The Critical Path Method (CPM) is a handy technique to monitor an ongoing project. It involves various tasks and activities in a human network with proper scheduling in the form of graphical chart. The tasks involve work activities. Most often than not, these are dependent upon each other to start or complete by the prescribed date. According to the University of the Sunshine Coast document, CPM “recognizes the interdependency of activities. Specifically the fact that some activities must be completed in a particular order.”
No doubt, the critical path method highlights dependent relationship between the tasks and activities of the ongoing project.
Because of this dependency, the CPM helps the project managers to monitor and track the progress of the ongoing activities, supplement or remove resources and, if delayed, speed up the processes.
Therefore, to design a CPM chart, managers need a list of tasks, formulate their dependencies and form the project schedule. The following diagram shows the interdependency between the tasks of a project.
CPM TASKS INTERDEPENDANT ACTIVITIES
A task or an activity has a set of actions with start and finish dates, which forms the part of project duration. Project requires many tasks to complete. Their performance time may not be the same and may sometimes run independently. Many a time, an activity is entirely dependent on the completion of other or its predecessor tasks.
The amount of time required to complete these tasks is calculated in hours, weeks, days or weeks. The task itself is represented in alphabetical form in circles or squares in the CPM chart. Sum total of this duration becomes the duration of the project. For instance, a four week duration project involving renovation of a big building has following task duration:
Task Activity Duration
01 (A) Wall coloring 03 week
02 (B) Wall framing 04 week
03 (C) Electric fittings 01 week
04 (D) Plumbing activity 02 weeks
05 (E) Flooring 02 weeks
06 (F) Finishing and Furniture 03 weeks
These tasks have their start and end date and show interdependent relationships as represented in the following activity network diagram.
In the given chart, it becomes clear that the activity numbered C and D cannot be started unless the first activity A is completed. That means C and D are entirely dependent upon their predecessor task which is A. It also means that if the task A is delayed even by a day or two the C and D will take that much of time for completion. In such a case, there is a danger of delaying the entire project. Therefore, the project managers have to be meticulous over the early start and early finish of activity A, in this case. CPM therefore shows dependent relationship between the tasks of the project.
Project Managers therefore plan for and manage the dependencies among tasks in their projects as exemplified above. Dependencies between tasks show related individual activities. Progress of the project depends upon this relationship.
CPM TASKS CRITICAL PATH
The dependent relationship also leads to the identification of critical path of the project. Project managers require to form the project schedule by estimating the start and end date of each task. All such interdependent tasks formulate a path known as critical path of the project. These tasks therefore become critical tasks. If a critical task is delayed by hours or days or weeks, the other dependent task/s also get delayed. The entire project, therefore, faces delay by that many hours or days or weeks. Because of that, the project managers needed to focus more on the critical path tasks and supplement additional resources to accelerate the activity in case of such a delay.
Thus, the project dependencies establish links and form working relationship between all the tasks of the project. That makes the schedule of the CPM project to expand or collapse as linked tasks are executed in the network.