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5 - PROJECT SCOPE MANAGEMENT

An example of rolling wave elaboration of the WBS for the ATM project (see Figure 5-3) is illustrated in Figure
5-4, where the details of constructing the financial transaction component have been added, perhaps after some
prototyping and feasibility analysis once the project was underway. The work package for the financial transaction
component in Figure 5-3 (FINAT) is decomposed into work packages shown in Figure 5-4 for the four subordinate
software components plus the FINAT integration and test task. Note that the product components are denoted in
boldface font. Also, note the decision to reuse existing recorder software from another software product. A work
package for a software construction task includes the work needed to accomplish detailed design, coding, unit
testing, and integration and testing of the composite software module (e.g., the validator module in Figure 5-4). 5

Rolling wave elaboration of an activity-oriented software WBS is typically accomplished periodically, perhaps
monthly, to accommodate increased understanding of the problem to be solved. Rolling-wave elaboration also
may be accomplished as circumstances dictate, such as changes to requirements, schedule, budget, resources,
or technology.

ATM Project

1. 2. 3. 4. 5. 6.
Manage Analyze and Construct Verify Validate Deploy
Project Design Software Software Software Software

3.1. 3.2. 3.3. 3.4. 3.5.
Reuse Construct Construct Buy Integrate
ATMSD FINAT MAIND COMM and Test
ATMSD, FINAT,
MAIND, COMM

3.2.1. 3.2.2. 3.2.3. 3.2.4. 3.2.5.
Construct Construct Reuse Construct Integrate & Test
Validator Processor Recorder Terminator Validator,
Processor,
Recorder,
and Terminator
ATMSD: Software Drivers Modules
LEGEND FINAT: Financial Transactions
MAIND: Maintenance & Diagnostics
COMM: Communication Package

Figure 5-4. Rolling Wave Elaboration of Activity-Oriented WBS

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