The critical path method, or CPM for short, is a very important method used in project management. Project managers are tasked with the challenging responsibility of coordinating resources, talent, budgets, and expectations to ensure the successful and timely completion of projects. When executed effectively, the critical path method provides invaluable guidance to project managers in managing these aspects proficiently.
This comprehensive guide explores the concept of the critical path method (CPM) and its beneficial implications for businesses. In addition, we have tried to explain the critical path method with a practical example.
Contents
What is the Critical Path Method (CPM)?
The critical path method, or CPM for short, is used to determine the longest sequence of interdependent tasks in a project. Ensuring the timely completion of these tasks allows for the earliest possible project completion date. Additionally, it highlights tasks that can run concurrently with critical tasks, providing more leeway for completion. By giving precedence to tasks lacking buffer time and arranging other tasks accordingly, project managers can effectively maintain project momentum toward timely completion.
The Critical Path Method (CPM) was used in 1956, by DuPont. Initially utilized in construction and engineering, it has since become a staple in project management. To effectively implement CPM, certain prerequisites must be established:
- Define the project’s workflow structure, outlining each stage.
- Provide estimates for task durations.
- Determine logical relationships between activities.
CPM stands out as the predominant network analysis technique in project management due to its simplicity and reliance on elementary arithmetic for calculations. Automation tools and software have been developed to streamline CPM processes.
7 Benefits of the Critical Path Method
The critical path method provides project managers with several benefits, facilitating budget control, efficient scheduling of resources and talent, progress monitoring, alleviating project management burdens, as well as enabling progress tracking and scope management.
The benefits of the critical path method can be explained as follows;
1) Streamlined Budget Management
By establishing a clear roadmap for project completion, you can minimize wasted time and optimize resource allocation. For instance, identifying float time in certain tasks enables the reallocation of employees to critical path activities, mitigating unnecessary idle time and reducing costs. A detailed project breakdown facilitates the efficient allocation of resources. Thus minimizing inventory storage expenses.
2) Efficient Time Management
In addition to reallocating employees from tasks with excess float time, project managers can strategically assign them to tasks with buffer time. For instance, employees in the learning phase can be assigned to tasks with float time to facilitate skill acquisition, while seasoned employees can handle critical path tasks without buffer time.
3) Streamlined Project Management
Instead of viewing a large, intricate project as a whole, the critical path method deconstructs it into manageable steps. This approach enables project managers to focus on handling tasks individually as the project progresses, simplifying resource, budget, and talent management.
4) Effective Resource Management
By utilizing the critical path method, project managers gain clarity on the timing of every activity and the corresponding resource requirements. Consequently, resource allocation becomes straightforward, ensuring resources are directed where needed throughout the project timeline. Moreover, it facilitates the reallocation of resources from non-critical activities to urgent tasks as necessary.
5) Effortless Project Management
Utilizing the critical path method entails breaking down the project into manageable segments through clear charts, often integrated into project management tools. This approach establishes a straightforward progress checklist for monitoring. By delineating the project schedule, project managers can easily track the project’s progress daily and ensure timely completion.
6) Straightforward Reporting
Project management software aids in identifying the critical path of a project. Subsequently, these charts are utilized to assess real-time progress. Ensuring the project remains on schedule and adequately resourced. Consequently, reports are continuously updated and readily accessible for immediate, transparent reporting.
7) Enhanced Scope Management
By following the critical path, project managers can readily identify if a specific task is consuming more time or resources than initially planned. Any deviation from the intended critical path serves as a warning sign for potential scope creep. It encourages project managers to immediately implement change management strategies to prevent it from going beyond control.
CPM Glossary
Some of the terms used in the critical path method and their definitions are as follows;
- Work (Activity): The realization of a task required for the completion of the project.
- Event: Indicates the ON (Start) and OFF (End) moments of a job.
- Network: You can complete the project with a diagram representing the relationships of the activities. The network is either an arrow diagram or a priority diagram.
