Critical Path Method
CPM - Critical Path Method
In 1957, DuPont developed a project management method designed to address the challenge of shutting down chemical plants for maintenance and then restarting the plants once the maintenance had been completed. Given the complexity of the process, they developed the Critical Path Method (CPM) for managing such projects.
CPM provides the following benefits:
Provides a graphical view of the project.
Predicts the time required to complete the project.
Shows which activities are critical to maintaining the schedule and which are not.
CPM models the activities and events of a project as a network. Activities are depicted as nodes on the network and events that signify the beginning or ending of activities are depicted as arcs or lines between the nodes. The following is an example of a CPM network diagram:
CPM Diagram
[pic]
Steps in CPM Project Planning
Specify the individual activities.
Determine the sequence of those activities.
Draw a network diagram.
Estimate the completion time for each activity.
Identify the critical path (longest path through the network)
Update the CPM diagram as the project progresses.
1. Specify the Individual Activities
From the work breakdown structure, a listing can be made of all the activities in the project. This listing can be used as the basis for adding sequence and duration information in later steps.
2. Determine the Sequence of the Activities
Some activities are dependent on the completion of others. A listing of the immediate predecessors of each activity is useful for constructing the CPM network diagram.
3. Draw the Network Diagram
Once the activities and their sequencing have been defined, the CPM diagram can be drawn. CPM originally was developed as an activity on node (AON) network, but some project planners prefer to specify the activities on the arcs.
4.Estimate Activity Times
Weeks are a commonly used unit of time for activity
In 1957, DuPont developed a project management method designed to address the challenge of shutting down chemical plants for maintenance and then restarting the plants once the maintenance had been completed. Given the complexity of the process, they developed the Critical Path Method (CPM) for managing such projects.
CPM provides the following benefits:
Provides a graphical view of the project.
Predicts the time required to complete the project.
Shows which activities are critical to maintaining the schedule and which are not.
CPM models the activities and events of a project as a network. Activities are depicted as nodes on the network and events that signify the beginning or ending of activities are depicted as arcs or lines between the nodes. The following is an example of a CPM network diagram:
CPM Diagram
[pic]
Steps in CPM Project Planning
Specify the individual activities.
Determine the sequence of those activities.
Draw a network diagram.
Estimate the completion time for each activity.
Identify the critical path (longest path through the network)
Update the CPM diagram as the project progresses.
1. Specify the Individual Activities
From the work breakdown structure, a listing can be made of all the activities in the project. This listing can be used as the basis for adding sequence and duration information in later steps.
2. Determine the Sequence of the Activities
Some activities are dependent on the completion of others. A listing of the immediate predecessors of each activity is useful for constructing the CPM network diagram.
3. Draw the Network Diagram
Once the activities and their sequencing have been defined, the CPM diagram can be drawn. CPM originally was developed as an activity on node (AON) network, but some project planners prefer to specify the activities on the arcs.
4.Estimate Activity Times
Weeks are a commonly used unit of time for activity