Critical chain project management made simple
Imagine opening your to-do list for the day and realising that you need to be able to multitask in order to get everything done. But that's impossible, because how can you manage two different tasks at the same time? This is where critical chain project management (CCPM) comes in. This is a project management method invented and developed by Eliyahu M. Goldratt. The aim of the method is to create a more realistic project plan by including existing resources in the planning.
What is critical chain project management?
In critical chain project management, the resources allocated to the packages are planned from the outset, along with the corresponding work packages. CCPM takes the principles of project management and adds two main aspects. The first is resource planning, which focuses on avoiding multitasking. The second is time estimation for each work package, which is done in such a way that no time reserves are built into the work packages. There is only a buffer for important milestones and at the end. A path is also created during planning. The longest path in which the work packages are lined up with the associated resources is known as the critical chain.
Let's look at an example with five work packages. While many project managers plan work package 1 plus buffer, then work package 2 plus buffer, then work package 3 plus buffer and so on, CCPM takes the most optimistic approach. This means that the five work packages are sequenced so that the most optimistic duration is assumed and a single buffer is added at the end, after the fifth work package has been completed. However, when a project has significantly more than five work packages, there are sometimes milestones with corresponding buffers in between.
In general, Eliyahu M. Goldratt's goal has always been to complete a project not only on time but, if possible, ahead of schedule.
Critical Path and Critical Chain
A few words on the difference between the critical path and the critical chain, as there is often confusion due to their close conceptual relationship. The critical path is the longest sequence of tasks in the overall project schedule and therefore determines the minimum duration of the project. If one of the work packages is delayed, the whole schedule is affected. However, it is common to include a small buffer for each task and to allow for multitasking.
The critical chain builds on this critical path, but optimises it, taking into account resources, so that the tasks on the critical path are processed as quickly as possible and are lined up without a buffer. As mentioned at the beginning, multitasking is not allowed in critical chain management and buffers only exist for specific milestones.
CCPM and TOC
A unique feature of CCPM is the emphasis placed on ensuring that each project team member is 100 % committed to the project at all times. This ensures that all projects are completed as quickly as possible. Project progress must be assessed on a daily basis so that corrective action can be taken immediately. If these methods are strictly adhered to, it is often possible to complete a project on time or even ahead of schedule. This is based on TOC, the Theory of Constraints or bottleneck theory. This is a method for improving project flow. In bottleneck theory, a weak point is called a bottleneck. Each bottleneck slows down the flow and the goal of the project manager is to remove all bottlenecks.
The development of TOC dates back to 1979, when five steps were initially developed to eliminate bottlenecks:
1. Identify the bottlenecks
This could be a time-consuming process, an inhibiting person or a critical process. Identification also makes it possible to analyse the impact on project duration.
2. Maximise the use of the bottleneck
This avoids additional investment and eliminates the bottleneck as a limiting factor.
3. Align everything around the bottleneck
Only when all elements of the project contribute to the solution can the biggest bottleneck be removed.
4. Eliminate the bottleneck
If the bottleneck has not already been removed, it should be removed here, even if it requires additional resources.
If this point is reached, the main problem should be solved. If not, the process can be repeated.
Anyone presenting a critical chain project schedule to a customer must be aware that this is optimistic planning. Optimisation must therefore be planned carefully, taking into account all resources, and the availability of these resources is a crucial aspect. With this type of planning, the process is very efficient, but as soon as someone is absent due to illness, this optimistic planning becomes a problem. So you have to think carefully about what kind of planning you want and then present it to the customer.
Engineers and managers who consistently apply and implement critical chain (and who can consistently complete projects exactly according to the critical chain plan) have found that they can save 25 % of the time compared to conventional planning. However, it is important to build in buffers at the milestones and at the end of the project. It is important to monitor the buffers and measure buffer usage during the project.
Keywords: Project management, Critical chain