The basics of critical chain project management

Imagine you’re a kid playing with building blocks. You can build whatever you want, but you only have a set number of blocks available to you. As you go, you pull your resources from the stockpile of blocks available. But what happens when you use all of your resources? How do you ensure that you can build what you want to build using the blocks you have? 

This is the concept behind critical chain project management. 

What is critical chain project management?

Critical chain project management (CCPM) is a project management methodology that helps you monitor essential resources and prioritize dependent tasks—so you can complete projects as efficiently as possible. If your team is looking to carefully monitor the usage of resources, critical chain project management is a good strategy to keep track of those resources.

The history of critical chain project management

Dr. Eliyahu M. Goldratt developed the concept of CCPM in 1997. CCPM relates very closely to one of Dr. Goldratt's other theories—the theory of constraints. The theory of constraints helps you identify key bottlenecks or limiting factors standing in the way of your project's completion. The idea is that every project has one main constraint and this constraint has the ability to disrupt the entire project by breaking the weakest chain. 

The critical chain method vs. the critical path method

These two forms of project management are very similar but have one major difference. The critical path method focuses on the single string of concurrent tasks required to complete a project. While other tasks may need to be completed, the critical path highlights all of the tasks that are absolutely necessary for the project's completion. This form of project management can help teams identify the most optimal workflow to create an efficient project timeline. Any tasks that are not part of the critical path are relegated to a lower priority. Project health is dictated by whether or not certain critical tasks are completed by a certain time. 

The critical chain method also focuses on task dependencies,

but it also considers the resources needed to complete a project. Because there are so many unknown variables that can contribute to resource constraints, the critical chain method builds resource buffers (excess resources to act as a barrier) into the project timeline. Unlike the critical path method, which only focuses on when tasks are completed, the critical chain method dictates project success by how quickly resource buffers are consumed. If your team hasn't used any resource buffers, your project is progressing successfully.

The components of a critical chain

There are three main parts of a critical chain: the critical path, the feeding chain, and resource buffers. 

The critical path

The critical path is the longest sequence of dependent tasks that need to happen to complete a project. In other words, it’s all of the tasks that are absolutely necessary for a project’s success, laid out in the order in which they need to be completed. In the critical chain method, it’s important to understand that there are different levels of dependencies. The critical path holds the main level of dependencies, or project critical tasks, and if a task doesn’t affect the critical path, they are delegated to a different path, also known as the feeding chain. 

The feeding chain

The feeding chain is a secondary chain of dependent tasks that need to run concurrently with the critical path. Each feeding chain eventually merges with the critical path. This is because the string of events in the feeding chain only affects one of the tasks on the critical path. The feeding chain needs to run at the same time as the critical path to prevent any delays within the critical path.

Let’s take a look at the critical path and the feeding chain in a simple example. Say you’re planning a work party. Your critical path looks like this:

• Decide on a theme

• Send out party invites

• Find a venue

• Host event

While these are still steps to the critical path, there are some tasks in a feeding chain that must happen in tandem with the critical path. For example, before sending out party invitations, the team needs to decide who to invite. Before hosting the event, they need to purchase decorations according to the theme, and set up the event. These are all examples of tasks that are in a feeding chain.

The resource buffers

Buffers are safeguards built into the resources of the critical chain to ensure a project runs smoothly. Like bumpers in a bowling lane, these buffers are designed to give projects extra wiggle room in the event that something doesn't go according to plan. 

There are three types of buffers commonly used in the critical chain project management methodology: 

• Project buffers: The extra time that's placed between the final task and the end of the project. Adding an extra chunk of time before the expected due date gives team members a chance to catch up on any outstanding project tasks they couldn’t get to earlier. 

• Feeding buffers: The extra time that's placed between the feeding chain (also known as the non-critical chain) and the critical chain. Adding this buffer into the timeline prevents any delays from the feeding chain affecting the critical chain. 

• Resource buffers: These are literal resources you set aside in case the critical chain is in need of extra supplies—like extra team members to have on hand, additional equipment, or help from a third-party. 

4 steps for using the critical chain project management process

If you’re new to using the critical chain project management process, try these four steps to get you started.

1. Identify the critical path first

When you're using the critical chain method, the critical path is the spinal cord of your entire project. It's the entire basis of planning, so figuring out what individual tasks make up that core chain is extremely important. 

2. Determine the exact amount of resources your project requires

In this instance, resources can refer to the amount of time your team members need, the actual products and tools your team uses to create the end result, or the actual workers needed to complete a task. 

If you can, estimate how many resources you'll need to complete this project. Estimate how many people it will take to complete a specific task on the critical chain, and approximately how long it will take them. Do this for every task laid out on the critical chain. Based on these calculations, do you have enough resources to complete this project?

If you have any known resource constraints, such as team members leaving due to vacation, you can plan around those constraints. This is one of the major benefits of using the critical chain methodology—the bulk of the project planning happens before the project even begins. 

3. Place your buffers

Once you determine the required resources for the critical path and feeding chains, it’s much easier to identify where to place buffers and how much time or resources your buffers should include. This will give you an opportunity to calculate the buffers you should build based on the requirements you’ve already calculated when creating the critical path. When a project manager is handling buffer management, they can help maintain resource availability and prevent any bottlenecks. 

4. Keep team members focused

Multitasking is your team’s worst enemy. When your team members have to switch between different projects or different tasks, their focus can become fragmented and it can be harder for them to produce work at their typical quality and speed. 

To ensure your team members can stay on track with the project schedule, don't assign one person too many different tasks. If you keep them oriented on one project or one task, they're more likely to stay focused. Ensuring team members aren't working on too many different projects at once can also help prevent context switching, which can lead to stress and burnout. 

Plan your critical chain with a work management tool

Make critical chain scheduling simple by using a work management tool like Asana to help keep your entire team on track. With features like Timeline, team members can quickly get an understanding of task durations, completion dates, and critical resources all in one place.