Thoughts on planning versus scheduling

We talk a lot, at Actenum, about the application of our optimization technology to planning and scheduling situations in asset-intensive industries. I often use both terms in conversations with others without making any formal distinction between them. Yet there are important differences, and so some explanation is in order.

Both planning and scheduling are concerned with the allocation of resources to tasks that need to be performed, over some period of time (the word “tasks” can be replaced by “activities” with identical meaning). So, what we deal with at Actenum is focused on strategies and tactics for the allocation of equipment or people—over time—to execute tasks required to achieve some end (for example, to allocate drilling rigs to possible oil or gas wells, or to accomplish a set of preventive maintenance tasks in a production environment).

The difference between planning and scheduling is not always clear cut. But in general, planning deals with longer time horizons (months or years) and is usually more strategic: it’s concerned with high-level decisions, such as where to build a processing facility, or what production levels are appropriate or required in a given period. Scheduling, on the other hand, is more focused on the short term (hours, days, or weeks), and the emphasis is usually on tactically-oriented lower level decisions, such as the sequencing of operations. As well, in planning, maximizing profit is often important, while in scheduling, the emphasis tends to be on finding ways to accomplish a series of tasks at minimum cost or in the shortest time.

My explanation above isn’t perfect. At the same time, it serves as a useful starting point for some observations about how planning and scheduling are linked in typical complex production organizations. I’ll save that discussion for a later post.