- Describe a work breakdown structure and how it relates to activities.
- Describe the use of graphic representations for time management.
According to the Project Management Institute (PMI), project time management includes the following elements (Project Management Institute, Inc., 2008):
- Define activities
- Sequence activities
- Estimate activity resources
- Estimate activity durations
- Develop schedule
- Control schedule
The list of activities, their relationship to each other, and estimates of durations and required resources comprise the work breakdown structure (WBS). The project WBS is a hierarchical—classified according to criteria into successive levels—listing and grouping of the project activities required to produce the deliverables of the project. The WBS represents a breakdown of the project into components that encompass the entire scope of the project. Each level of the WBS hierarchy represents a more detailed description of the project work so that the highest level represents broad categories, and the lower levels represent increasing amounts of detail.
Larger and more complex projects often require a larger WBS. The size of the WBS is directly related to the amount of work on the project and how that work is divided into work packages. The WBS can be developed around the project phases or the project units or functions that will be performing the work. A WBS organized around the project phases facilitates the understanding of the amount of work required for each phase of the project. A WBS developed around the project units or functions of the project facilitates the understanding of the amount of work required for each function.
The following example, named John’s move, has a low level of complexity compared to a larger project. Normally, this project would not receive the amount of detailed planning described in the following examples, but the authors chose to use a basic project that is familiar to most students to help them focus on learning the new concepts.
John has a small but important project. He has accepted a job in Atlanta and now has to move from Chicago to Atlanta and be there, ready to work, right after the Christmas holidays. If the furniture arrives in good condition at least two days before John starts work, and for less than Five thousand dollars, the project will be a success. The move to Chicago five years ago cost five thousand dollars, but John is smarter now and will use his friends to help, so he is confident he can stay within budget.
Developing a WBS begins by defining and developing lists of all activities—work performed on the project that consumes project resources, including cost and time—needed to accomplish the work of the project. The first draft of the WBS includes activities at the highest level of the hierarchy or the management level and typically includes the major activities or summary activities required to accomplish the deliverables identified in the project scope of work.
Top-Level Activities in Move Planning
On John’s move project, these top-level activities are numbered 1, 2, 3, and so on. For example, a plan for the move is the major deliverable from 1 Plan Move, as shown below.
Figure 8.3 Top Level of WBS
- Plan Move
- Project Closeout
The work breakdown structure is then decomposed—broken down into smaller units. The 1.1, 1.2, and 1.3 numbers are the first subdivision of the work. For example, one of John’s Summary Level Activities is Packing (3.0). Although some minor packing (delicate items: 2.4) are packed under another summary activity, 3.3 is the major packing and includes the coordination and support of labor (friends Dion and Carlita). The activity is then decomposed—separated into basic elements—to the next level by listing the individual rooms that need packed, as shown below.
Figure 8.4 Major Activity Decomposed into Smaller Activities
3.1. Confirm Dion’s and Carlita’s help
3.2. Pick up donuts and coffee
3.3. Pack apartment
3.3.1. Pack kitchen
3.3.2. Pack living room
3.3.3. Pack bedroom
3.3.4. Pack remaining items
The WBS could be decomposed further to a greater level of detail by listing the tasks needed for each activity. For example activity 3.3.3, Pack Bedroom, can be decomposed into additional tasks, such as 22.214.171.124 Pack Closet, 126.96.36.199 Pack Drawers, and 188.8.131.52 Pack Blankets. This type of numbering of the activities is called intelligent numbering. In intelligent numbering, the numbering system has meaning so that a member of the project team knows something about the activity by the number of the activity. For example, any activity associated with packing begins with a 3; even picking up donuts can be an activity that supports packing. The donuts are a form of payment for the labor of Dion and Carlita.
The WBS is developed or decomposed to the level that the manager needs to control or manage the project. Typically, larger and more complex projects require a more detailed WBS.
Estimation of Duration
After the project team has created the WBS, each activity is reviewed and evaluated to determine the duration (how long it will take to accomplish from beginning to end) and what resources (time, materials, facilities, and equipment) are needed. An estimate is an educated guess based on knowledge, experience, and inference—the process of deriving conclusions based on assumptions. The accuracy of the estimate is related to the quality of the knowledge and how that knowledge is applied. The person with the most knowledge may not be the most objective person to provide duration estimates. The person responsible for the work may also want to build in extra time. Multiple inputs into the duration estimate and a more detailed WBS help reduce bias—the making of decisions based on a prejudged perspective.
The unit of time used to develop the activity duration is a function of the level of detail needed by the user of the schedule. The larger and more complex the project, the greater the need for detail, which usually translates into shorter durations for activities.
Duration Estimate for Training
On a new plant start-up, the plant manager may need to know when the new employees will start training, when they will be fully trained, and when they can begin working in the plant. The plant human resources manager may need to know what skills workers need and how much time each training class will take. The schedule detail the HR manager needs will include activities to locate facilities, schedule training, write contracts for trainers, and manage the initiation of training classes. The trainer will need an even greater level of detail, which could be measured in days or even hours.
On our John’s move example, the project schedule may have been just as effective without detailing the packing of the individual rooms in the old apartment. If we deleted these items, would John know when he needed to pack each one of these rooms? If the answer is yes, then we may not need that level of detail.
The activity duration is the length of time the activity should take to complete from beginning to end. The unit of duration is typically working days but could include other units of time such as hours, weeks, or months. The unit chosen should be used consistently throughout the schedule.
An important event, such as a ground-breaking ceremony or receipt of occupancy from the building inspector, is called a milestone. A milestone has no duration or resources. It is simply an indicator of an important point in the project.
Resource Allocation and Calendars
A common resource constraint is availability. To consider the availability of team members, consultants, and key pieces of equipment, you can create a resource calendar for each that indicates which days are available and which are days off for a group, an individual, or a project asset such as a piece of important equipment. A calendar for team members from the same company could be the company calendar that shows working days, weekend days, and holidays. Individual team members can have individual calendars that show their vacation days or other days off, such as parental leave days. If major pieces of equipment are only available for certain periods of time, they can be given a resource calendar. Resource calendars become important tools when changes must be made to the schedule. When a resource calendar is applied to a duration estimate, the duration in days is distributed across the available calendar days. For example, if the duration is three days and the start date of the activity is Thursday, the activity would begin on Thursday and end on Monday of the following week, assuming the resource calendar shows that the person has the weekend off. If the weekend included an extra day off for a holiday like Labor Day, shown in the calendar in Figure 8.6, the completion day of the same three-day activity would be pushed to Tuesday.