The Origin of Critical Chain
Critical Chain Project Management was developed by Dr. Eliyahu M. Goldratt in 1997 as a response to the inability to complete tasks on time and within budget. Dr. Goldratt first introduced the method in his work on Theory of Constraints (TOC), which focuses on identifying and fixing bottlenecks in order to improve the entire workflow.
Critical Chain vs Critical Path
The critical chain and the critical path are both project management methodologies that let a manager focus on scheduling projects. Although the critical chain incorporates the critical path, the two methods are different in several ways.
Emphasises the importance of communication between team members to mitigate risks
Doesn’t focus on project communication as much
Focused on risk management, resource allocation, and the use of buffers
Focused on identifying the critical path
Includes buffers to tackle uncertainties ahead
Assumes the project will go according to plan
What Is Critical Chain Project Management?
The critical Chain is the longest path in the network diagram that takes into consideration task dependency and resource availability. It’s a modified form of the Critical Path Method where project activities use aggressive time and, in theory, have access to unlimited resources.
While Critical Path Method uses Float, CCPM uses buffers as strategic points and solutions that eliminate project uncertainty.
There are four types of buffers:
Project Buffer - protects the project from missing its scheduled finish date and keeps the completion date unchanged. It is inserted at the end of the project network diagram between the last task and the completion date. It protects the project completion date, which can vary due to the impact of changes in activity durations in the critical chain. In other words, the size of the project buffer depends on the activities in the critical chain.
Feeding Buffer - is inserted between the last task on a non-critical chain and the critical chain. Feeding chains are activities that merge into the critical chain. Feeding buffers are typically added to those merging points so any delays on a non-critical chain don’t affect the critical chain.
Resource Buffer - these are set on the Critical Chain to ensure appropriate and required resources (people, equipment) are available throughout the project when needed. These resources are commonly known as Critical Resources.
Capacity Buffer - sets on-call resources necessary in case unforeseen budget issues arise.
The Specific Steps in CCPM
Here's a guide to the nine steps you need to take in the CCPM process:
• Reduce all time estimates by 50% (the protection that is cut is inserted as a buffer in the project)
• Level the project plan and remove resource retentions and constraints (in this phase, a critical path is transformed into a critical chain)
• Add a portion of reduced task duration estimation into the Project Buffer and insert it at the end of the project
• Insert Feeding Buffers at points where non-critical chain path meets critical chain path
• Protect the Critical Chain from unavailable resources by placing Resource Buffers where appropriate
• Insert Capacity Buffers where needed
• Schedule tasks as late as possible (this will help you prevent multitasking)
• Encourage aggressive task completion time and emphasize the importance of start time to complete the tasks as quickly as possible
• Manage buffers and gain the information necessary for controlling the plan and taking recovery actions if needed
Here’s a real-world example of CCPM in action. Let’s say you’re building something. You created a plan and built a schedule based on the critical path. Although you have given enough thought to each project stage and started working on it, you suddenly realize there isn’t enough equipment or people to achieve the project's goal on time.
To prevent the project from failing, you consider resource constraints and allocation in your project planning and modify the critical path. Essentially, you change the critical path into a critical chain, and this way, you create a much more realistic schedule.
Why Do We Need CCPM?
The critical chain helps us increase a project's success and efficiency by managing risks, optimizing and monitoring resource allocation, and improving communication.
Traditional project management is based on predictable experience and development tools. But, as much as we would like to be able to control every single aspect of a project, we can’t. In traditional project management practices, much time is spent training to make accurate time estimates and reducing related risks, which delays projects.
The critical Path Method isn’t very helpful either because it’s based on the theory that there are no constraints and that all the resources will be available at any given time, which is not always the case. Also, according to Critical Path Method, if any activity is delayed, the delay will pass on to the next activity and delay the entire project.
Unlike other techniques, Critical Chain Optimization (a huge part of CCPM) helps view which time estimates we can shorten and evenly distribute workload thanks to flexible start times. Finally, Critical Chain Optimization ensures we don’t need a safety margin, and all tasks are completed ahead of schedule.
What Are the Benefits of the Critical Chain Method?
Although CCPM is mainly used in multi-project environments that require a lot of resources, you can apply it on your projects regardless of whether you are running a small company or a big corporation.
CCPM is probably one of the most practical and the most important project management techniques because of several benefits it offers:
• It helps people become more focused on their tasks, thus increasing team productivity and efficiency
• It helps your team overcome the Student Syndrome phenomena (when people begin working more as the deadline starts approaching)
• It avoids mismanagement of floats
• It considers the minimal time needed to complete the project
• It accelerates project completion
• It makes a significant reduction in capital requirements
How To Integrate Critical Chain Into the Workflow
Even though we said that PM tools often lack the options to incorporate CCPM, there are workarounds that allow you to plan critical chain in workflow management software. ActiveCollab is a project management platform that can help you apply any methodology, including critical chain.
First, you should identify the critical chain and its activities. You can create tasks in ActiveCollab, describe them in detail, book and assign them, and attach files. All tasks can be estimated and provided with a due date. This way, you’ll know precisely which activity must be completed at a certain time. The main characteristic of a chain is that its links are connected, just as the activities in a project.
ActiveCollab allows you to create task dependencies and is equipped with automatic rescheduling. This means that if you change the due date of a parent task, the child’s start date will automatically be moved as well.
The three project views let you view tasks as a to-do list, columns, or arranged on a timeline, aka the Gantt chart. Once you insert all the necessary information, it will be much easier to monitor project progress and guide your team and their assignments. The Workload feature lets you monitor everyone’s employment and use resource leveling when needed. All in all, a visual tool that is user-friendly at a small cost, such as ActiveCollab, can help project managers step up the quality game and stay on top of deadlines.
Critical Chain Method and Lean Project Management
Lean and CCPM are popular methodologies that are widely used by project managers in different industries. They both aim to complete projects successfully, but their main focus differs. Lean focuses mainly on reducing waste, while CCPM manages risks and makes sure the project is finished on time. This fundamental difference spreads throughout all aspects. For example, communication and collaboration are very important in both methodologies, but one emphasizes how vital communication between team members is in reducing waste, and the other values collaboration as a way to reduce risks.
Resources are scarce, and all project managers must make the most of what they have at their disposal. Those who work by lean principles will get rid of everything that isn’t effective, while those who follow the critical chain will use every possible resource to decrease the likelihood of delays or risks.
Another difference between these two methodologies is in project execution and management. Lean will break down a project into smaller groups of assignments, and CCPM will create a chain of events, find the dependencies between them and insert buffers to make sure all risks are covered.
Some say the critical chain is a hybrid between Agile and Waterfall. It can be considered an improved version of Waterfall as it's more flexible when it comes to sequencing activities and more focused on allocating resources adequately. The critical chain can also be executed through Agile principles, making it a very adaptable methodology.
Disadvantages of Critical Chain Methodology
The critical chain methodology isn’t very useful nor adequate for small projects. They can be managed better using other methods like Kanban, Gantt charts, or Scrum. On the other hand, large projects may benefit from CCPM, but they’ll still encounter issues like inflexibility and complexity.
Making changes on the go isn’t as easy as in other project management methodologies. Every alteration requires new task estimations and making sure the critical chain is not endangered. Another drawback is that most PM tools don’t support this methodology which makes it more difficult to implement.