- - The required network for the above information. F D E Fig . Example . Develop a network based on the following information: Activity : D E F G H Immediate predecessor: C,D C,D E F Using the immediate precedence relationships and following the rules of network construction, the required network is shown in following figure.
Fig . E D H F G Dummy activity: An activity which does not consume any resource or time, but merely depict the technological dependence is called a dummy activity. It is represented by dotted lines. Example .
Draw a network diagram for the project whose activities and their predecessor relationships are given below: Activity : D E F G H I J K Predecessor activity: D F H,I F,G Using the precedence relationships and following the rules of network construction, the required network diagram is shown in following figure Fig . D J E I K F G H DUMMY Example . Construct a network diagram for the following situation: A < D, E; B, D < F; C < G and B < H. Using the precedence relationships and following the rules of network construction, the required network is shown in following figure.
Fig . D DUMMY G F E H . . Critical path analysis For each activity an estimate must be made of time that will be spent in the actual accomplishment of that activity.
Estimates may be expressed in hours, days, weeks or any other convenient unit of time. The time estimate is usually written in the network immediately above the arrow. For the purpose of calculating various times of events and activities, the following terms shall be used in critical path calculations: E i = Earliest start time of event i - - Operations Research L j = Latest start time of event j t ij = Duration of activity ( i,j ) The next step after making the time estimates is the calculations which are done in the following ways: (i) Forward Pass Calculations (ii) Backward Pass Calculations. Forward pass calculations: We start