Just 20 years ago, open communication between the trades and management about day-to-day work was not the norm. Herman Ballard wrote in his Ph.D. thesis, “The Last Planner System of Production Control,” it is essential to base the plan for the project on the requests, or pull, of those who will be the last to complete their work, starting at a target completion date and moving backward.
Ballard shared his ideas with Gregory Howell, an engineer, and in 1997, the two formed the nonprofit Lean Construction Institute.
“They started the institute as a way of sharing the Last Planner system [LPS] …lean construction and other approaches to improve the industry,” said Kristin Hill, director, education programs, the Lean Construction Institute. “The approach called pull-planning is an overarching principle used throughout the levels of the Last Planner system with the mission of improving the project and ultimately leading to transforming the built environment through lean implementation.”
The LPS uses five levels, or conversations:
While a project starts with broad strokes in the milestone planning phase, as the project proceeds, the conversations focus increasingly on the details.
“At the weekly work planning level, those involved are making commitments to do the work and then managing those commitments,” Hill said.
Today, some contractors are embracing the LPS, in part because of its conversation-based approach.
“Any issues or items that need to be completed beforehand are discussed along with decisions about how much time is needed to perform the tasks, so that a start date can be determined as to who needs to go first, second, third and fourth,” said Rick Trocano, vice president of business development, Sequoyah Electric, Redmond, Wash. “The process considers what the different trades need in terms of space and time to complete their specific installation. Obviously, each trade needs to get their rough-in installed in a timely manner, but that cannot always happen while working together shoulder-to-shoulder with other trades at the same time.
“Typically, the plumbers/sprinkler come first, then the mechanical, followed by the electricians, and then the low-voltage/fire alarm trades. Each trade gets their turn in a space to work efficiently. Otherwise, you would have trade stacking, where everyone is working on top of each other, which obviously is not as productive, and, in addition, we electricians must avoid certain equipment and materials being used by other trades, for example, temporary power setups.
“Essentially, if we don’t have a clear, reasonable access to our work, we must stay busy doing something else and then come back multiple times to do an installation that should have been completed in just one pass. Last Planner system provides a better way. The basic idea of it is that, to finish a certain goal or milestone at a certain time, it’s recommended that the conversation with the construction team start by a discussion of what needs to be done to achieve that finish date, then work backwards from there in planning,” Trocano said.
Basically, the question asked at construction team meetings is: “What needs to be in place for the last contractor on any part of the project to complete their project?” In answering that question, the construction team—made up of everyone from the GC to the architect to all the major subcontractors—point out what would stand in the way of that last contractor and how they could clear the way.
“Working backward helps you determine specific milestones that need to be accomplished to continue an even flow of the project. It prompts the team to scrutinize the project process more carefully,” said Robert Bennett, project development manager, Morrow-Meadows Corp., City of Industry, Calif.
The construction team discusses and solves the ensuing problems based on the belief that the voice of everyone involved in a construction project is important.
“A scheduler might sit down and come up with milestones and work backwards, but doing it in a vacuum is a different dynamic,” Hill said. “At each level of LPS, the team of contractors are developing a network of commitments and managing those commitments, looking at them and alerting the team if there’s a constraint that needs to be removed so that the commitment can be met.”
For example, as a visual way of tracking and managing tasks, the team could use color-coded sticky notes on a board—one color for electrical, another for mechanical, etc. As the production team discusses work stages and discovers any tasks that aren’t possible to complete that week, the sticky note regarding that task is moved to another spot on the board. For instance, if a mechanical contractor reports an AC unit that was scheduled to be installed on a certain date will not arrive until a month later, the board can be rearranged ahead of time. Instead of waiting for a future logjam, the team can plan accordingly and save time.
“Another aspect of lean construction is integrated lean project delivery [ILPD], a way of organizing for teams to optimize value on projects,” Bennett said. “When you’re using ILPD and include Last Planner system, it helps because you can hit the dates and manage costs more effectively. Typically, we use ILPD and Last Planner system for design-build more often than not, because it’s a good way to start. You have an end date, and you work your way back.
“Compare it with the way we used to do things. We’d start with a project schedule, building forward towards the end product. Delays could be ongoing. On some projects, we ran into a lot of problems if the architectural portion of the building was not fully designed per the performance documentation. For example, on one project, the architect was still moving walls around, which meant that the mechanical, electrical and plumbing [MEP] couldn’t finish ahead of or on schedule because of those moving walls. On a project using the Last Planner system, the building footprint is ‘locked down’ to properly release work by the MEP team. The end date could slip a lot easier than if you’re using the system. You design backwards, making sure you have all your processes in place to make that end date. Everyone on the team has certain tasks that they must do by certain dates, which makes everyone more accountable.
“The Last Planner system also works well with design-build as opposed to design-bid-build,” Bennett said. “With design-build, responsibility for the pace of the project is shared by all of those involved. The foundation of the building—digging all the duct banks—and all the utilities are being dug into place while we’re designing.”
ECs can use LPS to work backward and give themselves the stretch of time they need to complete each portion of a job without wasting time, money or materials.