Triangle?

How do I prioritize tasks when balancing the Iron Triangle?

What are some techniques for setting realistic expectations when balancing the Iron Triangle?

How do I monitor and adjust when balancing the Iron Triangle?

What are some common mistakes to avoid when balancing the Iron Triangle?

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