CCM (Critical Chain Method) is the above-standard network analysis technique, which follows the Critical Path Method (CPM) and also includes accessibility and availability of resources. E. M. Goldratt is the author of this method, as well as of the Theory of Constraints, from which it is based. Its aim is to determine the duration of the project based on the length of the critical chain, which is a sequence of interdependent activities with the shortest time advance, which in addition takes into account the constraints of resources and shifts part of the implicit reserves of activities into so called buffer activities. The concept of critical chain is replaced by the critical path from the CPM. Critical Chain Method allows to facilitate the effective time coordination of a individual, mutually following activities within the project, including planning of resources needed.
This method therefore combines the CPM method and theory of constraints TOC that perceives resources as shared with capacity constraints and provides the calculated time with certain reserves. Therefore it improves the result by eliminating the shortcomings of methods CPM or PERT.
Critical chain is defined as the (time) longest possible path from start point to final point of the chart that takes into account the capacity constraints of the resources. Each project has at least one critical chain. Each critical chain consists of a list of activities on that the project manager should focus most, if he wants to ensure timely completion of the project. The date of completion of the last task in the critical chain is also the date of completion of the project. For critical tasks it is applied that their total reserve time and therefore free time reserve is equal to zero, i.e. that delay of this task or extend of its duration will affect the final date of the project. Critical chain is reflected in the time planning and project management in virtually all phases of the project life cycle.
Use of the Critical Chain Method: This method can serve as a tool for estimating the duration of the project. It is used as an alternative to CPM . From the method is derived a branch of project management called Critical Chain Project Management (CCPM). In particular, CCM method is used within the project management and in the field of logistics and transportation.
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