Why is a large construction project handled differently than a small project such as a family home? The answer is simple: it is much more complex. Therefore, for large projects, a single project management system or a lean system such as Glenn Ballard's Last Planner® System (LPS) is not enough. To achieve flow efficiency throughout the construction project, several lean systems need to be set up and then linked together. A system is a definable entity made up of different components that have an orderly relationship with each other and together form a complex whole. If several lean systems are coupled, a new, more complex system is created, the multi-lean system.

What is a lean system?

A Lean system has clear boundaries that need to be defined in each project. The boundaries depend on the complexity of a project. There are projects whose process can be presented clearly and concisely and others that have to be divided into small process chains to remain manageable. The processes are usually not as straightforward as they are presented in the classic critical path method (CPM). There are various interfaces that need to be linked together. Lean strives for flow efficiency and this can only be achieved if all interfaces in the process between the different actors in the system are considered and linked together.

What are the goals of a lean system? The main goal of a lean system is to achieve flow efficiency. The following sub-goals can be derived from this (Figure 1):

- Reduction of complexity
- Improved exchange of process owners
- Forward planning
- Integral view of the project
- Commitment of the process owners
- Common understanding of the project
- Improved collaboration
- Improved communication

Figure 1: Objectives of a lean system. Graphic: Refine Projects AG.

What are the prerequisites for a lean system?

To achieve flow efficiency for the construction project, a set of different artefacts is needed. Artefacts mean results of a work process. These are Project milestones, Overall Process Analysis, Milestone & Phase Plan (Look Ahead on weekly basis), 6 Week Look Ahead (on daily basis), Improvement Management with KPIs and a Action Plan and Risk Matrix.

Figure 2: Refine set of Lean Artefacts. Graphic: Refine Projects AG.

What are the differences in coupling these Lean Systems?

A multi-lean system is created by coupling several lean systems. Two basic forms of coupling can be distinguished: Series connection or parallel connection. Put simply, in construction projects where a relatively large amount of work takes place sequentially, a series-connected multi-lean system is more likely to be used, and in projects where a lot of parallel work takes place at the same time, for example, construction is taking place on different floors at the same time, while interior work has already begun within the floors, a parallel-coupled multi-lean system is more likely to be considered. In practice, however, the selection of the appropriate coupling type is somewhat more complicated.

It depends on various factors, e.g. the following questions:
- At what stage is the project?
- Is the design ready?
- What is the organisational structure of the project?
- What experience does the project team have with Lean Construction?
- How many types of use are there? (for example, offices, recreation rooms, production halls, etc.)
- Complexity (division in order to gain clarity.

How does the flow of information work with the different couplings?

Clear system interfaces are needed for series connection. The lean systems are secured and coordinated by the lean manager. His task is to manage and transport the interfaces and the flow of information.

Parallel lean systems require a superordinate system for the coupling of information. Here it makes sense to install a superordinate big room. There, the project management has access to the essential project issues that require action and the issues arising from the subordinate systems can be processed transparently.

How do you go about setting up an overarching multi-lean system?

As part of refine's consulting activities, we advise clients on setting up multi-lean systems and accompany them as lean coaches through the entire process from project design (lean design) and construction (lean construction) to project commissioning (Lean commissioning) handover.

When setting up the overarching Lean system, refine follows a similar approach to that of an LPS: OPA, MPP, 6WL and subsequent weekly Production evaluation and planning (PEPs) meetings are the Lean artefacts that are already familiar from the LPS: The design phase starts with the overall process analysis (OPA) and the milestone and phase plan (MPP). This delineates the system and defines the important milestones for the success of the project. This is followed by the 6-week Look Ahead (6WL). In this preview, the different phases of the project are planned in more detail on a daily basis. This also clearly defines the interfaces between the different activities. With the help of risk matrix and key performance indicators, the risks, progress and developments of the project can now be recorded. Key activities are defined in the action plan to ensure that delays and waste are prevented.

Figure 3: Exchange of issues and topics between 3 Lean Systems. Graphic: Refine Projects AG

In addition, the various systems make an important contribution to keeping the tracking of progress by means of the schedule up to date. For this, strict networking of the milestones is indispensable. A decisive success factor is above all uniformity; each system must provide the same information. This can be ensured through a uniform approach by system coaches, such as the refine experts.

What are the roles in a lean system?

Before defining the tasks in a Lean system, the roles must first be defined. At the highest level is the project manager, who is responsible for the economic and operational success of the project. He uses the project management methods and defines the mission of the project. At the next level there are the technical planners or technical specialists, who are often supported by site managers on the part of the project management team. By introducing Lean Design and Lean Construction in a construction project, a transformation process occurs that is accompanied by so-called Lean specialists. They take on a neutral role as facilitators and coaches and do not pursue their own project interests. This relieves the capacities of construction management or site management in particular. With the help of the multi-lean system, all relevant process owners are involved and thus fluent and transparent communication is achieved across all levels. Short-cycle weekly product evaluation and production planning meetings (PEP) create a high level of identification with the project. Faults can be identified and eliminated immediately. In this way, the milestones always remain present and the overall completion date is secured.

What is the added value of multi-lean systems?

The added value of multi-lean systems is that the construction project is always considered holistically while maintaining the right level of detail. No two multi-lean systems are the same, but are developed in consultation with the client for the specific construction project. It can be adapted at any time if conditions change or new insights are gained. The ultimate goal is the successful completion of the project within the given time and cost frame.

Further reading

Nesensohn C. & Pitterle J. in: Mauerhofer, G. (Ed.) (2020). Lean Baumanagement: Erfahrungsberichte aus Praxis und Wissenschaft - Band 1.

Ballard, Glenn (2000). The Last Planner System of Production Control, Ph.D. Dissertation, University of Birmingham, UK.

Fiedler, Martin (ed.) (2018). Lean Construction - The Management Book. Agile methods and lean management in construction. Springer Gabler, Wiesbaden.