The critical path method (CPM) is a sophisticated project management technique for planning, scheduling, and managing the tasks necessary to complete a project from start to finish. It is also sometimes referred to as critical path analysis (CPA).
Any team in any industry can use critical path methodology to manage complex projects. What’s more, a good project management software platform will be able to take the CPM data of a project and turn it into a visual representation, displaying the tasks, their dependencies, and the critical path to make it easy to understand and manage the project at a glance.
In this article, we’ll tell you everything you need to know about the critical path method, and answer questions such as:
We’ll also show how Wrike’s project scheduling template and Gantt chart software will help you visualize and manage your project’s critical path.
For project managers, keeping initiatives on schedule and within budget is imperative. The critical path method (CPM) is an essential project management technique for planning tasks efficiently. Learning how to develop and leverage a critical path can help you deliver projects successfully.
In this comprehensive guide we’ll cover what a critical path is its key benefits, and tips for creating one for your next project.
What is a Critical Path?
The critical path refers to the longest sequence of dependent activities in a project plan that must be completed on time for the project to meet its deadline. It determines the minimum amount of time needed to complete a project
Activities on the critical path have no slack or float time. Any delays in critical tasks will impact the planned project completion date. By understanding the critical path, project managers can identify which activities are critical to keep projects on schedule.
Benefits of Using the Critical Path Method
There are several key advantages to using the critical path method for project scheduling:
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Forecasts the shortest project duration – Creating a network diagram and critical path determines the minimum amount of time needed to complete the project.
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Identifies critical activities – The critical path highlights which specific tasks have the potential to delay the project if they fall behind schedule.
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Provides priorities – By seeing which activities have float, project managers know which tasks have scheduling flexibility and which must be started and completed as planned.
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Identifies risks – The critical path helps determine where schedule problems may arise so proactive risk management can be applied.
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Optimizes resource planning – Knowing which activities are critical and non-critical helps optimize task resource allocation.
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Enables compression techniques – Where possible, tasks on the critical path can be compressed by adding resources to reduce durations.
Overall, the critical path method provides an invaluable roadmap for keeping projects on track to meet planned deadlines.
How to Create a Critical Path
Identifying the critical path involves several steps:
List All Project Activities
First, list out all the activities or tasks needed to create the project deliverables. The goal is to create a comprehensive work breakdown structure. Activities can be broken down into categories like:
- Start-up tasks
- Design phase
- Content creation
- Development and testing
- Review cycles
- Final approvals
Capture all activities, even small ones like obtain sign-off or send notification emails. Every task impacts the schedule.
Determine Dependencies
Next, sequence the tasks in order of progression and determine dependencies. Some examples:
- Task B can’t start until Task A is finished.
- Task C and D can run simultaneously after Task B is done.
- Task E relies on both Task C and D being complete.
Understanding interdependencies is crucial for network diagramming and calculating the critical path.
Draw a Network Diagram
With the activity sequence defined, create a project network diagram. The most common approach is using Activity on Node (AON):
- List activities in nodes on chart
- Connect dependent tasks with arrows indicating flow
- Capture estimated duration in each node
The network diagram visually maps the workflows and dependencies needed to progress through the project.
Estimate Task Duration
As you build the network diagram, estimate how long each task will take to complete. Several techniques can be used:
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Expert judgment – Consult specialists in each area to estimate realistic durations based on experience.
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Historical data – Refer to durations from old project records for similar tasks.
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Three-point estimates – Create best case, worst case, most likely estimates to gauge range.
Identify risks that could cause delays during estimation. Build in contingency with padding or buffers.
Determine the Critical Path
The critical path is the longest full sequence of dependent activities through the network diagram. To find it:
- Calculate duration for each path by totaling task estimates
- The path with the longest duration is the critical path
If multiple paths tie for longest, they are all critical paths. The project can’t finish until all activities on the critical path are complete.
Calculate Float
Float, or slack time, is the amount of time an activity can be delayed without affecting the overall project finish date. To determine float for each path:
- Take the total project duration
- Subtract the duration of that path
- The difference is the float time
Float is calculated as a buffer for activities with scheduling flexibility. Critical path tasks will have zero float.
With the critical path marked on the network diagram, the project team can clearly see the key sequence of activities that determines the project timeline.
Tips for Managing the Critical Path
Once you’ve created the critical path schedule, keep it on track with these tips:
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Prioritize critical activities – Focus resources on starting and completing critical path tasks as planned.
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Monitor closely – Closely track progress on critical path activities to quickly address any delays.
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Compress the schedule – Shorten durations of critical tasks by adding resources or working overtime.
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Manage risks – Have contingency plans to counter risks that could impact critical path tasks.
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Update estimates – As the project progresses, update task estimates and the critical path accordingly.
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Consider trade-offs – Evaluate using float from non-critical tasks to get ahead on critical ones.
Proactively managing the critical path is key to keeping projects on schedule and preventing costly delays.
The critical path method is an essential technique for project managers to master. Creating a critical path network diagram provides a roadmap to optimize the schedule. Identifying the chain of critical activities enables the project team to focus on priority tasks that directly impact the timeline. Monitoring and managing the critical path is crucial for delivering projects successfully and on budget. Use these tips to leverage critical path analysis and keep your projects running smoothly.
Step 3: Estimate the duration of each task
Assign a time estimate to each task. This should be the total time required to complete each task from start to finish. Make sure to account for any potential delays or issues that may arise by incorporating buffers or contingency time into your estimates.
Two techniques that can help project managers accurately determine each task’s duration are the forward and backward pass techniques:
- Forward pass: Starting from the beginning of the project and moving forward through the critical path diagram, calculate the earliest start time and finish time for each activity. This helps determine the earliest possible project completion date for the entire project.
- Backward pass: Work your way backward from the project’s end date through the CPM chart, calculating the latest start time and finish time for each activity. This helps identify the latest possible project completion date for the project and determines the amount of scheduling flexibility or slack time available for each activity.
Adjust to changes in the critical path
Let’s assume that choosing the curtains took our friend longer than we initially expected. This will delay the end of the project.
Our redecoration is incomplete without the new curtains, so the path that previously was non-critical becomes critical. The initial critical path changes.
To monitor your non-critical tasks, your project schedule must be current. That’s the only way you’ll know exactly where your project is at any given moment and whether it will be delivered as initially planned.
Project Scheduling – PERT/CPM | Finding Critical Path
What is a critical path in CPM?
CPM Examples How To Find The Critical Path How To Calculate The Critical Path The critical path of a project is the longest path between project start and project end, and the critical path method is the technique used to determine that path.
What is the critical path method?
The Critical Path Method is ideal for complex projects that have a lot of moving parts. By breaking a big project into smaller, more manageable tasks project managers can gain a better understanding of how to get from point A – Z in the most efficient way. Critical path finds its origins in the 1950s at the DuPont company.
Why should project managers use the critical path method?
The critical path method offers project managers the ability to stay on budget more easily, schedule talent and resources efficiently, monitor progress, not get overwhelmed with project management demands, monitor and report on project progress and keep scope creep in check.
How do I find the critical path of a project?
Using our critical path example, this includes tasks 3, 5, and 10. To determine the LS of these earlier tasks, simply subtract their duration from task 11’s LF. If a task points to more than one other task, use the lower LS as that task’s LF. In order to find the project’s critical path, follow the tasks that have the same EF and LF.
