Critical Path Method
The critical path is the list of project milestones you must reach in order to meet the project goal on schedule, together with the mandatory tasks that contribute to each milestone.
Explanation
- The critical path contains the bare minimum number of tasks and milestones to reach the goal.
- Any delay on a critical-path task delays the entire project.
- Non-critical tasks have float (also called slack) — the amount of time you can wait to begin a task before it impacts the schedule.
- Tasks on the critical path have zero float.
How to identify the critical path
- Identify which tasks can happen in parallel vs sequentially
- Determine tasks with a fixed start date
- Determine tasks with an earliest start date
- Identify float for each task
- The longest sequence of dependent tasks with zero float is the critical path
Application
After building the work-breakdown-structure, run critical path analysis to:
- Know which tasks you absolutely cannot let slip
- Identify where buffers should be placed (see below)
- Inform risk planning — single points of failure on the critical path need extra mitigation
Buffers:
- Task buffers — extra time on specific tasks, primarily for tasks outside the team’s control. Use sparingly inside your control; buffering every task unnecessarily lengthens the schedule.
- Project buffers — extra time at the end of the project.
Connections
- work-breakdown-structure
- gantt-chart — typically highlights the critical path
- dependency-types
- risk-management-process
- course-3-project-planning