By Mark McKenzie on Aug 12, 2019 8:00:00 AM
The term pull planning is being used more and more in construction planning and scheduling. Where did the term originate from? What does it mean exactly? What does pull planning replace? What are the benefits?
The origins of pull planning
The Lean Construction Institute (LCI) and its founders Glen Ballard and Greg Howell certainly deserve the credit for their work in suggesting that the concepts of the Pull System or Just in Time (JIT) used so successfully in manufacturing could be applied to construction projects to improve scheduling reliability.
Although there are some conflicting accounts of the origin of the pull system, Toyota’s Taiichi Ohno is considered to be the “Father of JIT” (Just-In-Time). Implementing the Kanban pull system was a result of Toyota’s fascination with American supermarkets and general inventory management (when a customer pulls an item from the shelf, a signal is sent to replenish the item).
Nicole Radziwill, in her article The Origins of Just-In-Time, describes how Toyota adopted this system when she says, “This (the supermarket system) was the genesis of the Toyota Production System (and sometimes elusive) socio-technical system for production and operations. This approach bridged the gaps between production and continuous improvement and became the basis for lean manufacturing as it is known today.”
Pull planning and the Last Planner System
In this video, LCI co-founder Greg Howell describes his experiences and research that led to the founding of LCI and the development of Last Planner™ System. The goal of the Last Planner system is, as Greg states, “Predictable work flow and rapid learning.” This is accomplished by utilizing a milestone master schedule, a short interval scheduling process designed to remove all constraints, and capturing reasons why, when plans are not achieved.
The LCI in their terms glossary provides the following definitions of “Pull” and “Push.”
“Pull” – A method of advancing work when the next in line customer is ready to use it. A “Request” from the customer signals that the work is needed and is “pulled” from the performer. Pull releases work when the system is ready to use it.
“Push” – An “Order” from a central authority based on a schedule; advancing work based on central schedule. Releasing materials, information, or directives possibly according to a plan but irrespective of whether or not the downstream process is ready to process them.
Push and pull planning in construction
For those of us who have been involved in larger complex projects, the idea that a scheduling technician can create a Master Schedule down to the Work Package level before the project starts, and that’s how the project will actually be executed, is not plausible. This would be an example of the “push” method of scheduling.
We tend to talk about projects that didn’t go well. Projects with poor productivity, cost overruns, schedule slippages, disputes, etc. I have been fortunate to be involved, more times than not, in numerous very large, complex industrial projects, with demanding owners that were completed with great safety records, ahead of time, with very happy customers. As an added bonus, we made or exceeded our bid margins.
The common thread with all of these successful projects was a commitment to detailed planning, using short interval scheduling (rather than the push method described earlier). First implemented by The Industrial Company (TIC) in the early 1980s, short interval scheduling was a piece of paper where the frontline supervisor (with help from superintendents) would list the tasks they planned to do the next week and the manpower required. In the comment section, they would list their needs (material, equipment, tools, area releases, etc.). The project manager, superintendents, and planners would review these schedules and needs, resolve conflicts, provide redirection if needed, and do everything possible to make sure the crews had what they needed, before the work began. It worked pretty well.
In my days in construction, we found that short interval planning with collaboration and follow up, was critical to have any chance of staying on schedule and managing our labor costs. That’s why we made it a cornerstone of our labor management software.
Trestles’ mission is to leverage our experience and the research that these great institutions have completed. Our goal is to provide frontline supervisor training and short interval scheduling technology that can be quickly and inexpensively implemented. Standards are great, but when it comes to your company, it is not a standard until everyone is using it.