The Origins of CPM, PDM and PERT Schedules

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Location:  PMKI > PM History > Origins of CPM, PDM and PERT 
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This subject looks at the origins of the CPM, PDM and PERT network diagramming techniques and calculations.

Topics included in the Origins of CPM, PDM and PERT Schedules

- Origins of CPM (Critical Path Method and AoA)
- Origins of PDM (Precedence Diagramming Method and AoN)
- Origins and limitations of PERT

Other related sections of the PMKI:

- The history of project controls
- The history of project management
- TBA
- TBA
 
 
 


Origins of CPM (Critical Path Method and AoA)


Art: Critical-Path Planning and Scheduling. 
James E. Kelly Jr., Morgan R. Walker, Proceedings of the Eastern Joint Computer Conference (USA), 1959. This paper defines the original concepts and calculations used in CPM scheduling. Both CPM and PERT used ADM (Activity-on-Arrow) networks and were developed as mainframe computer applications. 

PP: The Origins of CPM, A Personal History.  An in-depth interview in the first person, Kelley J.E. Jr and Walker M.R. pmNetwork Vol III, No. 2, Feb 1989.  PMI, USA.

Art: The Origins of Hammocks and Ladders. Hammock and Ladders are activity types that were developed in the period 1961 to 1965. This paper outlines the development of these useful scheduling assets an differentiates Hammocks from LOE and Summary activities.
 
 

Origins of PDM (Precedence Diagramming Method and AoN)

Art: A non-computer approach to the critical path method for the construction industry (2nd Ed.). John W Fondahl,  Stanford, Calif., Dept. of Civil Engineering, Stanford University, 1962. This paper defines the original concepts that lead to the development of the dominant PDM methodology of scheduling we use today. 

PPPrecedence diagramming methods origins and early development.  An in-depth interview in the first person, Fondahl, John W.. pmNetwork June 1987.  PMI, USA.

Art: Process Charts: First Steps in Finding the One Best Way to do Work. 
Frank & Lillian Gilbreth (1921). This paper defines the original concepts used to create process charts, the forerunner to the flow charts we use today and the basis of PDM networks. 

 
 

Origins and limitations of PERT


WP: Understanding PERT: This White Paper defines PERT describes its development and clearly delineates the major flaws in its design.

Art: Application of a Technique for Research and Development Program Evaluation: This is the original 1959 paper by D.G. Malcolm, J.H. Roseboom, C.E. Clark, and W. Fazar; defining the PERT calculations, their development and their limitations.

Art: Where did the Misuse of the names Gantt and PERT Originate?  This article traces the rise in the misuse of the term PERT associated with the incorrect designation of a Precedence Diagram in Microsoft Project as a ‘PERT Chart’.

PERT/Cost was a 1962 development of PERT (time) that preceded the introduction of Earned Value. See the: 1964 Evaluation of PERT/Cost.

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