Critical Chain Project Management (CCPM) is a more modern approach to scheduling that focuses on resources and buffers, aiming to ensure that projects finish on time, even in the face of uncertainty.
1. Key Concepts of CCPM:
- Critical Chain: The sequence of tasks that considers both dependencies and resource constraints.
- Buffers: Time added to the schedule to account for uncertainties. There are three types:
- Project Buffer: Time added at the end of the project to absorb delays.
- Feeding Buffers: Time added before non-critical tasks to protect the critical chain.
- Resource Buffers: Time added to account for resource availability.
2. Key Formula:
To calculate the total buffer required for the project, use:
- Total Buffer = Project Buffer + Feeding Buffers
3. Example of Critical Chain Scheduling:
Consider a simple project with the following activities, where resource constraints are considered:
- Task A: Duration 4 days, 1 resource
- Task B: Duration 6 days, 2 resources
- Task C: Duration 3 days, 1 resource (dependent on Task A)
For Critical Chain Scheduling, we would:
- Determine the resource constraints (e.g., only one resource is available for Task A and C).
- Apply buffers to account for uncertainties in task durations.
Buffer Calculation Example:
- Project Buffer: You add a 2-day buffer at the end of the project.
- Feeding Buffers: You add a 1-day buffer to Task C to absorb any potential delay from Task A.
This ensures that even if a task is delayed by a few days, the buffer will absorb it, preventing delays to the overall project.
4. Managing Uncertainty with CCPM
The goal of CCPM is to reduce multitasking and focus on the critical chain. By removing unnecessary buffers from individual tasks and instead placing them at strategic points (such as project or feeding buffers), CCPM helps keep the project on track.