Pull Planning Confusion

Many people misunderstand pull planning, a central practice in the Last PlannerĀ® System. It stems, in part, from an unfortunate characterization that some early LPS practitioners made. They called pull planning “reverse phase scheduling.” That name only tells one small part of the story.

The purpose of pull planning is to design a project-based production system in conformance with lean principles. Like all aspects of Last Planner, it is a collaborative approach that includes those who are directly responsible for supervising the work on the project. People mistake merely scheduling a phase of work from the end working backwards for the intent of pull planning.

Another problem I see is that people are focused on the wrong things. Some people take great care in getting all the data elements on a sticky note. But you have to use the correct data and use that data correctly. Just the other day I saw a series of stickies with “activities” versus “conditions of satisfaction” (COS) and “durations” rather than “concentrated effort”. These are major mistakes in understanding. People can’t do the work of designing a lean production system without the correct data. Some people say why does this matter? I can explain.

Let’s say that we want to bake a pie. The recipe for the crust calls for a 1/4 cup of white crystallized granules, a cup of white powder and a stick of white sticky stuff. Is this an adequate description of ingredients for making pie crust? Do we use sugar or salt? Do we add powdered sugar, flour, baking soda, baking powder or corn starch? Do we mix them with lard, vegetable shortening or marshmallow fluff?

Vocabulary matters because the distinctions we make in language matter to the actions we will take. Substituting the word “activity” for “conditions of satisfaction” puts the attention on the action rather than on the outcome. One of the keys to the design of the production system is clear conditions for handing the work off from one performer to the other. We call those “conditions of satisfaction,” not “activities.” Similarly, we want to know the concentrated effort to fulfill the conditions of satisfaction which is the elapsed time to perform for specific people who are performing, e.g., 10 hours for 1 licensed mechanic and 1 apprentice. The team needs this information so they can adjust crew sizes and batch sizes across the whole project to design for flow.

You won’t get pie crust from adding any three white things together just like you won’t get a lean project by working only with activities, durations and scheduling backwards. To borrow a principle from Choosing By Advantages Decision making, you must learn and skillfully use the pull planning method to create flow on your project.

There is more to pull planning than I can cover in this blog post. Look for other lessons in the Pull Planning Primer.

Comments

It is important to remember that a pull plan is not developed and enacted in a vacuum. The reason we call it a “reverse phase schedule” and the reason that is a more descriptive term is that we are isolating phases within the master schedule and then adding more detail via a backward pass from a defined milestone. We continue to add more detail in a look ahead schedule derived from the reverse phase schedule which then progresses into the day-by-day description of the work known as a weekly work plan.

The pull plan is not a separate piece of the puzzle, but rather a step in the planning process in which detail is added based on collaborative input from the trade partners.

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