Last Planner System (LPS)
A lean planning system that makes the people doing the work responsible for the plan.
Quick Answer
The Last Planner System (LPS) is a lean construction planning method in which the people who directly supervise the work plan it collaboratively. It links master scheduling, phase pull planning, make-ready look-ahead planning, and weekly work plans. Teams track the share of weekly commitments completed, called percent plan complete, to improve plan reliability over time.
The Full Picture
The Last Planner System exists because traditional construction schedules describe what should happen, not what can happen. Crews show up to work that isn't ready: the upstream trade isn't finished, the material hasn't arrived, the RFI is unanswered. Glenn Ballard and Greg Howell developed LPS in the 1990s to shift planning toward the 'last planners', the foremen and superintendents who assign the work, and to shield crews from work that isn't ready.
Mechanically, LPS works at several levels. The master schedule sets milestones. Phase schedules are built through pull planning to show how each milestone will be met. A six-week look-ahead screens upcoming activities for constraints (design information, materials, equipment, prior work, labor, permits) and assigns someone to remove each constraint. Weekly work plans contain only activities that are ready, and each trade makes a commitment it can keep.
Each week the team measures percent plan complete (PPC): the share of committed tasks actually completed. When a commitment is missed, the team records the reason. Over time, those reasons show where the planning system is failing, such as late design information or unreliable deliveries, so the team can fix root causes instead of pushing crews harder. The Lean Construction Institute promotes LPS as the core production-planning practice of lean construction.
In preconstruction, LPS matters because many of the constraints that stall field work are created or resolved before mobilization: incomplete design, long-lead procurement, and permits. Teams on IPD, design-build, and CM-at-risk projects often apply LPS to design and procurement work itself. Common failure modes are treating the weekly meeting as a status report, allowing activities onto the weekly plan before constraints are cleared, and tracking PPC without acting on the reasons for misses.
Real Examples
Common Misconceptions
People assume: The Last Planner System is a scheduling software product.
Actually: LPS is a planning method and a set of routines. It can be run with sticky notes on a wall or in software, but the value comes from the collaborative commitments and constraint removal, not the tool.
People assume: A high percent plan complete means the project is on schedule.
Actually: PPC measures how reliably the team keeps its weekly promises, not whether it is ahead or behind the master schedule. A team can hit high PPC while committing to too little work, so PPC is read alongside milestone progress.
Frequently Asked Questions
What are the main components of the Last Planner System?
The commonly described components are master scheduling, phase scheduling through pull planning, make-ready look-ahead planning with constraint analysis, weekly work planning with reliable commitments, and learning through percent plan complete and analysis of reasons for missed commitments.
What is percent plan complete (PPC)?
PPC is the number of weekly commitments completed divided by the number made. It measures planning reliability. Teams track PPC over time along with the reasons for misses to find and fix the root causes of unreliable work flow.
Who are the 'last planners'?
The last planners are the people who assign work directly to crews, typically trade foremen and superintendents. LPS places planning responsibility with them because they know what their crews can actually accomplish and what they need to start.
How does the Last Planner System differ from CPM scheduling?
CPM scheduling calculates durations, logic, and the critical path for the whole project. LPS is a production-control system that manages how work is made ready and committed week to week. Most lean projects use a CPM master schedule and run LPS beneath it.
Is the Last Planner System only for field work?
No. Teams apply LPS to design and preconstruction as well, pull planning design deliverables and tracking constraints like owner decisions, permit reviews, and long-lead procurement.