- Duration – D: The time required to perform a task.
- Early Start – ES: The earliest time a job can start.
- Early Finish – EF: The earliest time a job can be finished.
- Late Start – LS: The latest time a job can start.
- Late Finish – LF: The latest time when a job can be finished.
- Total Float – TF: The maximum time a job can be delayed without increasing the project’s completion time.
- Free Float – FF: The total time a job can be delayed so as not to delay the earliest start time of the next job.
You can also access the list of “Critical Path Method (CPM) Scheduling Terminology” published by the State of Michigan at THIS LINK.
How To Find the Critical Path in 6 Steps?
We wanted to explain how to find the critical path using the example of a baby shower party, which could be a construction project, the production of a product or the planning of a trip. The logic works in the same way.
1) List Project Activities
When developing a project management plan, it’s common to create a work breakdown structure to streamline the process. Utilize this structure to outline all necessary activities for each milestone of your project.
If a work breakdown structure hasn’t been established yet, it’s imperative to identify all activities required to achieve the project’s final deliverable. For example, let your project be planning a baby shower party. Tasks to be done might include initial meetings with the couple, preparing a guest list, and liaising with the venue. List all the tasks necessary for the preparation of the event.
Next, assess the time needed for each task. For instance, allocating two days to gather the couple’s preferences, budget, and baby shower party date, and a week to secure a venue. Continue estimating durations for all tasks and organize them into a table format. Each task should have a task ID (such as alphabetical letters), a descriptive name, and a duration specified in the most suitable time unit for your project.
| Task ID | Task | Task Duration (in Days) |
| A | Project start | 0 days |
| B | Find out the couple’s wishes and baby shower party date | 2 days |
| C | Write a guest list | 7 days |
| D | Book a venue | 7 days |
| E | Prepare an invitation | 14 days |
| F | Design and send save-the-dates | 21 days |
| G | Select the party concept | 3 days |
| H | Order the attire | 21 days |
| I | Create a seating chart | 7 days |
| J | Help the couple write their messages to the guests | 7 days |
| K | Decorate the venue | 2 days |
| L | Plan the rehearsal dinner | 7 days |
| M | Party day | 1 day |
*The jobs and durations above are examples. In real life, durations and jobs may vary.
2) Identify Activity Dependencies
A dependency in a project refers to an activity that depends on the completion of another task. For example, for our baby shower party planning work, the number of guests must be known before choosing the venue, as the choice of venue depends on the number of guests. Therefore, it is necessary to prepare the guest list before finding the venue.
In order not to forget dependencies, add an “Immediate Predecessors” column next to the initial list. When writing the antecedent of each task, think about which previous task or tasks need to be finished. Write those tasks in the “Immediate Predecessors” column in the far right column of the table.
| Task ID | Task Description | Task Duration (in Days) | Immediate Predecessors |
| A | Project start | 0 days | |
| B | Find out the couple’s wishes and baby shower party date | 2 days | A |
| C | Write a guest list | 7 days | B |
| D | Book a venue | 7 days | B, C |
| E | Prepare an invitation | 14 days | C, D |
| F | Design and send save-the-dates | 21 days | B, C |
| G | Select the party concept | 3 days | B |
| H | Order the attire | 21 days | B, G |
| I | Create a seating chart | 7 days | C, D |
| J | Help the couple write their messages to the guests | 7 days | B |
| K | Decorate the venue | 2 days | C, B, D |
| L | Plan the rehearsal dinner | 7 days | B, C, E, G, H, I, J |
| M | Party day | 1 day | A-M |
3) Create a Critical Path Diagram
To construct a critical path diagram, begin by representing each task from the dependencies table generated in step two with a corresponding box. Subsequently, demonstrate the dependencies by illustrating arrows connecting each preceding task to its subsequent task(s).
