The critical path in project management is the longest sequence of activities that must be finished on time to complete the entire project. It’s a project management technique that involves mapping out key tasks or critical tasks necessary to complete a project. Leveraging this technique allows you to manage task dependencies and set realistic timeframes.
Create a network diagram
Turn the work breakdown structure into a flowchart displaying the chronology of activities
- Create a box for each task and use arrows to depict task dependencies
- Add other time-bound components to the network diagram until you have the general project schedule figured out
Use critical path for better project management
CPM can be a useful asset in project management, particularly for planning tasks and managing resources
Critical path method vs. Gantt chart
CPM: Visualizes critical and non-critical paths and calculates project duration
- Displayed as network diagram with linked boxes
- Doesn’t show resources required
- Plots activities on network diagram without timescale
- GANTT chart: Horizontal bar chart that shows resources required for each activity
- Pairs with CPM to track critical paths over time
Estimate task duration
Make educated guesses based on experience, knowledge, and previous project data
- Estimating based on industry standards
- Forward pass: This is used to calculate early start (ES) and early finish (EF) dates by using a previously specified start date
- Backward pass: Late start (LS) and late finish (LF) dates start with the last scheduled activity and progress backward through the schedule
Calculate the float
Float refers to the amount of flexibility of a given task. It indicates how much flexibility the task can be delayed without impacting subsequent tasks or the project end date.
- Critical tasks have zero float, which means their dates are set. Tasks with positive float numbers belong in the non-critical path.
What is the critical path method (CPM)?
A technique where you identify tasks that are necessary for project completion and determine scheduling flexibilities
- CPM was developed in the late 1950s to resolve the issue of increased costs due to inefficient scheduling
- It helps break down complex projects into individual tasks
Why use the critical path method?
Improves future planning
- Facilitates more effective resource management
- Helps avoid bottlenecks
- Plotting out project dependencies using a network diagram will give you a better idea of which activities can and can’t run in parallel
Identify dependencies
Determine the tasks that are dependent on one another
- This will also help you identify any work that can be done in parallel with other tasks
- The list of dependent tasks is referred to as an activity sequence, which will be used to determine the critical path
Compress schedules
There are two schedule compression techniques you can use: fast tracking and crashing
- Fast tracking
- Look at the critical path to determine activities that can be performed simultaneously
- Crashing
- Allocating more resources to speed up activities
- Before obtaining more resources, make sure it would still be within the scope
Resolve resource shortages
When there is a resource shortage, like an overbooked team member or lack of equipment, you can use resource leveling techniques to solve the issue
Total float vs. free float
Total float: This is the amount of time that an activity can be delayed from the early start date without delaying the project finish date or violating a schedule constraint.
- LS
- ES or LF
- EF
- Free float = ES (next task)
- EF (current task)
- There can only be free float when two or more activities share a common successor (e.g., next task and current task)
Calculating the critical path manually
Write down the start and end time next to each activity
- Look at the end time of the last activity in the sequence to determine the duration of the entire sequence.
- The sequence of activities with the longest duration is the criticalpath.
Compile data for future use
The schedule created from CPM is subject to change since you’re working with educated estimates for activity durations.
Critical path method vs. Project Evaluation and Review Technique (PERT)
PERT is used to estimate uncertainty around project activities by applying a weighted average of optimistic and pessimistic weights
- Probabilistic model, CPM is a deterministic model
- Differences between the two include: list of required tasks, Estimated duration for each task, Task dependencies
List activities
Use a work breakdown structure to list all the project activities or tasks required to produce the deliverables
- The list of activities in this structure serves as the foundation for the rest of the CPM
- Once you have a high-level idea of everything that needs to be done, you can start identifying task dependencies
