We get started developing the project work breakdown structure by getting the scope and major deliverables defined by the project sponsor. We can’t start work on the project work breakdown structure until we have that data because that is the starting point for the WBS. We also need a well defined scope and major deliverables where each of the end elements is defined by a metric; a number that tells us how we’ll measure the results. As an example, if we’re doing a project where we have to reduce the noise in a workspace, the sponsor might define success as, “The average decibel rating of the workspace is 64 dB.” That gives us a metric to use. We would break that down into its major deliverables and break each of those down into smaller deliverables down to the level of individual assignments.
How to Build a Project Work Breakdown Structure
Project Work Breakdown Structure Step 1. Break down the scope into the project’s high-level deliverables – we start building the project work breakdown structure by decomposing or breaking down the scope into 4 to 7 high-level deliverables in the project. Each of those deliverables is defined with a metric, which is an acceptance criterion for the deliverable. In other words, we define the way we will measure the acceptability of the deliverables as part of our plan. Here are some examples of high-level deliverables from different projects:
- A. Payroll data entry operators can enter 60 transactions/hour with 99.5% accuracy. This high-level deliverable will be produced by system programmers and analysts. But we are measuring the acceptability of the work productivity of the people who use the system.
- B. The ambient temperature in the grocery store is between 71° and 73° 99% of the time. This high-level deliverable will be assigned to a heating and ventilating subcontractor. We are going to measure that subcontractor’s work by the HVAC system’s ability to meet the specified metric.
- C. Attendees at a payroll training class score 82% or higher on a test at the end of class. This high-level deliverable will be produced by the company’s trainers. We will measure their work on how well the attendees know the new payroll procedures based on the attendees’ test results.
- D. Sales of a model J-27 device exceed $425,000 in the first 60 days after launch. This is a deliverable that sales will produce in combination with advertising.
Sometimes we can work on all of the high-level deliverables simultaneously. In other projects, we will work on them sequentially, which means the first deliverable must be completed before we can start work on the second deliverable.
Project Work Breakdown Structure Step 2. Break down the high-level deliverables into supporting deliverables – we next take each of those high-level deliverables and break it down into the supporting deliverables that are necessary to produce it. As an example, the high-level deliverable described above, “Payroll data entry operators can enter 60 transactions/hour with 99.5% accuracy,” might be decomposed into several supporting sub-deliverables such as:
a. User management approves systems design and acceptance criteria
b. System analysts’ design meets company IT standards and is approved by quality assurance
c. Programmers’ coding company design criteria and is accepted by the IT analyst
d. In user testing, data entry operators can enter 60 transactions per hour with 99.5% accuracy
The training class deliverable described in “C” above may require the following supporting sub-deliverables:
a. User managers approve training class curriculum
b. User managers approve final examination
c. Training department management approves the course design, training slides and lecture notes for the trainers’ use
d. Pilot group of students has an 88% pass rate on the examination (the pilot passing rate is higher than the high-level deliverable)
You’ll note that some of these sub-deliverables have metrics and that is the best kind of acceptance criteria. However, in some design tasks we can’t specify a number. So we use the approval or acceptance of another party to measure the success of the sub-deliverable.
Project Work Breakdown Structure Step 3. Break down supporting deliverables as necessary to reach individual team member assignments. We continue to break down the sub-deliverables into their components until we reach assignments that we can assign to an individual. Typically, project task assignments should have a duration of between three and ten days. New employees or trainees will be given assignments at the low end of that range. Experienced professionals or experts will be given assignments at the high-end of that range. But every assignment should have a metric or other measure of the acceptability of the deliverable. The reason this is so important is that team members need to know what is expected of them before they start work.
Project Work Breakdown Structure Step 4. In addition to the hierarchy of deliverables, the project work breakdown structure can also contain milestones. These are fixed dates by which certain components of the project have to be completed. You should not use milestones to set your target completion dates because the scheduling software will calculate those. We use milestones to indicate external dates that are legally mandated or required by government regulation.
Project Work Breakdown Structure Step 5. The final step in building a professional-grade project work breakdown structure is to develop the assignment work packages. Usually the project manager will work with the individual who is going to produce the deliverable to finalize the details of the assignment. The work package contains information about the deliverable and its associated metric. It also has information about the approach the team member will take to produce the deliverable as well as procedural and documentation standards that must be met as the deliverable is produced. Last of all, we use the work package to document the team member’s work estimate. The best practice estimating technique is three-point estimating which provides a team member the opportunity to reflect the risk of the task in the estimate. Once the estimate is complete, it is the contract between the project manager and team member. It specifies what is going to be produced, how long it should take and how much it should cost. As you can see the creation of the project work breakdown structure accomplishes a number of critically important things for the project. Specifically the entries in our project work breakdown structure are:
1. The assignments for each of our team members which specify exactly what they’re supposed deliver
2. The bench marks we will use to measure and report on progress
3. The basis for our estimates of duration and cost. Accuracy in those estimates is another reason why we have to be crystal clear about what is expected.