Network fundamentals:

Networks are composed of events and activities as defined below:

Event: An event is defined as the starting or ending point of an activity or a group of activites. It represents a milestone and does not consume time or resources. Event is described by a circle (o). Activity:

Activity: is the work required to proceed from one event to another It consumes therefore time and resources. It is represented by an arrow(->)

  • To draw network diagram an interdependencies between events and activites must be identified so that master plan can be developed which illustrate the up-to-date picture of operations during the project.
  • Network analysis provides valuable information for planning, integration of plans, time scheduling ,  and resource management.
  • The primary purpose of network is to eliminate  crisis management by providing a pictorial representation of the total program from which the time estimates such as Early starting time(EST) and Late starting time(LST) and their impact can be made.
Network Rules:
  • Each activity must have a preceding and a succeeding event
  • Each Event should have a distinct(unique) number.
  • There should not be loop in the project network as shown below:
  • Note More than one activity can have the same preceding and succeeding event
  • Any number of activities may merge with an event.

Network Development

1.Enmurate all those activities in the Project which needs close monitoring to    complete them in time.
2.Define each activity as
   Preceding activity(the activity which preceed it).
   Succeding activity(the activity which followed).
   Concurrent activity(the activity that can be done concurrently)
3.Estimation of time for the completion of each activity.

The estimation of time for the completion of each activity is important in the network analysis. This can be done using three possible assumptions.

I. Optimistic time(a):
         This time assumes that every thing will go accordingly to with minimum a mount ofdifficulties and such situation may occur approximately 1 percent of time.

II. Most pessimistic time(b):
          This time assumes that every thing will not go according to plan and that the maximum potential difficulties will develop and may occur approximately one percent of time.

III. Most likely or normal time(m):
          This is the time that would most often occur should this effort be reported over over again.

The estimated time of the completion of an activity is given by:

              te= (a+4m+b)/6
Where
         te = estimated time          
          a  = most optimistic time          
          m = normal time
          b = most pessimistic time

Standard Devation

Standard devation of the estimated time(te):
sd (te) = (b-a)/6