Part 1
Lean Construction themes
1 Theory of Lean Construction
Lauri Koskela
1.1 Introduction
Lean Construction is the counterpart to Lean production (or just Lean as a noun), as it has evolved in the context of construction. Lean is mentioned as one of the world’s most influential management ideas (Buchanan and Huczynski, 2016), and as one of the most influential manufacturing paradigms of recent times (Holweg, 2007). What then explains the superiority of Lean? Strangely, the literature has little to say on this question, and the scattered remarks that can be found are often contradictory.
Against this backcloth, and as one of the major functions of a theory is to explain, this chapter endeavours to present a consolidated discussion on the theoretical (and philosophical) foundation of Lean and its instantiation in a particular context, such as construction. The treatment is predominantly based on the author’s research into this topic since 1991. Due to space limitations, only the most important, high level concepts are treated here.
For several reasons, the topic to be discussed is complex and multifaceted, and thus a fair number of questions have to be discussed: Is there a theory of Lean, in the first place? Is a theory of Lean needed? If we are looking for the theory of Lean, what are we after? What is the mainstream theory of production management? What then is the theory of Lean? How is Lean Construction different from Lean production?
1.2 Is there a theory of Lean, in the first place?
According to the Japanese scholar Fujimoto (2007), the Toyota Production System (TPS) ‘emerged as the unplanned and unexpected result of … seemingly unrelated innovations, improvements, and initiatives’. This emergence is compatible with the popular view of Lean as a set of practices, which can be bundled into four areas (Shah and Ward, 2003): just-in-time, total quality management, total productive maintenance and human resources management. In a similar vein, Fujimoto (2012) states that the TPS consists of 400 organisational routines. This would indicate that there is no or little theory underlying Lean, which would seem to be just a collection of unrelated practices or routines. However, as the author of this chapter has repeatedly argued (Koskela, 2000; Koskela et al., 2018; Koskela, Tezel, and Patel, 2019), the theoretical and philosophical foundations of Lean can be pinpointed and also the origins of the different theoretical ideas can mostly be determined.
Why, then, has the theory of Lean failed to surface? There are two main reasons; one is related to the Japanese origin of Lean, and the other to the dominant understanding of management research. The Japanese culture tends to emphasise direct personal experience (Nonaka and Takeuchi, 1995) rather than abstract theories. In alignment with this orientation, the Toyota Production System has not been based on explicit theoretical knowledge, and it is taught to new employees through socialisation (Yadav et al., 2017), rather than through theory-based education. Thus, no or little theory has emerged from Toyota.
One of the central tasks of management research is to decode the theoretical foundations of a management invention created in companies (David and Hatchuel, 2007). It is indeed surprising that the community of management scholars has not succeeded in creating a settled view on the theory of Lean. Here, the explanation is historical. Management research has been decisively influenced by two books published in 1959 (Gordon and Howell, 1959; Pierson, 1959), outlining the contents and objectives of such research. In this conception, production was – just – an application context for managerial methods rather than an object of research (Koskela, 2017). This meant that production, as a phenomenon to theoretically embrace, was thrown out of the domain of management. As Lean arguably is a theoretical innovation in the field of production, the discipline of management has not had access to concepts and principles which are at the heart of this innovation.
1.3 Is a theory of Lean needed?
But even if the theory of Lean could be determined, the question can be raised whether we need such a theory. Namely, Lean production is a generalisation of the Toyota Production System (TPS), which was developed and is still successfully applied without any underlying theory (as discussed above). In turn, Lean production has been applied in countless new contexts, again without the support of a theory.
What indeed would be the role of theory if Lean has been successfully developed and applied without it? Here, general arguments about the many useful functions of a theory, both in research and practice, could be forwarded: explanation, prediction, giving direction, possibility of testing, etc. (Koskela, 2000). However, perhaps a more persuasive argument can be found just by looking at how Lean production is understood by neighbouring disciplines to management.
Let’s first consider recent textbooks on organisational behaviour (Buchanan and Huczynski, 2016; Knights and Willmott, 2016; Martin and Fellenz, 2017). As Lean extends to organisational behaviour (for example Liker, 2004), it is of interest to find what they say about Lean. The two first books discuss Lean, even with some enthusiasm, but the third only mentions it in a few sentences without any substantial discussion. As mentioned above, Buchanan and Huczynski (2016, p. 467) state that Lean has become one of the world’s most influential management ideas, and characterise it as follows:
TPS’s aim is constant improvement, and reduction in costs through the systematic elimination of waste using the assembly line system.
