I know why there are so many people who love chopping wood. In this activity one immediately sees the results.

Albert Einstein

Gantt charts indicate the general sequence of work tasks, but they do not explicitly show the relationships among tasks, nor the impact of delaying tasks or of shifting resources. Planning and scheduling methods using networks do not have this inadequacy. They clearly show interdependencies among activities and enable planning and scheduling functions to be performed separately. Alternative plans can be analyzed and, afterwards, they can be scheduled according to the availability of resources.

This chapter and the next address the topic of project network development and describe the most widely used network-based approaches to project planning the precedence diagramming method (PDM), the program evaluation and review technique (PERT), and the critical path method (CPM).

7.1 LOGIC DIAGRAMS AND NETWORKS

The simplest kind of network, called a logic diagram, shows the major elements of a group of tasks and their logical relationship. It clearly exposes those tasks that must be completed before others can be started; this is called the precedence. Figure 7-1 is a logic diagram for getting up in the morning and getting dressed (for a male). The boxes represent tasks (or activities) and the arrows connecting them show the order in which they should occur (e.g., put on shirt before tie, put on pants and socks before shoes, etc.).

Figure 7-1: Logic diagram for getting up in the morning and getting dressed.

The...