Critical path and critical chain are two commonly used methods when it comes to project schedule management.
While both of these techniques have their merits and demerits and sound very alike, I can assure you that they’re quite different.
It’s important that you have a good understanding of these differences in order for you to choose the best approach for managing your project successfully.
In this post, we’ll discuss the critical chain vs critical path and compare the two methodologies in-depth.
What is Critical Path?
The critical path is a project management methodology that’s used to identify the longest sequence of activities required to complete a project.
It’s an approach that’s based on the idea that you can’t complete a project until all the project tasks are completed.
Therefore, the critical path is the series of activities that must be done on time if the project is to be completed on schedule.
To determine the critical path as a project manager, you need to identify all of the tasks required to complete the project and the duration of each.
The critical path will help you to identify the most important tasks of the project so you can focus on completing them on time.
What is Critical Chain?
An alternative to the Critical Path Method is the Critical Chain method which works with the assumption that project schedules should be flexible and adaptable rather than fixed.
The critical chain is a project management methodology that focuses on resource management and project uncertainty reduction.
It’s founded on the theory of constraints, which emphasizes the significance of identifying and managing the constraints that limit the performance of a project.
This method accounts for uncertainties and delays in the project with buffers, which can help ensure that the project is completed on time.
Instead of attempting to complete the tasks by a fixed deadline, the project team focuses on completing them within the buffer time.
Critical Chain vs Critical Path
From the descriptions of these methods, you probably are starting to have an idea of how they may have similar goals of ensuring the project is completed within schedule but go about it in different ways.
To further understand the key differences between them, here’s a comparison of their distinguishing features:
1. Focus
While the critical path focuses on determining the longest sequence of tasks required to complete the project, the critical chain, on the other hand, focuses on resource management and reducing project uncertainties.
2. Time Buffers
Time buffers, which are added to task durations to account for uncertainty and variability, are not used on the critical path.
The critical chain, on the other hand, employs time buffers to protect the project from delays and increase its chances of success.
3. Resource Management
With the critical path, it’s assumed that resources will be available when needed and resource constraints are largely ignored.
The critical chain, on the other hand, takes into account resource availability and constraints, and it employs resource leveling to balance resource demands.
4. Task Dependencies
For the critical path, task dependencies are used in determining the order in which project tasks should be done.
The critical chain, on the other hand, focuses on resource dependencies, which are the relationships between tasks and available resources.
5. Flexibility
The critical path is less flexible than the critical chain because it doesn’t allow for project delays or changes.
The critical chain, on the other hand, is a flexible approach that employs time buffers to accommodate project schedule changes and uncertainties.
How is Critical Path Calculated?
The Critical Path Method (CPM) is used to calculate the Critical Path. It’s a mathematical algorithm that analyses the project schedule to determine the critical tasks and overall project duration.
The Critical Path Method (CPM) consists of the steps listed below:
1. Identify Activities
The first step in calculating the critical path is to identify all of the project’s activities.
This entails the decomposition of the project into smaller, manageable tasks that can be easily estimated in terms of time and resources needed.
2. Determine Dependencies
After all of the activities have been identified, the next step is to determine the dependencies between them.
Dependencies are the relationships that exist between activities and can be finish-to-start, start-to-start, finish-to-finish, or start-to-finish.
3. Create a Network Diagram
A network diagram is a graphical representation of the project schedule that demonstrates the relationships between the activities.
You can create one using software like Microsoft Project or with a simple flowchart.
4. Calculate Early Start and Early Finish Times
Based on the dependencies and duration of the activity, the early start and early finish times represent the earliest possible start and finish times for each activity.
The early start time of an activity is the sum of its predecessor activities’ early finish times, whereas the early finish time is the sum of the activity duration and the early start time.
5. Calculate Late Start and Late Finish Times
The late start and late finish times represent the latest possible start and finish times for each activity without causing the project completion date to be pushed back.
The late start time of an activity is the shortest of its successor activities’ late finish times, whereas the late finish time is the difference between the project completion date, the activity duration, and the late start time.
6. Calculate the Total Float
The total float is the amount of time that an activity can be delayed without affecting the completion date of your project.
It’s calculated as the difference between late start and early start times, or late finish and early finish times.
7. Identify the Critical Path
The critical path is the longest sequence of activities that determines the overall duration of the project.
It’s defined by activities with zero total float, which means they cannot be delayed without delaying the project’s completion date.
Advantages of the Critical Path Method
The Critical Path Method is a popular choice among project managers because it has a lot of advantages. These include:
1. Helps Identify Critical Tasks
As a project manager, the Critical Path Method enables you in identifying the critical tasks that must be completed on time to ensure the project’s success.
