Page 242 - DCOM303_DMGT504_OPERATION_RESEARCH

Unit 12: Critical Path Method and PERT

Notes
Example: Draw a network for a house construction project. The sequence of activities with
their predecessors are given in Table 12.1, below.
Table 12.1: Sequence of Activities for House Construction Project

Name of Starting and Description of activity Predecessor Time duration
the activity finishing event (days)
A (1,2) Prepare the house plan -- 4
B (2,3) Construct the house A 58
C (3,4) Fix the door/windows B 2
D (3,5) Wiring the house B 2
E (4,6) Paint the house C 1
F (5,6) Polish the doors/ D 1
windows

Solution:

Figure 12.11: Network Diagram Representing House Construction Project
Polish the doors
Fix the doors (2 days) (1 day)
4 E
Prepare the Construct the C
house plan house
6
1 2 3
A B
(4 days) (58 days) D F
5 Paint the house
Wiring the (1 day)
house (2 days)
The network diagram in Figure 12.11 shows the procedure relationship between the activities.
Activity A (preparation of house plan), has a start event 1 as well as an ending event 2. Activity
B (Construction of house) begins at event 2 and ends at event 3. The activity B cannot start until
activity A has been completed. Activities C and D cannot begin until activity B has been completed,
but they can be performed simultaneously. Similarly, activities E and F can start only after
completion of activities C and D respectively. Both activities E and F finish at the end of event 6.

Example: Consider the project given in Table 12.2 and construct a network diagram.
Table 12.2: Sequence of Activities for Building Construction Project

Activity Description Predecessor
A Purchase of Land -
B Preparation of building plan -
C Level or clean the land A
D Register and get approval A, B
E Construct the building C
F Paint the building D

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