What is a Critical Path Method (CPM)?
→ The Critical Path Method is used to determine the shortest possible time to complete the project.
→ The CPM is a sequence of activities of a project's starting activity & time and the project's finish time and activity.
→ This tool is totally based on mathematical calculations and is used for scheduling project activities.
→ The CPM was developed by James E. Kelley and Morgan R. Walker in the 1950s.
→ Initially, the CPM_Method was used for managing plant maintenance projects.
→ CPM_method is used for planning and scheduling activity.
→ This_method also shows the interrelationship between the_time and cost of the_project.
→ Critical_Path_Method helps us to assess the different possibilities of project planning.
→ This method is one of the parts of the Arrow Diagram.
→ Refer to this article for fundamental of Arrow Diagram/Critical_Path_Method_Basics
👉 Download Critical Path Method with Example PDF File
Where CPM Method is used?
→ CPM_Method is used in the below fields
- Software Development
- Construction
- Aerospace & Defence
- Research Projects
- Product Development and many more fields
Critical Path Method Example
→ Refer to the below example for understanding how to identify the critical path in project management.
→ We will follow the below five steps for understanding the CPM_Method.
→ For calculation, we will refer to the activity from A to K, completion time duration, and the immediate predecessors as mentioned in 1st step.
What are the steps in CPM?
→ There are five steps in the CPM_Method as mentioned below.
- Step_1: List Out the Activity
- Step_2: Forward Pass Calculation
- Step_3: Backward Pass Calculation
- Step_4: Float Calculation for Each Activity
- Step_5: Identifying the Critical_Path
Step 1: List Out the Activity
→ First of all, we will list out all_activity, their immediate predecessors, and completion time.
→ For this refer to the below table.
→ Now with the help of the above table, we will simplify and arrange all_activity and time with the critical path method.
→ In this example, A,B,C,D,E,F,G,H,I,J, and K are representing the activities.
Step 2: Forward Pass Calculation
→ In the forward pass, we calculate the Starting durations of all the activities.
→ So we can easily show the calculations from the below picture.
→ It starts from the first_activity and after that, we will add the time period as per the_activity.
→ By repeating this process we will get the final time of the end of all_activity with the different paths.
Step 3: Backward Pass Calculation
→ Now, in the third step, we will calculate the backward pass.
→ In the backward pass calculation, we will take the end activities time as start_time as a finish_time.
→ In this example, it is 24.
→ The backward pass is processed by subtracting the duration of the activities leading to the end_activity node.
→ By repeating this process we will arrive at the finish_time which means at the beginning.
Step 4: Float Calculation for Each Activity
→ Now the fourth step is to calculate the float of each_activity.
→ The float is the simple difference between the backward pass count and the forward pass count.
→ We can easily see the float value for all activities from the below picture.
Step 5: Identifying the Critical_Path
→ Now the final step is to identify the critical_path out of all different possible paths.
→ The critical_path is the longest path in the network diagram.
→ The total float of the critical_path is zero.
→ It is shown as light red color in the below picture.
Advantages of CPM Method:
→ This tool is used for planning, scheduling, monitoring, and controlling various types of projects.
→ It helps us for proper communications between departments and functions.
→ We can estimate the expected project completion date.
→ This tool is very easy to use.
→ We can identify the critical path with the help of this tool.
→ It is very useful in monitoring costs
→ This tool is visually very effective so all people can easily understand.
→ We can also reduce the project completion timelines by using this method.
→ CPM Method improves the decision-making ability of the team.
→ By using this tool we can able to determine which activities can be delayed without delaying the project
Disadvantages of CPM Method:
→ The reliability of this tool is based on accurate estimates and assumptions.
→ This tool does not give surety of the success of the project.
→ If we have many activities then our network diagram will also be complicated.
→ The estimate of activity timing is subjective and depends on the judgment.
Limitations of the Critical Path Method:
→ This method is not feasible for large and complex problems. We need to use software for this.
→ We can not able to allocate resources by this method.
→ If activity durations are determined wrong then the critical path of the project will be wrong.
→ If there are many other similar duration paths available in the project at that_time it is very critical to identify the Critical Path of the project.
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