In turn, Knights and Willmott (2016, p. 540) define Lean production as follows:
It is associated with just-in-time services and stock inventories where companies do not retain excess labour or stocks of goods but use information technology to ensure recruitment or reordering of stocks when actually needed.
Of course, both the assembly line system and information technology are incidental to Lean. It turns out that the two textbooks discussing Lean cannot explain it.
Let’s then turn to current textbooks on economics. According to Samuelson and Nordhaus (2005), economics is the study of how people and society choose to employ scarce resources that could have alternative uses. Thus, decisions under scarcity is the focus of economics. Lean would seem to offer a radically new idea in this context: scarcity can be alleviated through reduction of waste. It is well-known that in all economic activities there is waste. For example, regarding the global food provision, it is estimated that a third of all food produced is lost or wasted (Gustavson et al., 2011). Thus, arguably, economics should either theoretically embrace waste reduction, when economising is discussed, or robustly reject this idea. However, the popular textbooks by McEachern (2017), Parkin (2015) as well as Mankiw and Taylor (2017) do not discuss or mention Lean or waste reduction at all.
Why this failure to explain or silence regarding Lean? There is no common conceptual ground between Lean and established managerial disciplines, such as organisational behaviour and economics, as a theoretical explanation of Lean is missing. A theory of Lean is badly needed for other related disciplines to understand Lean, to ensure a complete coverage of the phenomena they address.
1.4 If we are looking for the theory of Lean, what are we after?
The concept of theory implies as such a certain structure to a theory. According to the well-known account by Whetten (1989), a theory consists of four parts, responding to questions on (1) What, (2) How, (3) Why and (4) When, Where, Who. Regarding the What question, a theory will be based on concepts, factors or variables that refer to its subject. For responding to the How question, the theory will include relationships or principles presented through the selected concepts, factors or variables. The Why question is about the conceptual assumptions underpinning the theory. Finally, the questions When, Where, Who are responded by specifying the contextual assumptions of the theory: in which conditions is the theory valid.
Now, it is possible to outline what we are after when looking for a theory of Lean. Regarding the What question: Theory of Lean is a theory of production (or operations) management. Thus, a conceptualisation of production is needed, along with associated concepts. This focus also determines the major ends to be covered: to get something produced, for minimal costs and for maximal value to the customer (Koskela, 2000).
Regarding the How question: Theory of Lean is a managerial theory. According to Argyris (1996), the task of a theory of management is to produce generalisations that are actionable by managers in everyday life. Further, according to Argyris, managerial theories purport to define activities through which intended consequences can be achieved; thus, the possible means to the ends mentioned above.
Regarding the Why question: There are at least two consequential questions needing to be responded. In producing, we have to interact with the world, and thus we need to have a view on what is there in the world. And we need information and knowledge for producing: where does it come from? These are philosophical questions, the former question falling into ontology (or metaphysics), and the latter into epistemology. Note that the assumptions subscribed regarding these questions are actionable, in the sense of influencing actions. However, customarily, philosophical questions are not discussed in production management, and thus ontological and epistemological assumptions are extremely rarely discussed explicitly.
Lastly, regarding the questions When, Where, Who: The relevant responses concern the empirical conditions where the discussed theory is valid. Although this sounds straightforward, these conditions are often given incompletely or vaguely, if at all.
In practice, it is usually seen that responses to the What and How questions are enough to characterise a theory; this convention is followed here. In turn, the mentioned responses to the Why question occur as general orientations in thinking, and therefore they are covered separately in the following. The When, Where and Who questions, although important, will not be covered.
1.5 What is the mainstream theory of production management?
To fully understand and appreciate the theory and philosophy of Lean, it is necessary to compare it to the old counterpart.
1.5.1 Theory of production
The concept of transformation (Starr, 1989; Holweg et al., 2018) has provided the mainstream theory of production management. It refers to the transformation of inputs into outputs (Starr, 1989). From a practical viewpoint, the related procedure called decomposition provides the power of this theory, although it is rarely explicitly presented. In decomposition, the total productive task is successively broken down into smaller tasks, until they can be assigned to operatives or companies in the supply chain. Decomposition is based on two related assumptions. First, that the tasks emerging from decomposition are by their nature similar input–output transformation as the original total task. Second, that the decomposed tasks are mutually independent. These assumptions make managing easy: all the attention can be turned into optimally executing the decomposed tasks, as in this way the total optimum is (assumed to be) reached.
However, these assumptions are an idealisation: of course, tasks are usually dependent on other tasks. F...