Doing a work breakdown structure is one of the simplest things that you will do as a project manager, yet it is one of the things that many project managers and their staff do not do well. Part of the reason must be that it is so simple that many managers do not think that something so simple will be of use to them. In reality, the WBS is simple, but it is also one of the most useful tools in project management.
To do a WBS, you start at the top, which is the project level. The project is then broken down into subprojects. As we discussed, we could be doing a product breakdown at this point. Usually a project is first broken down into four to seven subprojects or products. Once the first level of the breakdown for the project has been completed, a different group of people on the project team can be used to break each one of the subprojects into sub-subprojects. In this way the proper expertise can be used for each area of the project.
The work of breaking each project and subproject down further and further continues until the level of breakdown is achieved at which an individual can be assigned to be responsible for the work of the defined sub-sub-sub … . . project. At this point we have what is usually called a task or an activity. There is plenty of flexibility in doing this, as there should be since each project and each project manager is unique and we do not want to burden the process with unnecessary rules and restrictions.
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While the WBS process is easy and simple to do, there are some difficulties. Most of these are problems created by forcing unnecessary rules onto the process. Some people get frustrated working hard to try to make the WBS come out according to some preconceived notion about what it should look like. Others reach high levels of frustration trying to conform to norms or standards that are imposed from outside the project. Generally these kinds of standards inhibit the process much more than they help it. The WBS should be unique to each project, and the flow from top to bottom should feel natural to those who are creating it.
As a guideline but not a rule, each level of the WBS should break the previous element into four to seven new elements. If a project seems to want an element to be broken down into more or fewer elements, then that is what should be done. Generally the guideline is a good one, however. If we consider a project that is broken down to four levels, we can see that there is a considerable disassembly of the project. Level one is the project; level two has as many as 7 subprojects; level three has 49, and level four has 343. This is probably more breakdown than most projects need.
The second guideline is that the elements of the WBS should be relatively the same size. This means that elements at the same level of breakdown should be close to having the same amount of budget as the others of the same level. This is just to help people understand what they are looking at when they look at the WBS. In the graphic for the WBS, each element is represented by a box of the same size. People will naturally think that each box represents a similar amount of work.
If elements on the same level represent large differences in budget, some of the stakeholders may think that they are similar in magnitude and give each of the elements the same attention. This can create problems for the project manager when she is trying to focus the attention of the stakeholders on some critical part of the project, and the stakeholders want to focus on another element in the WBS. In large projects there will be several levels of breakdown, and there will be several elements on each level.
The breakdown process can be accomplished by different groups of people. These groups have different cumulative skills and can meet at different times to accomplish the breaking down of their individual elements. Thus when we are breaking down the software development part of the project, we can have the programmers involved, and when we are breaking down the mechanical design part of the project, we can have the mechanical designers work on that part. This allows us to have the appropriate people work on defining all of the tasks that are necessary to complete the project. The meetings we hold to do this should take place in less than two hours and should have fewer than ten people attending.
The breakdown process continues until the level of detail is reached at which a single person can be assigned to complete that small piece of project work. It is important that the breakdown process continue to this point because the individual work assignments or tasks that are identified at this level become the fundamental building block for schedule development and detailed budget estimates. This is not to say that the individual person in charge of a task is not allowed to further break down their individual tasks if it is convenient. Reporting the WBS can include all of the minutest detail, or it may suppress some of the detail according to the communications needs of the project.
In the two examples in WBS EXAMPLES and WBS EXAMPLES, we see the work breakdown structure for building a house. In Figure 2-9 we have divided the work of building the house by discipline. The work is divided into skill areas: masonry, carpentry, plumbing, and electrical. All the work of building the house is forced to fall into one of these four disciplines, or we must add another element at that level. This approach makes things simple for dividing up the work. If we want to discuss the masonry work for the project, we gather the masonry workers. If we want to talk about the electrical work, we gather the electricians and so on. This makes it unnecessary for the electricians to go to a meeting where masonry work will be discussed. The project organization can even fit into the WBS, but this is not a necessary thing.
In WBS EXAMPLES the project is broken down by phase. Phases are points in time at which a significant part of the project is complete. In the example, we have divided our house project into three phases: foundation, rough construction, and finish construction. All of the work of building the house from the very beginning to the end of the foundation phase is included in this phase. This would be clearing the land, getting permits to build, excavating, building forms, and pouring concrete for the foundation. We begin the second phase as soon as the first phase is complete. This phase is completed when the walls, roof, doors, and windows are in place, and the house can be secured. The third phase begins at this point and continues to the end of the project.
Notice that in a phased WBS, one phase ends when the next begins. This is helpful in placing decisions to continue with the project. In a research project the end of a phase might include justification and approval to move on to the next phase. The difficulty with this arrangement is that if you need to call a meeting for phase one, you will probably include all of the people of all of the disciplines involved in the whole project.
While this is only an example showing two ways of doing the work breakdown structure, by discipline and by phase, there are many other ways that the breakdown can occur. The method of breaking down can even be changed from level to level within the WBS. It might be convenient to start with a product breakdown structure in the first level or two of the WBS. Each of the subproducts in the result might be broken down by phase and then, further down the WBS we might ultimately shift to skills breakdown. The point is that the WBS should be done in a smooth and natural way, and it should be relatively simple to accomplish. If the WBS is difficult, the process will be difficult and hard to understand.
To complete the WBS we need to test the accuracy of the lowest level of breakdown. This level should contain all of the work necessary to complete the project. Each of these lowest level elements or tasks has a single individual who is responsible for it. From the budget standpoint, each element at this level has a budget designed so that the total budget for all of the elements at this level equals the total operating budget for the project. It is also true that if all of the budget for each of the elements at each level were added together, we would get the total operating budget for the project.