Page 167 - DEDU503_EDUCATIONAL_MANAGEMENT_ENGLISH

Unit 13: Concept of PERT and CPM

13.6 Concept of Critical Path Method (CPM) Notes

CPM is a mathematically ordered network of planning and scheduling project management; it was
first used in 1957 by E.I. du Pont de Nemours & Co. PERT borrows some CPM applications. PERT
proved to be an ideal technique for one-of-a-kind projects, using a time network analysis to manage
personnel, material resources, and financial requirements. The growth of PERT paralleled the rapid
expansion in the defense industry and meteoric developments in the space race. After 1960, all
defense contractors adopted PERT to manage the massive one-time projects associated with the
industry. Smaller businesses, awarded defense related government contracts, found it necessary to
use PERT. At the same time, du Pont developed CPM, which was particularly applied in the
construction industry. In the last 30 years, PERT has spread, as has CPM, as a major technique of
integrated project management.
• Critical path method uses a mathematically-based algorithm in effective project management. The
system helps an individual or organization establish a set of activities and find the best schedule to
finish each task. The critical path method helps a project manager plan which events need to occur
first to complete the whole project when the project has interdependent activities. For example, the
construction of a house calls for plumbing and sheet rocking. The installation of the plumbing needs
to be completed before the sheet rocking can be done. The algorithm in critical path method helps
determine the time it will take to do the plumbing and when to schedule sheet rocking.
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 :

C
1 wk
A F
Start Finish
3 wk 3 wk
D
2 wk

B E
4 wk 2 wk

CPM Diagram

13.7 History

First developed by the U.S. Navy during the 1950s, the critical path method helped project managers
build the submarine fleet. It used a series of time lines that allowed for a timely and decisive program.
The Navy determined when it wanted the project finished and analyzed each step that would need

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