Work Breakdown Structure

The purpose of a Work Breakdown Structure, or WBS, is breaking the work that needs to be done for a project into manageable steps, which contain a defined deliverable. The PMBOK (PMI, 2000) de- fines a WBS as follows: “A deliverable oriented grouping of project elements that organizes and de- fines the total work scope of the project. Each descending level represents an increasingly detailed definition of the project work”. The WBS is a hierarchical breakdown of work. By subdividing the pro- ject into smaller, manageable steps, it makes sure that everyone knows their responsibilities, and costs can be controlled better due to the smaller units of control (Heinze, 1996).

Advantages of the WBS

Oberlender (2000) describes the WBS as the cornerstone of the project plan: “in order to manage a whole project, one must manage and control each of its parts”. The five main authors on project management for this report mention the following advantages of using a WBS:

Author Advantages of WBS:

Turner (1993) • It provides better control of work definition (3)

• It allows work to be delegated in coherent packages (1)

• It allows work to be defined at an appropriate level for estimating and control for the current stage (3)

• It allows risk to be contained within the WBS PMI (2000, PMBOK) • Defines the scope of the project

• Provides structure for a hierarchical summation of costs and resources (2) • Smaller, more manageable components (1)

• Identifies the project deliverables and processes that will need resources (3)

Oberlender (2000) • Divides the project into identifiable parts that can be managed (1) • The WBS is the cornerstone of the project work plan (4)

• Defines the work to be performed, identifies the needed expertise, assists in selection of the project team, and establishes a base for project sched- uling and control (3)

• Manageable: specific authority and responsibility can be assigned (1) • Independent, or with minimum interfacing with and dependence on other

ongoing elements (3)

• Integretable so that the total package can be seen (4) • Measurable in terms of progress (2)

Table 3.3: The advantages of a WBS, according to five main authors.

From this overview, some main advantages of a WBS have been composed, by putting the work of all five main authors together:

1. The WBS allows the project to be divided into smaller, manageable components; each with their own authority and responsibilities.

2. The work is defined by project deliverables that are measurable in terms of progress. Esti- mating and controlling is possible through a hierarchical summation of costs and resources. 3. The project becomes controllable by clearer work definition, and smaller steps that can be

reviewed and controlled independently.

4. It becomes easier to have an overview of the project as a whole, with different elements that are independent, but form coherent packages that make up the whole.

Levels of the WBS

The WBS should essentially break the work down into project elements to which costs will be allo- cated. However, different sources of literature about WBS disagree on the amount of levels in which a WBS should be subdivided. A small example:

LEVELS OF THE WORK BREAKDOWN STRUCTURE

Kerzner (2001) Turner (1993) Sullivan et al. (2009)

Managerial levels

1 Program Program 1 Project

2 Project Project 2 Major work elements

3 Task Areas of Work 3

Technical Levels

4 Subtask Work Package 4

5 Work Package Activity 6 Level of Effort Task

Item Step

Table 3.4.: Levels of the WBS, according to Kerzner (2001), Turner (1993), and Sullivan et al. (2009)

Kerzner (2001) mentions the six-level structure as shown above as the most common structure. Level 1 is the total program, composed of a set of projects, and these are subdivided further among two types of levels: the managerial and technical levels. The upper three (managerial) levels are de- scribed by Kerzner as summarizing levels for reporting purposes, not related to one specific depart- ment. The lower levels are usually for in-house control, and effort required by departments or sec- tions is defined here, in subtasks and work packages.

subdivided into tasks, or the other way around. Sullivan et al. (2009, p.97) have a similar approach: a project is subdivided into its major work elements, and then further developed into “successive lev- els of detail”. More important than the amount of levels in a WBS, are the work packages they con- tain. They are explained in the following paragraph.

Work Packages

Although there is no consent on the levels of elements in a WBS, there is consent in most literature on one thing: work packages describe the critical level of managing a WBS and are the most im- portant elements of the WBS. Some authors describe them as the items at the lowest level (Ober- lender, 2000; PMI, 2000). Looking at table 3.4, this does not correspond with the levels as described by Kerzner or Turner. However, it can be explained by the PMI and Oberlender: the work package is the smallest unit in the WBS, and must be defined in sufficient detail. They can in turn be further decomposed into a subproject WBS. Usually, the project manager will then assign a scope of work to another organization or department that must plan and manage the scope of work at a more de- tailed level than the project manager in the main project (PMI, 2000; Oberlender, 2000). Kerzner (2001) describes the work package level as “the level at which the project is managed”, and states that in his overview, the work package can exist at any level below level 1 (see table 3.4).

Work packages should be designed in a way that cost account managers and work package supervi- sors can clearly distinguish one package from another. In order to do so, they are ideally short- termed. But that short-term wish should not lead to forced cutoff points; work packages are natural subdivisions of effort planned according to the way the work will be done. The reason for them hav- ing to be short-termed is that if they are, little assessment of work-in-progress is needed, and evalu- ating the status of the project can be done mainly by looking at which work packages are completed. The longer they take, the more difficult and subjective it becomes to assess how far the work has come along in terms of time and budget (Kerzner, 2001).

Heinze (1996) defines three basic rules for work packages: all work packages at a given level should be comparable in terms of completion time and costs, they must have a definable output and a spe- cific product that must be generated for the task to be complete, and every work package must have a definable beginning and end. The definable output/specific product rule is in accordance with the view of Turner (1993) and the PMI (2000) that projects should focus on results through the WBS, and that the WBS should be deliverable-oriented.

Milestone planning

The focus on deliverables resembles Turner’s (1993) focus on results. The milestone planning as de- scribed by Turner (1993), is related strongly to the WBS: milestones are the deliverables of work packages. Turner states that it is common in developing a project plan to define the packages of work first and then define the deliverable that results from them; however, it is better to define the deliv- erables, or milestones first. Focusing on the deliverables can help delegate work to subproject teams: they can plan their own work to deliver that milestone by a certain date independently of the rest of the project team. The milestone plan will, as a result, show the logical sequence of the conditions that a project must pass through to achieve its final objectives (Turner, 1993).