Critical path method (CPM) was developed in USA in 1957 by Morgann E. Walker and James Kelley. This method was first used for planning and scheduling the construction of a new chemical plant by DU pont. Later this method was used for scheduling the overhaul and maintenance for shut down of equipment I their works.
CPM networks are generally used for planning, scheduling and controlling of repetitive type of projects (like construction projects) where one can make fairly accurate assessment of time for completion of each and every job required to be carries out to complete the project.
What is PERT
Program Evaluation and Review Technique (PERT) was first developed in 1958 by USA Navy special project office and a management consulting firm for planning and control of the Polaris sub-marine missile project. The technique of PERT was specially developed to help reducing the overall project time by as much as possible.
PERT networks are generally used in research and development types of projects which are non-repetitive in nature or for projects where it is difficult to allot definite time for performing each and every activity for want of information regarding past experience or knowledge to handle such projects.
Advantages of PERT & CPM
The various advantages of PERT/CPM methods are summarized below.
In the network technique of planning and scheduling, one is compelled to examine the complete project in advance and interact with everyone who is to be involved in the project thereby evolving a workable plan of the project. One is also forced to decide upon the extent of splitting of the project into smaller activities and to establish logical relationship between different activities.
It helps in dividing activities function wise and responsibility wise which makes it possible to co-ordinate the works of different agencies involved in the completion of the project.
It enables one to determine reasonably correct schedule for the completion of different events and the project as a whole based on the availability of resources (i.e. men, material, money and machines etc.)
It permits one to take advance actions and timely decisions to reduce delays in completion of different events.
It permits greater flexibility in having optimum utilization of resources thereby effecting economy.
It identifies activities critical to different stages of projects completion which in turn enables the management to pay greater attention to fewer activities instead of concentrating on all activities at all times with equal emphasis.
It enables one to exercise effective control on the project by way of periodic review and to adopt timely corrective measures to minimise slippage in the completion of the project.