Network Analysis

NA deals with projects

A project is defined as a set of jobs that are performed in a certain logical or technological sequence and it should be completed within the specified cost & meeting the performance standard & specification

NA is a powerful effective scientific method used to plan, schedule, regulate & control the various operations involved in the costing of project.

NA consist of

• Critical Path method analysis (CPM)
• Project/programme evaluation & review technique (PERT)
• Crashing analysis

Network Diagram

• A project can be represented be means of a diagram or arrow diagram. This diagram indicates the several activities that should be performed and indicating the inter dependence of those activities.
• The terms associated with the study
  • Activity (Job) : Each activity of a project is represented by an arrow as shown below.
  • Each arrow should have 2 circles known as node. They represent starting & finishing position of each activity
  • The length, shape, size direction of arrow have no relations or any significance to the magnitude of the activity
  • Activities are denoted be 1-2,1-3,1-4,2-3 and so on . This representation of activities is event orientation form. Sometimes activities can be denoted by A,B,C,D and this representation is named as activity orientation form.

Rules for drawing diagram

1. Network diagram should be drawn starting from the left side and moving towards right side
2. Each job should be represented by exactly one arrow
3. Two jobs should not be represented by 1 arrow nor 2 different arrows representing one job
4. For every 2 nodes there should be exactly one arrow connecting them. (The last 3 rules are called network logic)
5. Dummy activities should be indicated by broken lines ( -------->)
6. While drawing diagram avaoid the intersection of arrow. If avoidance is not possible then put a flyover as shown below.

• Case 2: If the activities are given in the form of A,B,C,D form

If a project is in the form of activity orientation then the predecessor relations for each activity should be given. In this situation we have to make certain analysis for the necessity of dummy activity. The analysis should be made in the following manner

1. 1.Examine the predecessor relation, if they contain single letter then dummy activity is not required, proceed with the drawing diagram
2. 2.If predecessor relation contains 2 letters together say PQ, then the necessity of dummy should be analyzed using the following table;

	If PQ start from same node	If PQ start from diff node
Repetition	DO	DO
P & Q are not repeated	Dummy is reqd from P to Q or Q to P	Dummy not reqd Heads of P & Q to be merged
P is repeated but not Q	Dummy is reqd from P--> Q	Dummy is reqd from P-->QQ
Q is repeated but not P	Dummy is reqd from Q-->P	Dummy is reqd from Q-->P
Both P & Q are repeated are individually or jointly with other letter	Dummy is reqd are from P--> new node Q-->same new node	Dummy is reqd are from P--> new node Q-->same new node

Points to note

1. In predecessor or relation, if PQ occurs as a------ whole second time then we should not say P is repeated, nor Q is repeated , nor both PQ repeated.
2. Any node, if no activity is emanating is called hanging node.
3. There should be exactly one & only one hanging node in the network diagram
4. If more than one hanging node exist, then all the hanging nodes should be merged & shown as a single node.
5. Node should be numbered while numbering tail number should be less & head number should be more. (not necessary that the difference is 1. This rule is called Furkraris Rule)