Principles of Sequencing and Scheduling, 2nd Edition

16Network Methods for Project Scheduling

16.1 Introduction

This is the first in a module of four chapters covering classical and emerging project scheduling techniques. Here, we introduce the quintessential network methods for project scheduling, namely, critical path method (CPM) and program evaluation and review technique (PERT). Although we mention some modern insights, essentially this chapter could have been written in the early 1960s. However, several of the historical assumptions it is based on can no longer be considered tenable or necessary. It is not that these weaknesses were not known – most of them were already covered in the textbooks of the 1970s – but that they have been allowed to stand due either to inertia or to a lack of better models. The next chapter focuses on sequencing and briefly touches developments spanning half a century. The third chapter is about project analytics and introduces recent results that make it possible to generate valid simulated samples for a new project, based on historical information regarding other projects. The last chapter completes the module by adding safe scheduling analysis, based on such simulated samples. The chapter also shows how to implement safe scheduling hierarchically. Altogether, but especially in Chapters 18 and 19, the module presents a contemporary version of the PERT/CPM combination, which we also call PERT 21 (or PERT for the twenty‐first century).

Network models are widely used in the formulation of resource ...