Building a Work Breakdown Structure
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.
On projects I’ve worked on, the project team would go into a conference room and use post it notes for each piece of work until we reached something that was a week or less. NOTE: It’s easiest to bring a roll of paper to put the post it notes on so you can roll the whole thing up to input it into soft format.
The WBS represents the work specified in the current approved project scope statement. Components comprising the WBS assist the stakeholders in viewing the deliverables of the project.
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.
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.
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.
· Using subprojects 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.
· Using different approaches within each branch of the WBS, where test and evaluation is a phase, the air vehicle is a product, and training is a supporting service.
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.
Outputs of Creating a WBS:
· 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.
· 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.
The 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.
The Scope Baseline
The approved detailed project scope statement and it’s associated
WBS and WBS dictionary are the scope baseline for the project. The next step is to estimate all of the work packages and create your baseline schedule.