Critical chain method
|Critical chain method|
Critical chain method - CCPM (Critical Project Chain Management, Critical Chain Method) - this is a method of planning and project management, which mainly focuses on the resources needed to complete a given project. This method was developed and developed by the Israeli physicist Dr. E. Goldold in 1977 in the book "Critical Chain". This method is one of the most important tools of the Theory of Constraints. CCPM is not targeted as opposed to more traditional methods for planning or maintaining the order of assigned tasks. The purpose of this method is to keep resources on an equal level so that the project can be carried out in accordance with the planned schedule.
It is believed that using the critical chain method, the project can be carried out 10-50% faster and reduce its cost by the same value than the traditional methods that were used at the beginning of the 20th century (CPM, Gantt Diagram, PERT). The research shows that the application of the CCPM method guarantees compliance of 95% completion of projects in terms of timeliness and budget allocation, where, in the case of traditional methods, this is only 44%.
When implementing projects using the traditional method, as much as 30% of the lost time and resources allocated for this purpose are caused by the lack of prioritization or multitasking. A string of connected, longest activities that are necessary to carry out a given project is called a critical chain. The critical chain is used as another possibility to analyze the critical path. Features that differ the critical chain from the critical path are:
- Taking into account dependencies between resources, which are very often hidden, i.e. not included in the project's network
- Not looking for the best solutions, but determining those seemingly good (optimal) for the project
- Pointing and entering buffers
- Consumption rate control to check the progress of project work
When developing a project plan, time is taken into account that is necessary to perform a specific task together with a safety margin. Using the critical chain method, the periods with safety reserves are summed up and the so-called buffers that are intended to protect the timely completion of the project. CCPM is not aimed at managing the positive value, because in the opinion of people in a managerial position, there is no difference between the progress in the critical chain and the progress on other paths.
In the critical chain method, the plan created for the project and the distribution of duties is created in a similar way to the critical path. They are arranged starting from the end and then we are going backwards, so that each analyzed task start as late as possible. In this way, buffers are created.
- project buffer - located at the end of the planned schedule (critical path). It is an element whose aim is to ensure safety to complete the project in accordance with the previously provided date.
- Feed buffer - this is the link of the schedule, whose main task is to ensure invariance and stability of the critical chain. It is at the end of the non-critical path in the schedule, which then reaches the critical path.
When the project plan is completed and the project is ready to start, the buffer sizes are "closed". This means that their expected duration can not be modified during the project, as they will be indicators used to control the plan and financial results of the project. To eliminate multitasking and prevent downtime, resources are focused on the task which is closest, so that the case will be forwarded to the next designated persons. In practice, the use of CCPM can be found with examples of people who, while working on their part of the project, inform others not to interfere with them by hanging relay sticks. An important issue is also to combat the tendency to delay or do extra-leisure work in your spare time. The critical chain method encourages those involved in the project to act as quickly as possible, regardless of the dates provided.
The benefits of using CCPM
The benefits that result from the use of the critical chain method are:
- Eliminating conflicts when allocating resources
- Consistent and systematic time management, which was saved during the implementation of individual tasks (Relay Effect)
- Striving to completely overcome the overestimation of task times
- Eliminating the so-called Student's Syndrome - implementation of planned projects for the last moment
- The use of Murphy's Law by using buffers
- Reducing multitasking
- Improving the control of project implementation
Features of the Critical Chain Method
The critical chain method has the following characteristics:
- The most important thing is to complete the entire project within the prescribed period, and not the timeliness of individual tasks,
- The time security margin needed to implement the project cumulated in buffers
- Assigning partial tasks to specific people - eliminating multitasking
- The smallest unit of time used in the project plan is 1 business day
- Placing anticipated time needs to implement the project in reports
- Management of management personnel focused on critical tasks
- Using the percentage of buffer usage as the main indicator
CCPM methods to eliminate the causes of delays
Using CCPM, we can overcome the causes of delays by:
- Planning the order of performing tasks - queuing (Pareto rule)
- Starting tasks as late as possible so as not to bind resources
- Using buffers that allow planned completion of the project
- Management focused on achieving the goal
- Herroelen, W., & Leus, R. (2001). On the merits and pitfalls of critical chain scheduling. Journal of operations management, 19(5), 559-577.