Page 125 - DMGT302_FUNDAMENTALS_OF_PROJECT_MANAGEMENT
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Fundamentals of Project Management
Notes At Event 3, we have to evaluate two predecessor activities – Activity 1-3 and Activity 2-3, both of
which are predecessor activities. Activity 1-3 gives us an Earliest Start of 3 weeks at Event 3.
However, Activity 2-3 also has to be completed before Event 3 can begin. Along this route, the
Earliest Start would be 4 + 0 = 4. The rule is to take the longer (bigger) of the two Earliest Starts.
So the Earliest Start at event 3 is 4.
Similarly, at Event 4, we find we have to evaluate two predecessor activities – Activity 2-4 and
Activity 3-4. Along Activity 2-4, the Earliest Start at Event 4 would be 10 wks, but along Activity
3-4, the Earliest Start at Event 4 would be 11 wks. Since 11 wks is larger than 10 wks, we select it
as the Earliest Start at Event 4. We have now found the longest path through the network. It will
take 11 weeks along activities 1-2, 2-3 and 3-4. This is the Critical Path.
Task Describe the steps for drawing the CPM/PERT Network.
The Backward Pass – Latest Finish Time Rule
To make the Backward Pass, we begin at the sink or the final event and work backwards to the
first event.
At Event 3 there is only one activity, Activity 3-4 in the backward pass, and we find that the value
is 11–7 = 4 weeks. However at Event 2 we have to evaluate 2 activities, 2-3 and 2-4. We find that
the backward pass through 2-4 gives us a value of 11–6 = 5 while 2-3 gives us 4–0 = 4. We take
the smaller value of 4 on the backward pass.
Self Assessment
State whether the following statements are True or False:
5. Planning, Scheduling and Control are considered to be advanced Managerial functions.
6. There are many variations of CPM/PERT which have been useful in planning costs,
scheduling manpower and machine time.
7. Non-critical activities can be replanned, rescheduled and resources for them can be
reallocated flexibly.
8. Each activity in a PERT/CPM Network is represented by a circle symbol.
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