Critical Path Method

CPM (Critical Path Method) is considered as an important project management technique that regulates the existing projects, plans, schedules and undertakes new and complex projects for various industrial processes. The technique helps management in controlling the work of the project. CPM has twofold streams, one for industrial process and the other military.

CPM process of computation was designed for the UNIVAC-I computer. In 1958, it was first tested for the construction of a new chemical plant. CPM is a method to determine the smooth functioning of project management. It uses a definite time for each activity. While CPM is the easiest way to understand and use, it does not consider the time variations that can create a great impact on the critical project to complete within the allotted time. Various worldwide researchers are experimenting to come out with tools which would make their work simpler and enjoyable, without getting stressed by constant rushing against cut-off dates and inefficient operation of resources that one finds on their way.

A CPM chart indicates the critical path in the processes. This may arise when responsibilities are concluded either following or ahead of schedule, impact directly or indirectly the other tasks which may be on stipulated period to fall on the fresh critical path. It is found that PERT/CPM provides a focus around which business managers could come up with and put their ideas together. CPM has been proved to be a great medium of communication which facilitates thinkers and planners at one level to communicate their ideas, their doubts and fears to another level. Moreover, it is playing a significant role in the business process by evaluating the performance of individuals and teams.

The time for critical path is computed by calculating the time taken by the activities in each series and it is the highest path in the given project. It also helps determining the total schedule time necessary for the completion of the project. Outside the critical path is any activity pop up or slow down in the limited time, the total project time remain the same. Duration of an activity especially that is non-critical can be halt or postponed without putting the project in to a pause is known as slack time. The number of times will be computed by considering the time expected for all the activities related. The starting and finishing times of all activities are resolved by working ahead all the way through the chain of work and finding out the initial time when an action can initiate and end considering its predecessor activities. The latest start and finish times are the times when an activity begins and ends without getting the project delayed.

Functioning of CPM in Various Business Processes:

  • Helps in planning and controlling business
  • To determine the possibility of fulfilling particular deadlines
  • Detecting the loopholes in a project
  • Review the impact of changes in the time and requirement of the project
  • Scrutinizing the outcome of projects getting deviated from the schedule
  • Determining the outcome of additional resources to the project

The main purpose of the scheduling stage is to formulate a time schedule depicting the starting and finishing times for the activity and also its relationship to other activities in the project. It gives assurance that the project must be completed within the allotted time to place the project on schedule.

A CPM chart is a visual tool used by the project manager to schedule, organize, and coordinate activities of their project. In every project, a list of project is broken down to be completed in a definite series, which defines the project. Resources are required to complete each task as in terms of money, material, and manpower. The project manager draws out circles or rectangles to represent events – or milestones – in the project. These figures are called Nodes of the CPM chart. The activities which must occur in order to reach a milestone are shown by arrows, and these are known as vectors in PERT/CPM terminology. Nodes are connected by the Vectors, and the sequences of activities are directed by Vectors. Both the Nodes and the Vectors, carrying information, outline the Chart or the Network Diagram.

Benefits of CPM:

  • Project is completed within the allotted time.
  • There is a probability to complete the work before a pre-determined date.
  • The activities of critical path have direct impact on the time of completion.
  • The activities have drooping time and also can let utilize temporarily the resources to the activities of critical path.
  • The date of starting and end of activities.

It is quite obvious for a project manager to get stuck in one single task or activity, or get bogged down with some particular event. There is always the possibility of missing the deadlines. So, to prevent this, one must have to depend on the Critical Path and PERT chart.

PM plays a vital role in six sigma as it helps to solve the problems in a quick and easier way. Six sigma helps to improve the quality of manufacturing processes by identifying and deleting the defects and variation. CPM is a widely accepted mathematical algorithm that is considered to schedule project activities. Different organizations are mounted with various projects which are to be handled at the same time by solving critical process. To complete such projects within the allotted time, a timetable is needed. CPM plays the role of preparing the timetable for the organizations that is necessary for the smooth transaction of business process. With the help of CPM, project managers can be benefited by finding out the exact status of various projects by checking the key events through the CPM timetable.

The basic technique of critical path method is to make a proper schedule for project activities. The effective technique for using CPM is to build a model project that includes:

  • A precise list of activities that is necessary and required to complete the projects or project,
  • The duration that each activity will consume for completion,
  • The dependencies of the activities between them.

Using these available values, CPM calculates the planned activities that are long till the end of the project. It also calculates the latest and earliest with which each activity can start and finish without stretching the project. The main role of the process is to determine the activities that are critical and also which have “total float”. Total float is expressed in no. of days which is a period of time for a particular activity which if delayed would not delay the project. A critical path, in project management refers to the sequence of activities of project network which add up to the longest duration. This determines the possibility of shortest time to finish the project. So, the delay of any activity of the process in critical path impacts directly the designed project and its completion date. A project can have many, near, parallel critical paths. Moreover, non-critical path or sub-critical path plays a significant role and it refers to an additional parallel path through the network which is shorter in total duration than the critical path.

A vital point to be noted is that critical path method considers logical dependencies between the terminal elements. Since then, it allows the addition of resources related to each activity by expanding through the processes termed as resource leveling and activity-based resource assignments. A resource level may also include the delays caused by resource bottlenecks and also may cause a prior shorter path to become the most or longest “resource critical” path. Critical chain is a related notion which attempts to defend activity and project time period from unpredictable delays due to limitation of resource.

Project schedule might change on both regular and irregular basis and thus CPM allows you to monitor the schedule. It also allows project manager to have a status on the critical activities and also alerts the manager of chances that non-critical activities might be waived beyond their total float and as a result creates a fresh critical path and impede the completion of project. Additionally, the method can easily envelop the concepts related to stochastic predictions by using the event chain methodology and PERT (Program Evaluation and Review Technique). In the market, there are plenty of software solutions available that follow or use the CPM method of scheduling.

The CPM has flexibility features. Critical path techniques are often not realized precisely and as a result estimations are applied to calculate duration. If a single mistake occurs, the results of the process of analysis may change. So, it might cause upset if the estimates are blindly believed and also if you do not mention the changes promptly. Moreover, the critical path analysis is such that you can measure the variance from the original schedule caused by any change.

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