Page 178 - DCAP304_DCAP515_SOFTWARE_PROJECT_MANAGEMENT

Software Project Management

Notes The other way to resolve the resource conflict is to have Ernie work on B2; then after Amit has
completed A1, Mukesh can work on A2. This resolution is illustrated in Figure 9.5. The second
choice extends the duration of the project.

Figure 9.5: Another way to Resolve the Resource Conflict

This simple example illustrates the major difference between TPM and CCPM. TPM uses the
early schedule as the base for all management decisions. CCPM uses the late schedule. TPM
focuses only on the critical path and manages in accordance with that. CCPM focuses on the
paths with resource constraints and manages in accordance with the best use of the resources.

Notes It does so by using the critical path but only to identify the chains with the least
slack and prioritizes resource use based on the minimum slack paths. To protect the scarce
resources, CCPM uses the concept of buffers.

Self Assessment

Fill in the blanks:
8. The traditional project manager would next conduct a resource ………………… exercise
targeting resource usage on the critical path.

9. The first thing that a project manager using CCPM does is …………………….. the task
schedule to the late schedule.
10. In general, resource conflicts are removed by beginning with the task ………………… that
has the least slack.
9.4 Defining Buffers

Buffers are segments of time that are placed at the end of a sequence of tasks for the purpose of
protecting the schedule of those tasks. Buffers can also be used to protect cost, much like a
contingency for unexpected expenses in a budget. The size of time buffers is based on the total
duration of the sequence of tasks to which they are attached. The size of the buffer is determined
by calculating the total of the contingencies in the tasks that make up the sequence.

9.4.1 Types of Buffers

The three main types of buffers are as follows:

 Project buffers
 Feeding buffers
 Resource buffers

172 LOVELY PROFESSIONAL UNIVERSITY