The Last Planner System (LPS) is a production planning method from lean construction, developed by Glenn Ballard and Greg Howell and promoted by the Lean Construction Institute. Its central idea is that the "last planners", the foremen and trade supervisors who direct the work, plan it together and commit only to tasks that are ready to be done. Progress is measured by how many of those commitments are kept each week.
At a glance
| Origin | Lean Construction Institute, 1990s |
| Levels | Master schedule, phase (pull) plan, look-ahead, weekly work plan |
| Key measure | PPC (percent plan complete): commitments kept ÷ commitments made |
| Who plans | Trade foremen and supervisors, together |
| BIM link | 4D views of the look-ahead and the constraints |
The parts
- Master schedule: the milestones, as usual.
- Phase planning (pull planning): working backwards from a milestone, trades place the tasks they need from each other on a wall or board, agreeing handoffs.
- Look-ahead planning: tasks for the next few weeks are screened for constraints (drawings, materials, access, permits) and those constraints are removed in time.
- Weekly work plan: each trade commits only to tasks that are free of constraints.
- Learning: missed commitments are recorded with a reason, and the reasons are tracked over time.
How it is used on projects
LPS is used on sites of every size, often on a physical board in the site cabin. Models help in two places: in pull planning, where a 4D view of a zone makes the sequence and the handoffs visible, and in the look-ahead, where the model shows which design information or which prefabricated parts are still missing. Constraint logs can be linked to model elements so that the coordinator sees what is blocking the site.
Variations
- Board-based with sticky notes, one colour per trade.
- Digital LPS tools, sometimes linked to the programme and the model.
- Takt planning, a related lean method that sets a fixed rhythm for work moving through zones.
Common misunderstandings
- "It replaces the programme." The master schedule remains; LPS manages the work within it.
- "A high PPC means the project is on time." PPC measures reliability of weekly promises, not progress against milestones.
- "The planner fills in the weekly plan." The point is that the people doing the work make and own the commitments.
Where to read more
The Lean Construction Institute's material on the Last Planner System; Glenn Ballard's published thesis and papers; the lessons on reading a programme and 4D on this site.