Critical Path Method

Analyzing Time within a CPM Schedule

Our life is full of projects, albeit personal. We all are conscious of time and schedules of these projects. It’s difficult to execute anything important without a plan and schedule. Therefore, we always pre-plan and execute the tasks. We make a list, prioritize items, attempt to stick to the time frame, and try to work as per the schedule. On the way, we come across many hurdles and delays, which we try to overcome by supplementing and accelerating other tasks in the process. ‘To-do’ list in our pocket therefore becomes our personal CPM master.

Similar is the case with an organization’s project. Project planners schedule the activities and project managers bring them alive on the ground. On the way, the tasks are monitored, time is analyzed, delays accelerated and project is led to completion on time.

No matter what the project, the sequence of events mentioned here remains constant.  Goal of completing the project on time also remains unchanged. Simply the terminology and the way of executing the plan are different. In place of a ‘to-do’ list we now have the CPM or PERT charts or both. These are now mandatory requirements for any project managers. They have to focus on this chart all the time during the course of the project.

CPM based schedules are the standard project management tools of the businesses nowadays. A well chalked out schedule enables the managers coordinate the project properly. It also helps them to track its progress, monitor and analyze delays or accelerate the lagged behind tasks for completion.

If any of the tasks of the project gets slow, there is every possibility of delay in the completion of the project itself. That increases the expenses of the organization. In this situation, the organization heads demand for an appropriate action to accelerate the project.

CPM and PERT are among the most popular techniques of time analysis in practice today. These tools use charts and graphics to display and monitor the schedules of the project. The methods, in fact, are closely related to each other and point out dependencies and interrelationships between all the activities of the project. These interrelationships between activities form the project network, which allows managers to monitor, analyze and implement the plan for timely completion.

To analyze the time and re-adjust the schedule, the managers need to determine the critical path of the project. It is the longest continuous chain of activities in the project network. The CPM and PERT charts do show the critical path activities that help them to determine a task which is slow or which can complete on time. In the chart, the critical path is always marked in red for easy identification. If a single activity is delayed by, a day or two completion of the entire project may get delayed. By merely glancing at the chart, the managers can identify which activity needs acceleration or which needs support of other task for the timely completion of the project.

Following example may give us better idea of how the time can be analyzed using a CPM schedule. Let’s have a look.

Graphics courtesy: P Coder

The given diagram here is a CPM chart of a project comprising ten tasks. The table after that also gives us a clue to the duration in days of all the tasks and their dependencies in that project. Each task has been assigned the start date as well as end date. The first task is needed to be completed within four days whereas the tenth task is expected to be over before 8 days.

When we analyze the time in this CPM graphics, we come to know that the first task is entirely independent, but the tenth task needs the completion of second task to start the activities. That means if the second task is delayed even by a solitary day, the task no. 10 will get delayed and the project will take another day for its completion. Similar is the case with the tasks 3,4,6,7 and 8. These tasks get underway only when their dependent tasks are completed.

All the dependent tasks in this example are vital and hence cannot be delayed. These are also long duration tasks in the network. The route they form from the starting date of the project to its completion therefore becomes the critical path of the project.

Project managers focus on the activities on these tasks more. They come to know immediately if a task is slow to complete by analyzing its schedule. They can then take appropriate action of supplementing another task to the schedule or adding a few more resources to the slower tasks so as to expedite the process and avoid delay in the completion of the project.

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