Page 237 - DCOM303_DMGT504_OPERATION_RESEARCH

Operations Research Dilfraz Singh, Lovely Professional University

Notes Unit 12: Critical Path Method and PERT

CONTENTS
Objectives
Introduction

12.1 CPM/Pert Network Components
12.2 Rules in Constructing a Network
12.3 Critical Path Method (CPM)

12.3.1 Time Estimates: Earliest Time and Latest Time
12.4 Project Evaluation Review Technique (PERT)
12.5 Summary
12.6 Keywords
12.7 Review Questions

12.8 Further Readings

Objectives

After studying this unit, you will be able to:

 Understand the importance of CPM and PERT techniques for project management
 Construct network diagrams
 Learn about the concept of time estimates, slack and float.
 Learn how to find critical paths.

Introduction

Any project involves planning, scheduling and controlling a number of interrelated activities
with use of limited resources, namely, men, machines, materials, money and time. The projects
may be extremely large and complex such as construction of a power plant, a highway, a
shopping complex, ships and aircraft, introduction of new products and research and development
projects. It is required that managers must have a dynamic planning and scheduling system to
produce the best possible results and also to react immediately to the changing conditions and
make necessary changes in the plan and schedule. A convenient analytical and visual technique
of PERT and CPM prove extremely valuable in assisting the managers in managing the projects.
Both the techniques use similar terminology and have the same purpose. PERT stands for Project
Evaluation and Review Technique developed during 1950s. The technique was developed and
used in conjunction with the planning and designing of the Polaris missile project. CPM stands
for Critical Path Method which was developed by DuPont Company and applied first to the
construction projects in the chemical industry. Though both PERT and CPM techniques have
similarity in terms of concepts, the basic difference is, PERT is used for analysis of project
scheduling problems. CPM has single time estimate and PERT has three time estimates for
activities and uses probability theory to find the chance of reaching the scheduled time.

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