Network Analysis

1. Principle of Network Analysis

The network analysis techniques, developed between 1950s and 1960s, have now come to be used as an effective management tool for planning, scheduling and controlling of complex projects.

The term project network analysis is a general term covers all the network techniques used for planning, scheduling and controlling of projects. The three techniques commonly used are as follows:

1. Critical Path Method (CPM)
2. Program Evaluation and Review Technique (PERT) and
3. Precedence Diagramming Method (PDM) or Precedence Network Analysis (PNA).

These network techniques produce time-oriented diagrams having activities organised into a logical order.

2. Network Diagram

Network Diagram is a graphical flow plan of the activities that are to be accomplished for completing the project. The precedence and succedence relationships between activities are identified first.

Sequencing activities refers to finding out the logical relationships among the activities of a project and arranging them accordingly. By studying the project features the different activities involved in a project the concerned officer-in-change of the project establishes the precedence-succedence relationships between the activities.

While deciding the logical relationships between the different activities, activities which are mandatory to be operated before some of the activities to be taken up have to be identified. In addition there may be certain activities which may not be mandatory dependencies (such activities are called discretionary dependencies) are to be identified. After finalising all the activities and finding their characteristics the network diagram for the project can be drawn.

Activities of construction of a building are given in Table 31.2 and shown as network diagram in Fig. 31.5.

Table 31.2 Activities of construction of a building

Figure 31.5 Network diagram for construction activity

3. Definitions of Network Techniques

(i) Critical Path Method (CPM)

In a network the sequence of activities arranged in each path will have different duration. The path that has the longest duration is called critical paths.

(ii) Program Evaluation and Review Technique (PERT)

It uses three times, viz., optimistic time estimate, pessimistic time estimate and most likely time estimate.

(iii) Precedence Network

Here each activity is represented by a rectangular or square box. The time duration of the activity is incorporated inside the modal box.