Create WBS

The WBS is a deliverable-oriented hierarchical decomposition of the work to be executed by the project team, to accomplish the project objectives and create the required deliverables. The WBS organizes and defines the total scope of the project. The WBS subdivides the project work into smaller, more manageable pieces of work, with each descending level of the WBS representing an increasingly detailed definition of the project work. The planned work contained within the lowest-level WBS components, which are called work packages, can be scheduled, cost estimated, monitored, and controlled.

The WBS represents the work specified in the current approved project scope statement. Components comprising the WBS assist the stakeholders in viewing the deliverables (Section 4.4.3.1) of the project.

5-5. : Create WBS: Inputs, Tools & Techniques, and Outputs

Section 5.3.1 Create WBS: Inputs

.1 Organizational Process Assets

Described in Section 4.1.1.4.

.2 Project Scope Statement

Described in Section 5.2.3.1.

.3 Project Scope Management Plan

Described in Section 5.2.1.4.

.4 Approved Change Requests

Described in Section 4.4.1.4.

Section 5.3.2 Create WBS: Tools and Techniques

.1 Work Breakdown Structure Templates

Although each project is unique, a WBS from a previous project can often be used as a template for a new project, since some projects will resemble another prior project to some extent. For example, most projects within a given organization will have the same or similar project life cycles and, therefore, have the same or similar deliverables required from each phase. Many application areas or performing organizations have standard WBS templates.

The Project Management Institute Practice Standard for Work Breakdown Structures provides guidance for the generation, development, and application of work breakdown structures. This publication contains industry-specific examples of WBS templates that can be tailored to specific projects in a particular application area. A portion of a WBS example, with some branches of the WBS decomposed down through the work package level, is shown in Figure 5-6.

Figure 5-6. Sample Work Breakdown Structure with Some Branches Decomposed Down Through Work Packages

.2 Decomposition

Decomposition is the subdivision of project deliverables into smaller, more manageable components until the work and deliverables are defined to the work package level. The work package level is the lowest level in the WBS, and is the point at which the cost and schedule for the work can be reliably estimated. The level of detail for work packages will vary with the size and complexity of the project.

Decomposition may not be possible for a deliverable or subproject that will be accomplished far into the future. The project management team usually waits until the deliverable or subproject is clarified so the details of the WBS can be developed. This technique is sometimes referred to as rolling wave planning.

Different deliverables can have different levels of decomposition. To arrive at a manageable work effort (i.e., a work package), the work for some deliverables needs to be decomposed only to the next level, while others need more levels of decomposition. As the work is decomposed to lower levels of detail, the ability to plan, manage, and control the work is enhanced. However, excessive decomposition can lead to non-productive management effort, inefficient use of resources, and decreased efficiency in performing the work. The project team needs to seek a balance between too little and too much in the level of WBS planning detail.

Decomposition of the total project work generally involves the following activities:

Identifying the deliverables and related work
Structuring and organizing the WBS
Decomposing the upper WBS levels into lower level detailed components
Developing and assigning identification codes to the WBS components
Verifying that the degree of decomposition of the work is necessary and sufficient.

Identifying the major deliverables of the project and the work needed to produce those deliverables requires analyzing the detailed project scope statement. This analysis requires a degree of expert judgment to identify all the work including project management deliverables and those deliverables required by contract.

Structuring and organizing the deliverables and associated project work into a WBS that can meet the control and management requirements of the project management team is an analytical technique that may be done with the use of a WBS template. The resulting structure can take a number of forms, such as:

Using the major deliverables and subprojects as the first level of decomposition, as shown in Figure 5-6.
Using subprojects as illustrated in Figure 5-6, where the subprojects may be developed by organizations outside the project team. For example, in some application areas, the project WBS can be defined and developed in multiple parts, such as a project summary WBS with multiple subprojects within the WBS that can be contracted out. The seller then develops the supporting contract work breakdown structure as part of the contracted work.
Using the phases of the project life cycle as the first level of decomposition, with the project deliverables inserted at the second level, as shown in Figure 5-7.

Figure 5-7. Sample Work Breakdown Structure Organized by Phase
Using different approaches within each branch of the WBS, as illustrated in Figure 5-8, where test and evaluation is a phase, the air vehicle is a product, and training is a supporting service.

Figure 5-8. Sample Work Breakdown for Defense Materiel Items

Decomposition of the upper level WBS components requires subdividing the work for each of the deliverables or subprojects into its fundamental components, where the WBS components represent verifiable products, services, or results. Each component should be clearly and completely defined and assigned to a specific performing organizational unit that accepts responsibility for the WBS component’s completion. The components are defined in terms of how the work of the project will actually be executed and controlled. For example, the status- reporting component of project management could include weekly status reports, while a product to be manufactured might include several individual physical components plus the final assembly.

Verifying the correctness of the decomposition requires determining that the lower-level WBS components are those that are necessary and sufficient for completion of the corresponding higher-level deliverables.

Section 5.3.3 Create WBS: Outputs

.1 Project Scope Statement (Updates)

If approved change requests result from the Create WBS process, then the project scope statement is updated to include those approved changes.

.2 Work Breakdown Structure

The key document generated by the Create WBS process is the actual WBS. Each WBS component, including work package and control accounts within a WBS, is generally assigned a unique identifier from a code of accounts. These identifiers provide a structure for hierarchical summation of costs, schedule, and resource information.

The WBS should not be confused with other kinds of breakdown structures used to present project information. Other structures used in some application areas or other Knowledge Areas include:

Organizational Breakdown Structure (OBS). Provides a hierarchically organized depiction of the project organization arranged so that the work packages can be related to the performing organizational units.
Bill of Materials (BOM). Presents a hierarchical tabulation of the physical assemblies, subassemblies, and components needed to fabricate a manufactured product.
Risk Breakdown Structure (RBS). A hierarchically organized depiction of the identified project risks arranged by risk category.
Resource Breakdown Structure (RBS). A hierarchically organized depiction of the resources by type to be used on the project.

.3 WBS Dictionary

The document generated by the Create WBS process that supports the WBS is called the WBS dictionary and is a companion document to the WBS. The detailed content of the components contained in a WBS, including work packages and control accounts, can be described in the WBS dictionary. For each WBS component, the WBS dictionary includes a code of account identifier, a statement of work, responsible organization, and a list of schedule milestones. Other information for a WBS component can include contract information, quality requirements, and technical references to facilitate performance of the work. Other information for a control account would be a charge number. Other information for a work package can include a list of associated schedule activities, resources required, and an estimate of cost. Each WBS component is cross-referenced, as appropriate, to other WBS components in the WBS dictionary.

.4 Scope Baseline

The approved detailed project scope statement (Section 5.2.3.1) and its associated WBS and WBS dictionary are the scope baseline for the project.

.5 Project Scope Management Plan (Updates)

If approved change requests result from the Create WBS process, then the project scope management plan may need to be updated to include approved changes.

.6 Requested Changes

Requested changes to the project scope statement and its components may be generated from the Create WBS process, and are processed for review and approval through the integrated change control process.

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Create WBS

Create WBS

Section 5.3.1 Create WBS: Inputs

Section 5.3.2 Create WBS: Tools and Techniques

Section 5.3.3 Create WBS: Outputs