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Matvey Belov
Matvey Belov

Critical Chain



Critical chain project management (CCPM) is a method of planning and managing projects that emphasizes the resources (people, equipment, physical space) required to execute project tasks. It was developed by Eliyahu M. Goldratt. It differs from more traditional methods that derive from critical path and PERT algorithms, which emphasize task order and rigid scheduling. A critical chain project network strives to keep resources levelled, and requires that they be flexible in start times.




Critical Chain



Critical chain project management is based on methods and algorithms derived from Theory of Constraints. The idea of CCPM was introduced in 1997 in Eliyahu M. Goldratt's book, Critical Chain. The application of CCPM has been credited with achieving projects 10% to 50% faster and/or cheaper than the traditional methods (i.e., CPM, PERT, Gantt, etc.) developed from 1910 to 1950s.[1]


In a project plan, the critical chain is the sequence of both precedence- and resource-dependent tasks that prevents a project from being completed in a shorter time, given finite resources. If resources are always available in unlimited quantities, then a project's critical chain is identical to its critical path method.


Critical chain project management uses buffer management instead of earned value management to assess the performance of a project. Some project managers feel that the earned value management technique is misleading, because it does not distinguish progress on the project constraint (i.e., on the critical chain) from progress on non-constraints (i.e., on other paths). Event chain methodology can determine the size of the project, feeding, and resource buffers.


A project plan or work breakdown structure (WBS) is created in much the same fashion as with critical path. The plan is worked backward from a completion date with each task starting as late as possible.


Resources are assigned to each task, and the plan is resource leveled, using the aggressive durations. The longest sequence of resource-leveled tasks that lead from beginning to end of the project is then identified as the critical chain. The justification for using the 50% estimates is that half of the tasks will finish early and half will finish late, so that the variance over the course of the project should be zero.[citation needed]


With no slack in the duration of individual tasks, resources are encouraged to focus on the task at hand to complete it and hand it off to the next person or group. The objective here is to eliminate bad multitasking. This is done by providing priority information to all resources. The literature draws an analogy with a relay race. Each element on the project is encouraged to move as quickly as they can: when they are running their "leg" of the project, they should be focused on completing the assigned task as quickly as possible, with minimization of distractions and multitasking. In some case studies, actual batons are reportedly hung by the desks of people when they are working on critical chain tasks so that others know not to interrupt. The goal, here, is to overcome the tendency to delay work or to do extra work when there seems to be time. The CCPM literature contrasts this with "traditional" project management that monitors task start and completion dates. CCPM encourages people to move as quickly as possible, regardless of dates.


Because task duration has been planned at the 50% probability duration, there is pressure on resources to complete critical chain tasks as quickly as possible, overcoming student's syndrome and Parkinson's Law.


According to proponents, monitoring is, in some ways, the greatest advantage of the Critical Chain method. Because individual tasks vary in duration from the 50% estimate, there is no point in trying to force every task to complete "on time;" estimates can never be perfect. Instead, we monitor the buffers created during the planning stage. A fever chart or similar graph can be created and posted to show the consumption of buffer as a function of project completion. If the rate of buffer consumption is low, the project is on target. If the rate of consumption is such that there is likely to be little or no buffer at the end of the project, then corrective actions or recovery plans must be developed to recover the loss. When the buffer consumption rate exceeds some critical value (roughly: the rate where all of the buffer may be expected to be consumed before the end of the project, resulting in late completion), then those alternative plans need to be implemented.


Critical chain project management (CCPM) is a project management methodology that helps you monitor essential resources and prioritize dependent tasks within a project. Learn how to use this framework to help your organization manage resources and complete projects as efficiently as possible.


These two forms of project management are very similar but have one major difference. The critical path method focuses on the single string of concurrent tasks required to complete a project. While other tasks may need to be completed, the critical path highlights all of the tasks that are absolutely necessary for the project's completion. This form of project management can help teams identify the most optimal workflow to create an efficient project timeline. Any tasks that are not part of the critical path are relegated to a lower priority. Project health is dictated by whether or not certain critical tasks are completed by a certain time.


but it also considers the resources needed to complete a project. Because there are so many unknown variables that can contribute to resource constraints, the critical chain method builds resource buffers (excess resources to act as a barrier) into the project timeline. Unlike the critical path method, which only focuses on when tasks are completed, the critical chain method dictates project success by how quickly resource buffers are consumed. If your team hasn't used any resource buffers, your project is progressing successfully.


The feeding chain is a secondary chain of dependent tasks that need to run concurrently with the critical path. Each feeding chain eventually merges with the critical path. This is because the string of events in the feeding chain only affects one of the tasks on the critical path. The feeding chain needs to run at the same time as the critical path to prevent any delays within the critical path.


While these are still steps to the critical path, there are some tasks in a feeding chain that must happen in tandem with the critical path. For example, before sending out party invitations, the team needs to decide who to invite. Before hosting the event, they need to purchase decorations according to the theme, and set up the event. These are all examples of tasks that are in a feeding chain.


Buffers are safeguards built into the resources of the critical chain to ensure a project runs smoothly. Like bumpers in a bowling lane, these buffers are designed to give projects extra wiggle room in the event that something doesn't go according to plan.


Feeding buffers: The extra time that's placed between the feeding chain (also known as the non-critical chain) and the critical chain. Adding this buffer into the timeline prevents any delays from the feeding chain affecting the critical chain.


When you're using the critical chain method, the critical path is the spinal cord of your entire project. It's the entire basis of planning, so figuring out what individual tasks make up that core chain is extremely important.


If you can, estimate how many resources you'll need to complete this project. Estimate how many people it will take to complete a specific task on the critical chain, and approximately how long it will take them. Do this for every task laid out on the critical chain. Based on these calculations, do you have enough resources to complete this project?


Make critical chain scheduling simple by using a work management tool like Asana to help keep your entire team on track. With features like Timeline, team members can quickly get an understanding of task durations, completion dates, and critical resources all in one place.


Identifying the critical path, i.e. what steps must be taken in order to complete a project, will help you to know how to organize your shop, and help you to plan timelines, deliverables, and milestones for your shop.


Critical Chain Project Management (CCPM) is similar to the Critical Path method, in that it strives to identify the critical set of tasks, and the timeline needed to complete a project. However, CCPM takes it one step further, by taking into consideration the resources (people, equipment, physical space, materials) needed to complete the project.


As the progress of the project is reported, the critical chain is recalculated. In fact, monitoring and controlling of the project primarily focused on the utilization of the buffers. As you can see, the critical chain method considers the basic critical path based project network and schedule to derive a completely new schedule.


However, the methodology does not advocate multi-tasking, and in projects with complex schedule networks, the results of implementing the critical path methodology have proven to be a deterrent to the overall project schedule. In addition, there is no standard method for calculating and optimizing the project buffers. The critical path project management methodology has had a fair amount of success in manufacturing; however, it has not achieved any noteworthy success in the IT industry.


Along similar lines, the event chain methodology of project management focuses on determining the uncertain events and the chain reactions they propagate. It is a method of modeling uncertainties and is based on Monte Carlo analysis, Bayesian Belief Network, and other established simulation methodologies. When they occur, events can cause other events, triggering an event chain, which will effectively alter the course of the project. Events and event chains are identified, and quantitative analysis is performed to determine the extent of the uncertainty and the probable impact of the same on the project. From this exercise, critical event chains are derived, which have the potential to impact the project significantly. Event chain diagrams are visual representations of events, event chains, and their impact. 041b061a72