This way, you can concentrate your efforts and resources on these tasks, ensuring that they are completed on time and within budget.
2. Helps Determine the Project Schedule
Creating an accurate and realistic project schedule is key to managing a project successfully.
By identifying the critical tasks and dependencies for your project, you can create a schedule that takes into account the time and resources needed to complete each task.
3. Helps Manage Project Resources
The critical path method is helpful in effectively managing project resources.
You can ensure that resources are allocated to critical tasks in a timely and efficient manner by identifying critical tasks and their resource requirements.
This avoids resource conflicts and ensures the project is completed on time.
4. Helps Identify Risks and Uncertainties
Risk identification is crucial for any project. With the critical path method, you can identify risks and uncertainties that may impact the project’s completion.
You can also identify potential delays or resource constraints and develop contingency plans to mitigate them by analyzing the critical path and its dependencies.
5. Helps Improve Communication
The critical path method aids in the improvement of communication among project team members.
Team members can easily understand their roles and responsibilities, as well as the timeline for completing their tasks if a clear and concise project schedule is created.
This reduces confusion and ensures that everyone is working towards the same objectives.
Disadvantages of the Critical Path Method
Despite the numerous advantages of the Critical Path Method, like every methodology, it’s not perfect and there are disadvantages that you need to be aware of.
These include:
1. Time and Resource-Intensive
Implementing the critical path method effectively takes a significant amount of time and resources.
To identify the critical path, you must carefully analyze the project’s activities and their dependencies, which can be a really time-consuming process, especially for mega projects.
2. Lack of Flexibility
The critical path method does not allow for much project schedule flexibility.
After identifying the critical path, any delays or changes to the schedule can have a significant impact on the project’s completion date.
3. Lack of Focus on Quality
The critical path method prioritizes the completion of the project on time over the quality of work. This can result in rushed or incomplete work, which can jeopardize the project’s success.
4. Lack of Consideration for External Factors
The critical path method works with the assumption that all activities are to be completed on time and within budget.
However, life happens during projects and there are external factors such as weather or supplier delays that may have an impact on the project’s completion, disrupting the critical path.
5. Lack of Consideration for Resource Constraints
The critical path method also assumes that resources are readily available for all activities.
However, in reality, resources may be limited or unavailable, affecting project completion.
Components of a Critical Chain
There are 3 main components of a critical chain that you need to understand as a project manager. These are:
1. The Critical Path
Yes, the critical path is actually a part of the critical chain. As earlier iterated, the critical path is the sequence of tasks that must be completed in a specific order in order to complete the project on time.
It’s the longest path through the network diagram and indicates the shortest amount of time needed to complete the project.
The critical path is important because any delay in completing a task on the critical path causes the entire project to be delayed.
Using the critical path can greatly help you in identifying and prioritizing the most important tasks.
2. The Feeding Chain
The Feeding Chain is a series of non-critical tasks that provide resources to the critical path.
It includes tasks that must be completed prior to the start of critical path tasks as well as tasks that can be completed concurrently with critical path tasks.
Because any delay in completing a feeding chain task delays the corresponding critical path task, the feeding chain is also critical.
3. The Resource Buffers
The resource buffers are time buffers that have been added to the project schedule in order to protect the critical chain from resource uncertainties and variations.
There are 3 types of resource buffers. They are the project buffer, the feeding buffer, and the resource buffer.
To protect the project completion date, the project buffer is added to the end of the critical chain.
And to protect the critical path tasks, the feeding buffer is added at the end of the feeding chain.
While each task receives a resource buffer to protect against resource uncertainties and variations.
Steps for Using the Critical Chain Method
Using the critical chain project management process consists of several steps that you must complete in order for your projects to be successful.
These four main steps are the core of the critical change project management process:
1. Identify the Critical Chain
To use this approach, you must first identify the critical chain, which is the sequence of tasks that must be completed in a specific order in order to complete the project on time.
This entails drawing a network diagram of all the tasks and identifying which are critical and which are not. The critical chain is the project’s backbone, and it determines the overall project completion date.
2. Estimate Task Durations and Resource Requirements
Next, you need to estimate the duration of all project tasks and the resources required to do them.
When doing this, you must factor in the availability and constraints of resources like people, equipment, and materials.
Also, your estimates need to be as accurate as possible in order to create an effective and realistic project schedule.
3. Create the Project Schedule
After you have gotten your task durations and resource requirements estimates, then the next step is creating the project schedule.
This entails scheduling tasks in such a way that resource conflicts are minimized and resources are available when needed.
The project schedule should be achievable and realistic, taking into account any uncertainties or risks.
4. Add Resource Buffers and the Project Buffer
The final step is to add resource buffers to each task as well as the project buffer to the critical chain’s end.
