Critical Path is the sequential activities from start to the end of a project. Although many projects have only one critical path, some projects may have more than one critical paths depending on the flow logic used in project.
In the critical path method, the critical activities of a program or a project are identified. These are the activities that have a direct impact on the completion date of the project.
In the critical path method, the critical activities of a program or a project are identified. These are the activities that have a direct impact on the completion date of the project.
Steps in CPM project plannning
1) Specify the individual activity - only the higher level activities are selected for critical path method. When detailed activities are used, the CPM may become too complex to manage and maintain.
2) Determine the sequence of those activities - For that you need to ask three questions for each task of your list.
a) which task should take place before this task happens
b) which tasks should be completed at the same time as this task
c) which tasks should happen immediately after this task
3) Draw a network diagram - once the activity sequence is correctly identified, the network diagram can be drawn.
4) Estimate the completion time for each activity
5) Identify the critical path - for this you need to determine four parameters of each activity
- Earliest Start Time (EST)- the earliest time an activity can start once the precious dependent activities are over.
- Earliest finish time (EF)- ES + activity duration
- Latest finish time (LF)- the lates time an activity can finish without delaying the project
- Latest start time (LS)- LF - activity duration
6) update the critical path diagram as the project progress
Benifits-
- provides a graphical view of the project
- predicts the time requested to complete the project
- shows which activities are critical to maintaining the schedule and which are not.
Limitations-
CPM was developed for complex but fairly routine projects with minimal uncertainty in the project completion times. For less routine projects there is more uncertainty in the completion times, and this uncertainty limits the usefulness of the deterministic CPM is PERT project planning model, which allows a range of duration to be specified for each activity.