Critical Chain Project Management

Three Challenges

• Choosing the right projects

• Getting each one completed more quickly

• Getting more projects done without adding resources

• Critical Chain focuses on the latter two goals

Negative Effects of Trying to Do Too Much

• Multitasking

• Cutting task estimates

• Managing people very closely

Critical Chain Solution

1. Identify the system’s constraint

2. Decide how to exploit the constraint

3. Subordinate everything else to the above decision

4. Elevate the system’s constraint

5. If, in a previous step, the constraint was broken, go to step 1

Critical Chain: Definition

• Longest chain of dependent events where the dependency is either task or resource related.

• Not necessarily equivalent to project duration.

Practices

• Don’t measure on accuracy of estimates

• Don’t measure on meeting deadlines

• “Relay Runner” work ethic

• Allowing new projects to start only when a “strategic resource” is available

• Need to protect projects from task time variations by using buffers

• (22A)

Practices, continued

• Reduce multitasking

• Use multi-project software and make sure the executive, project managers, and resource managers understand it

• Implementation of buffer management as a key process for identifying problems during execution

Task Estimate Example

• Task times are not deterministic, they’re estimates

• Various uncertainty factors

• First task, modifying parts, is relatively easy.

• Last task, testing finished product, is highly variable

• Difficulties are found late in the work.

Example, continued

• “Student Syndrome”

• Skewed curve

• Inflated estimates

• Higher probability of finishing near the estimated duration.

Protection

• Focus on whether project, not tasks, finish on time.

• Deming: Common cause variation: sick time, machines breaking, etc. Take no action.

• Special cause: Things which should be addressed

Control Steps

• Start with best schedule, cut estimates in half, then add half of this back in as buffers.

• Resource-level the project.

• Don’t measure on completing on time or accuracy of estimates.

• Allow people to work on a Critical Chain task in a dedicated manner.

Control Steps, continued

• Change organization’s resource management approach so people can accept work earlier than expected.

• Implement a project buffer (30 to 50% of the critical chain)

• Implement feeding buffers.

Buffer Management

• Examine buffer reports frequently

• These show how far into a buffer a task has taken.

• Look at trends of buffer consumption

Managing Execution

• Set priorities based on which task is most penetrating the project buffer

• Keep data updated frequently, perhaps daily

• Negative effects of multitasking

• Strategic resource buffer

• “Drum” resource is the one most likely to impact the cycle time of all projects