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How to Succeed (or Fail) in Implementing Critical Chain Project Management

There are several examples of successful implementation of the Critical Chain, but there are also numerous examples of failed attempts. We can learn more from the failed attempts than from the successful ones, and maybe deduct a few “things to avoid.”

A Short Introduction to What the Critical Chain Is

Critical Chain Project Manager (CCPM) is a methodology of project management derived from the Theory of Constraints (TOC). It has been described in the book “Critical Chain” written by Eli Goldratt.

CCPM aggregate the protection against variations in the performances of the tasks into a buffer of time placed immediately before the deadline delivery date.

In the same time, it reduces the time for each task and gives them only 50% of chance to be performed in time.

It also introduces the notion of feeding buffers as buffers of time in the branch of the contract feeding the critical chain.

The critical chain is defined as the longest path of resources and tasks dependencies.

CCPM also introduces the resource buffer, which is a communication buffer. The next resource working on the project is informed that the previous task shall be finished soon and that she needs to get ready.

Define the System

CCPM is not a magic wand. It will be performing extremely well in what it has been designed for. Try to take a forest track with a Formula One car, and you will be disappointed.

CCPM is a project management methodology, so it should be applied to individual projects not to a flow of projects.

Flows of projects present some specific issues that need specific solutions. CCPM doesn’t provide these solutions.

The first error is using CCPM for what it is not.

The optimization of each project duration by using CCPM on each one will not automatically result into an optimized project flow. There is more in project flow management. There are TOC solutions for that, by example synchronous projects flow.

Review the Basic Hypotheses of CCPM

CCPM has a set of basic hypotheses that give context to its validity, like all methodologies.

CCPM needs that the following criteria are met:

• A breakdown of the project into tasks has been made (a WBS — work breakdown structure).
• The dependencies between the tasks are clear;
• The list of resources used to perform the project is clear (an RBS — resource breakdown structure)
• The allocation of resources to task is clear;
• And most importantly the contentions of resources have been solved.

Do you remember the definition of the critical chain?

The longest path of resources and tasks dependencies.

This means that all the dependencies between resources have been clarified when determining the critical chain.

The critical chain is not a critical path with a buffer at the end.

Critical Chain

Immediate Consequences

These hypotheses have direct and immediate consequences, that need to be fully understood to be able to apply CCPM efficiently.

1. The resource shall be free to focus on the task at hand. The system has been defined as the project, so the resources shall be free from disruption coming from outside the project as far as possible. This is the role of the project managers to protect their resources. Not offering this protection is making sure that all tasks will finish late and that the time buffer will be consumed immediately.
2. The critical chain is a relay race. Each resource having their task at hand shall work it as fast as possible and inform the following resource that they are getting close to deliver. This is the way you can benefit from the positive effects.
3. The management shall remember that team members have 50% of delivering on time their task. This means that they also have 50% of chance of NOT delivering in time. This was done to release the padding usually included in each task estimate and create the time buffer. As there is this time buffer, finishing a task late has no impact on the project delivery date. But if people are blamed when they are late, or if their performances are evaluated based on the due date compliance of each individual task, then they will add padding to their task estimate for the next project and most importantly will distrust their management.

Usual Padding of Tasks

Main Consequences and Benefits

If you do it well. You release resource contentions to create the critical chain, you protect the focus of your team during execution, you don’t blame people delivering after their estimate, your team acts as a relay race team. Then you will harvest the benefits of CCPM.

1. You will shorten your lead times by 25% (half of the padding released from the individual tasks) and this benefit shall even increase when the team gets more used to this methodology;
2. As your final delivery date is protected by the project time buffer, the delivery date become much more reliable. It is usual to see an improvement in due date compliancy of 60% or above.
3. The Critical Chain doesn’t change during a project execution. Those who already have seen the critical path changing day after day shall understand how important this is. The focus of the project team will remain constant and will allow a much less stressful management.
4. The time buffer is the main indicator of health of your project. It allows to see the evolution in a fever chart and to trigger corrective action in due time and not too often. The corrective action is triggered by the status of the project, not by the status of individual tasks. This reduces the need for expediting dramatically.

Reduction of lead time by CCPM

Main Causes of Failure

So, what are the main causes of failure?

• Use CCPM for what it is not: an optimization methodology for project flows;
• Add a time buffer to a critical path and call it critical chain
• Don’t resolve all resource contention while determining the critical chain
• Don’t understanding the goal of the critical chain. CCPM will not protect the projects from the perturbations of resources. It will protect the delivery date against variations of performances of resources that have no contention.
• Evaluate people on individual task performance, losing sight that a task performed doesn’t get you closer to the goal of your company, only getting the whole project finished shall get you closer to your goal.
• Expedite when a task is late. The buffer is there to protect the only thing that counts, the delivery date. Expedite when unnecessary only brings chaos.
• Allowing exterior perturbations of the resource working on a task of the critical chain.
• Promoting multitasking

Conclusion

Critical Chain project management is a powerful methodology which delivers strong results. But it needs to be used for what it has been designed for. Like all the project management methodologies, it needs discipline.

In too many cases, the designated project manager does not have the necessary training. Being a Project Manager is a hard job and is not for the faint hearts. It requires training and experience.

I would not say that CCPM is better than Waterfall or Agile or Scrum. I would say that applied correctly by people understanding the necessary context it gives wonderful results, but the collateral consequence is that when badly applied it may damage the execution of the project.

The issue is not what methodology you choose to apply. They are no magic wands. The issue is how you apply the methodology you have chosen.

Didier Varlot is a project manager with 35 years experience in project recovery and 25 years of application of the Theory of Constraints. He uses a mix of Theory of Constraints, Agile and Open organization (the TAO Way) to improve operations in every industry. He is one of the authors in the Virtuous Circle: Thinking logical and has his own publication on medium.

You can follow him also on Twitter.