Page 177 - DCAP304_DCAP515_SOFTWARE_PROJECT_MANAGEMENT

Unit 9: CPM /PERT

Notes

Notes Note that the project duration is estimated at 16 days using the original task duration
estimates, which include contingency for each task.
Figure 9.2 shows the critical path (C1-C2-C3) for a project manager using TPM, and it is the
starting point for resolving any resource contention problems.

Step 2: Converting the Early Schedule to the Late Schedule and Adding
Resources

The first thing that a project manager using CCPM does is convert the task schedule to the late
schedule. This is shown in Figure 9.3. Note that this conversion removes the slack associated
with the sequence defined by tasks A1–A2 and B1–B2. In fact, it removes all of the free slack and
total slack associated with any task or task sequence in the project. Note also that the 50 percent
duration estimates have replaced the original estimates, which included contingency. In doing
that, the project duration has been reduced from the original 16 days to 8 days. We have also
added the three resources (Amit, Mukesh, and Santa) to the tasks to which they have been
assigned. Note that there is a resource conflict with Mukesh on tasks A2 and B2. Also note that
the project duration reduces to eight days when the contingencies are removed.

Figure 9.3: The Late Schedule with Resource Assignments

Step 3: Resolving Resource Conflicts

In general, resource conflicts are removed by beginning with the task sequence that has the least
slack. After resolving that conflict, move to the task path that now has the least slack. Continue
in this fashion until all resource conflicts have been resolved. In our example, the critical chain
(C1-C2-C3) does not have any resource conflicts. The next task path to consider is A1-A2. In this
case, Mukesh would be scheduled to work on A2, and that means pushing his work on B1 to an
earlier date. This resolution is illustrated in Figure 9.4.
Figure 9.4: One way to Resolve the Resource Conflict

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