The resource buffer protects against unexpected delays or resource constraints, whereas the project buffer protects against the overall project completion date.
These buffers should be sized based on the project’s level of uncertainty and variability.
Advantages of the Critical Chain Method
The Critical Chain Method has lots of advantages that could make it ideal for your project. These include:
1. Improved Resource Management
The Critical Chain Method focuses on resource management, which allows you to maximize resource utilization while minimizing waste.
It ensures that resources are used efficiently and effectively by identifying resource constraints and scheduling activities accordingly.
2. Increased Flexibility
Unlike the Critical Path Method, this method allows for some project schedule flexibility.
The use of resource buffers can assist in absorbing unexpected delays or schedule changes without affecting the project’s completion date.
3. Focus on Quality
The Critical Chain Method prioritizes quality over simply completing the project on time.
By identifying the critical chain and resource constraints, you can ensure that your project is completed to the highest possible standard.
4. Reduced Project Duration
By identifying the critical chain and focusing resources on completing those activities first, the critical chain method can help reduce the overall duration of the project.
This can help the project be completed sooner, which is advantageous in highly competitive industries.
5. Increased Project Success
The Critical Chain Method has been shown to improve project success rates.
It ensures that projects are completed on time, within budget, and to the satisfaction of stakeholders by focusing on resource management and quality.
Disadvantages of the Critical Chain Method
The Critical Chain Method also has its drawbacks and these include:
1. Complexity
Because it requires a thorough understanding of the project’s resource constraints and the critical chain, the Critical Chain Method can be more complex than traditional project management methods.
This complexity can make implementation and management difficult, especially for smaller projects.
2. Lack of Historical Data
The critical chain method is a relatively new project management technique, and therefore there may be a lack of historical data available to assist in planning and executing projects using this method.
This can make estimating project timelines and resource requirements difficult.
3. Resistance to Change
Like most relatively new methodologies, adopting the Critical Chain Method may necessitate a significant shift in project management culture and practices.
Having some team members exhibit resistance to these changes isn’t uncommon and this can jeopardize the project’s success.
4. Potential for Over-Optimization
The Critical Chain Method emphasizes resource optimization, which can lead to over-optimization and inefficiencies.
This can happen when there is too much emphasis on resource utilization at the expense of other project factors like quality or stakeholder satisfaction.
5. Limited Applicability
Also, the Critical Chain Method may not be appropriate for all types of projects.
Projects with a low level of uncertainty, for example, or those requiring a high level of creativity, may not be suitable for the critical chain method.
Choosing Between Critical Chain and Critical Path
Managing a project will throw lots of choices at you, and your ability to decide by looking at the nuances of your project and what’s best for it is key.
If you have to choose between the Critical Chain and Critical Path methods, you need to consider the needs of your project.
The Critical Path Method may be more suitable for projects with fixed deadlines and where timing is critical.
This method can help to provide a clear timeline and prioritization of tasks, which may be necessary for completing the project on time.
While the Critical Chain method may be more appropriate for projects with more uncertainty and where adaptability is key.
This method allows for more flexibility and can account for delays and changes in the project schedule.
However, this method may require more planning and coordination, and it may be more time-consuming than the Critical Path method.
Also, It’s important to consider the resources available for the project. The Critical Chain method may require more resources, including more time for planning and coordination, as well as more monitoring and control.
The Critical Path method on the other hand may be less resource-intensive, as it focuses on completing tasks within a fixed schedule.
Conclusion
Overall, the Critical Chain and Critical Path methods are both very reliable tools for managing and scheduling various types of projects that you may come across.
Both methods have their advantages and disadvantages, and it is critical to weigh these factors before making a decision.
Ultimately, if you do your project analysis well, you will have a clear idea of what your project needs to be completed within schedule, budget, and expected quality, and it becomes easier to go with an approach tailored to that project.
FAQs
Can the Critical Chain be Longer than the Critical Path?
Yes, the critical chain can be longer than the critical path as buffer time is added in the critical chain method to account for uncertainties and variability, which can make the critical chain longer than the critical path.
Can the Critical Chain and Critical Path Methods be used Together?
Yes, the Critical Chain and Critical Path methods can be used in conjunction with one another in project management.
The Critical Path Method aids in determining the sequence of tasks that determine project duration, whereas the Critical Chain Method aids in managing uncertainties and variability by adding buffer time.
Project managers can create a more comprehensive project plan that takes into account both time and resource constraints by combining these methods.
Can we have Multiple Critical Paths in Project Management?
Yes, it’s possible to have more than one critical path in project management. This occurs when there are multiple paths with the same duration and critical activities.