For example, we know that booking the venue (Task ID D) depends on collecting the couple’s preferences (Task ID B) and “creating the guest list” (Task ID C). So tasks B and C are the antecedents of task D. We cannot start task D until tasks B and C are completed. Repeat this process until all tasks and their interdependencies are comprehensively represented in your diagram.
4) Calculate the Duration of Each Activity
Having already determined the duration of each activity, the next step is to ascertain the earliest possible start and end dates for each task. This strategic approach is crucial for scheduling activities to guarantee the timely completion of the entire project, encompassing all tasks. Employ forward pass and backward pass methodologies to compute the earliest start and finish dates for each activity, ensuring comprehensive project management and timely task completion.
Forward Pass
Utilizing the forward pass technique enables you to pinpoint the earliest feasible start and finish times for each activity. This entails establishing the early start time for each task by noting the completion date of the preceding activity. Essentially, the early start time corresponds to the finish time of the previous activity. Subsequently, add the duration of the activity to this recorded time.
Proceed with determining the earliest start and finish dates for each activity iteratively until reaching the final task. The resulting earliest finish date for the last activity within the project denotes the overall earliest completion date or target culmination day for the project.
Backward Pass
In your project timeline, initiate the backward pass by commencing with the final activity and progressively move towards the initial activity. During this process, identify each activity’s latest start and end dates. Employ the subsequent calculation to execute this task effectively.
Late start (LS) = Late finish (LF) – activity duration
For this formula, you need to use the lowest late start (LS) value of the previous activity as the late finish value (LF).
5) Estimate Float Time
Calculating float time in project management is crucial for assessing the flexibility within your schedule. Essentially, it allows you to gauge whether an activity can surpass its estimated duration without causing delays in subsequent tasks or the project’s overall completion. Furthermore, it aids in deciding whether to commence an activity earlier or later, ensuring the timely completion of all project tasks. To ascertain the float time for each activity, employ the following formula:
Slack time = Late start (LS) – Early Start (ES)
6) Calculate the Critical Path
The critical path represents the lengthiest sequence of interdependent activities within a project. While certain tasks may proceed concurrently with this path, they must align seamlessly with critical activities to avoid project delays. Determining the critical path involves identifying activities with zero float time and arranging them sequentially. Another approach involves initiating from the initial task, incorporating all dependent activities, and computing the duration of the lengthiest dependent activity sequence.
Utilize the float times associated with each activity to determine the critical path. Identify and isolate activities with a float time of zero, constituting the critical path. These tasks are pivotal, as any deviation in their scheduling could jeopardize the project’s timeline or quality. Activities with a float time greater than zero must align parallel to critical path tasks.
Determining the critical path can also be achieved by initializing the first activity with a zero start time. Incrementally include subsequent activities that rely on the completion of the initial task, along with their respective durations. This process continues until reaching the final activity in the dependency sequence. The succession of activities with the greatest cumulative duration constitutes the critical path.
Critical Path Method Software
Critical path method software serves as a dynamic tool utilized by both individuals and teams for planning, organizing, executing, and monitoring projects, particularly those of a complex nature involving multiple tasks, dependencies, and timelines. Its primary objective revolves around the elimination of uncertainties through the identification of the critical path, which signifies the sequence of tasks imperative for the successful completion of a project.
Characteristically, this software features a cloud-based architecture, prioritizing heightened security and user-friendliness. It provides users with indispensable features such as Gantt charts and user-friendly calendar views, thereby augmenting project oversight and resource management.
After our research, we have ranked the critical path method software that people like the most. Here are the best critical path software;
1) ClickUp
2) LiquidPlanner
3) Monday.com
4) ProjectManager
5) Lucidchart
6) Quickbase
7) nTask
8) Office Timeline
9) Kanban Zone
10) Zoho Projects
11) MS Project
Videos Related to Critical Path Method
We would like to suggest you a video about the critical path method. You can learn about the critical path method by watching this video. You can click HERE for more videos.