Theory of Constraints Handbook - James Cox Iii [98]
Efforts to improve the project system of systems must address the waste that slows task accomplishment, wastes our limited resources ’time, and increases the costs in projects. Waste comes from two main areas. The first area of waste can occur during planning; whether through identifying the wrong tasks or arrow dependencies; incorrect assigning of resources to a task; missing tasks, or incorrect or incomplete customer requirements. The second area of waste occurs during the execution of the project from the misalignment of priorities, misuse of limited resources, or misaligned behaviors. We address waste issues within the project plan during project planning and scheduling. We address waste in project execution with the alignment of the system of systems.
What is waste in a project environment and will I know it when I see it? Dr. Taiichi Ohno (1988) identified seven categories of waste (to which an eighth category has recently been added). Many of the definitions for these categories are manufacturing based and not project based—yet the categories are very powerful to drive out waste, create speed, and increase capacity in the project environment. These categories are translated as follows.
Categories of Waste in a Project Environment
The first category of waste is overproduction. In the project environment, this can translate into starting a path or task before it is available to start or assigning resources to any task because you have the resources and not because there is a task needing that resource or that quantity of resources. Additionally, overproduction might be seen as doing a task as part of the project, when in fact it is not part of delivering the value of the project.
Figure 6-8 depicts an example of what was planned versus how it was executed. The organization ends up spending additional time on a task, more than was needed, and tying up resources longer for no additional value or speed.
The second category of waste is waiting. Since productivity should be defined as how fast we complete a task and hand it off, then when a task is interrupted and waits for a resource that is pulled away to work on other tasks at the same time, the task experiences waste in the time it waits or is idle while the resource works on another task. This is often the case when a resource is multitasked (Fig. 6-9).
Another example of waiting occurs when a predecessor task completes its work, but does not pass on that work to the successor task. The successor task experiences waste by waiting for its handoff.
The third category of waste is transportation. Transportation waste in projects occurs when an incorrect predecessor–successor task dependency is identified, resulting in an unnecessary delay waiting for a predecessor task to be completed for an input that is not necessary for the successor task to start. Another example is when a review that generates a “looping” back or rework loop is later in the process than it should be, lengthening the project’s overall time by the time it takes to redo the earlier tasks.
FIGURE 6-8 Overproduction. ©1991–2010 Avraham Y. Goldratt Institute, LP. All rights reserved.
FIGURE 6-9 Waiting during multitasking. ©1991–2010 Avraham Y. Goldratt Institute, LP. All rights reserved.
FIGURE 6-10 Transportation: Reviews in the wrong place. ©1991–2010 Avraham Y. Goldratt Institute, LP. All rights reserved.
Figure 6-10 shows a medical review of internal requirements needed to meet customer requirements for a specific drug trial occurring after the time-intensive costing process. This review could be done early in the process prior to the more time-intensive tasks, shortening the quantity and time investment of tasks that might need to be reworked.
The fourth category of waste is excess inventory. In a project environment, excess inventory is represented by elements of too much task work in progress, or resource/resource groups