Many people are interested in the Japanese state of Lean Construction because Lean Construction has been born out from the Toyota Production System (TPS). Although I have been studying and introducing Lean Construction for some years, even now people who know the term "Lean Construction" seem to be less than 50 in number inside Japan. Outside Japan there is not so much information about the Japanese state of Lean Construction, which this contribution is aimed at presenting.
What is Lean Construction?
The first problem in introducing Lean Construction in Japan is that its definition is not clear. The definition here is as follows: Lean Construction is the management concept to: 1) evaluate the current state - discover problems, 2) improve by such tools as 5S or LPS, and 3) repeat the evaluation and improvement on a daily basis.
After all, Lean requires continuous improvement and evaluation. I propose that the main improvement tools can be divided into 3 groups: basic, intermediate, and advanced tools.
The basic tools:
1) Elimination of waste (Recognize the seven definitions of waste and eliminate waste)
2) 5S (Seiri, to distinguish between what is necessary and what is not)
3) Visualization (Visualizing problems)
The intermediate tools:
4) Procedure improvement (Doing procedure improvement with simple solutions before facility improvement)
5) Information sharing
6) Improvement by all (Improvement by all engineers and workers).
The advanced tools:
7) Saving labor (replacement of workers by saving labor at the workplace)
8) Multi-operational (Workers able to do multi-operations)
9) PAB (Production Analysis Board or a display to show actual performance compared with planned performance)
10) Kanban (Kanban is a card informing of the order or of the quantity which is used)
11) Just-in-time (It is to deliver what is needed and when it is needed)
12) Standardization (Standardization of work)
13) Leveling (Leveling of work lot and production）
14) Information-and-communication technology application
Lean Construction is a management concept to stimulate and sustain motivation of on-site engineers, not just one fixed method. As a metaphor, Lean Construction is the stage of an opera whereas tools are individual actors. In terms of personal computers, Lean Construction is the operating system whereas tools are application software.
The Toyota production system (TPS) covers all the tools except the last one -- Information-and-communication technology. The Last Planner System could be thought of as a new tool combining Information Sharing and Production Analysis Board.
Lean construction in Japan
Not limited to the construction industry, many Japanese companies are not conscious about the name of Lean or TPS. They are executing information sharing and to some extent implementing elimination of waste and 5S.
In the past, some general contractors challenged to apply Lean Construction, tried to focus on PAB tools which are considered very important in Toyota’s factories. The rather unsuccessful results are partly because the workers became resistant to Lean Construction due to the increase in workload of applying PAB in a strict and short-periodic way. Additionally, the nature of the construction work which is different from site to site makes it difficult to make step-by-step improvements.
When engineers individually apply Lean tools, they mainly use such tools as elimination of waste, 5S, visualization, and procedure improvement tools. There are many success stories among them. However, there is limited accumulation of knowledge because individuals have a difficult time using the same kind of improvements in many different sites.
Recently an exceptional lean success story has been reported from a company specialized in painting road-lane markers called "Hokkaido Giken". It is easier to accumulate ingenuity because such a specialized company has repeatable work and it is easier to make improvements step-by-step. They use kanban, visualization, and combination of process improvement and simple PAB.
A better way forward
From the lessons learned in the past and present Lean Construction in Japan, here are some suggestions moving forward.
Passion and motivation are indispensable for the promotion of Lean. In order to maintain motivation, it is necessary to embrace something more than making bigger profit like the idea to make all of the employees, the clients, and the company a bit better every day.
Importance of Evaluation
In the experience up to the present, "what to do" has been paid more attention to than "how to do it". When applying Lean to other industrial fields besides Toyota, it is necessary to think about not only what to do but also how to do it as well. The evaluation of Lean Construction is itself asking "how to do it". Similar to the improvement tools, there are many tools in the evaluation process including:
1) Problem finding
2) Standardization of evaluation (Making the standard with which they evaluate, such as setting of the target cost)
3) Visualization of results (Visualization of improvement results such as acceptance of the idea, praise, reward, and award)
These are all part of TPS. What we call "Lean culture" seems to have a lot to do with "how to do it".
Initial Step and Advancement
It is better to start with the basic tools of the improvement process and to start in a specialized field where it is easier to accumulate ingenuity. If there is a clear problem and a specific purpose to solve it, advanced tools can be used. In applying Lean in the construction industry, we should select suitable tools and suitable kind of works.
It is one thing to succeed in realizing the true potential of Lean Construction and another to sustain it. Using Lean, it is important to constantly drive forward and make the world a little better each and every day.
 Inokuma, A.(2014), Absence in the Provenance? Lean Construction and Its applicability in Japan, Proceeding IGLC-22,15-26