Theory of Constraints Handbook - James Cox Iii [53]
Because multitasking is rampant in multi-project environments, and generally is highly valued by management, we wish to stress again its negative effect on productivity. So that you can experience the harmful effects of multitasking, we have included a “Wafer Experiment,” located at www.mhprofessional.com/TOCHandbook that you should conduct. The experiment compares traditional multitasking on three projects with the CC approach. This is a nice experiment to perform with your children, who may be far better than you may be at manipulating objects on a computer, and who will benefit from being involved in the experiment.
Establishing Project Priorities
It is beyond the scope of this chapter to solve all the problems of prioritization, but it is imperative for every organization in a multi-project environment to use some priority scheme. It does not make sense to permit, by default, the setting of priorities by a resource manager or other person who may not have a global perspective of the organization’s many ongoing projects.
Many organizations have established a Project Management Office (PMO) for the management of their project portfolio. Some of the possible functions of a PMO are described in Fig. 3-7. Notice the establishment of project priorities based on business priorities, resources, and organizational skills.
Selecting a Scheduling Resource and Establishing Scheduling Buffers
Once project priorities are established, the key TOC concept of buffers can be employed to control the initiation of new projects. In a multi-project environment, each project is scheduled in the same way as in a single project environment, but without regard to resource usage in other projects. Due to massive task duration uncertainty, it is not possible to level all resources across all projects and expect such initial leveling to remain effective for any period of time once project execution is begun.
In order to minimize the need for resources to multitask and to make sure delays on one project do not affect other projects, entry of new projects into the system must be controlled. We have chosen to use the descriptive terms of “scheduling resource” and “scheduling buffers” in this chapter to restrict the entry of new projects. However, standard terminology has not been established. A search of CC software vendors’ training materials and an investigation of materials and resources used by consultants, academicians, and other CC experts have yielded references to “pipeline buffer,” “staggering buffer,” “drum feeding buffer,” “scheduling resource buffer,” “synchronizing buffer,” “drum buffer,” “sequencing buffer,” “capacity buffer,”20 “drum schedule buffer,” “pacing buffer,” and “capacity constraint buffer.”
FIGURE3-7 Functions of a Project Management Office. (Reprinted with permission from A Practical Guide to Earned Value Project Management, 2nd ed., Charles I. Budd and Charlene S. Budd. © 2010 by Management Concepts, Inc. All rights reserved.)
A scheduling resource (SR), somewhat similar to the constraint resource in Drum-Buffer-Rope (DBR) implementations for manufacturing, is used to minimize resource conflicts and prevent choking the organization with too many projects. Just as material is scheduled into a production line based on the system’s constraint (the drum that controls the pace of production), we can schedule the initiation of projects into our operations based on the scheduling resource’s availability.
Of course, identifying a resource constraint in most multi-project environments is impossible and unnecessary. Therefore, choosing the “right” SR is not critical, but the SR should be one that is utilized across most projects.