Lean principles in the construction industry

The construction sector is one of the main pillars of economic growth and country development for all nations across the globe, and a link in the chain of dependencies between all industries in terms of consuming inputs and providing products. Nonetheless, it is estimated that 50\% or more of the required resources and effort as to deliver the built environment consists in waste, or non-added value effort. The same lack of effectiveness of the labor hour in the past 50 years has caused for the construction industry to fall behind in the terms of major advancements. Over time, the workforce landscape has also changed due to demographic and labor shifts, reducing the labor availability and consequently increasing the relative cost of a built environment.

Lean construction is a robust approach that attempts to reduce waste in the construction projects, enhance performance and cut down cost for the industry and the society on a larger scale. \cite{LeanConstructionAnEffectiveApproach} The concept first emerged in the 80's after gaining full acceptance in the West due to the major improvements displayed in the manufacturing operations and has its roots in Toyota's production management principles.

This article aims to answer the following research questions:

• What are the current waste sources involved in the construction projects?
• How can the Lean principles be tailored for this sector and counter them?
• What limitations need to be considered before seeking to include elements of this methodology in the planning phase?

Its structure will take the reader through a brief history of the concept by presenting the Toyota story, the takes from it and the key differences between manufacturing and construction projects, the five traditional core principles of the Lean management and the waste sources in the targeted projects, implementation directions and limitations.

Big idea

History

The concept of Lean stems from Toyota's Lean production, also known as Toyota Production System (TPS), which fundamentally applied precast construction principles to their manufacturing processes with the end goal of creating a leaner organization.

The core concepts of TPS and their intercorrelation can be visualized in a structured manner through the TPS house, consisting of two pillars supporting a roof and a foundation. A good understanding of this is essential for developing and improving a lean system which will subsequently aid the company in removing waste and non-value adding effort, resulting in increased efficiency and maintenance of superior value and quality. \cite{FromLeanProductionToLeanConstruction}

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As it can be observed, the procedure puts much emphasizes on the supply chain's speed. The underlining trend is to shorten the lead time by reducing or completely eliminating waste at each step in the process to produce the best quality, at a low cost, delivered on-time, while also enhancing safety and morale, principles known as QCDSM.

Nonetheless, a successful implementation of TPS requires more than adopting and applying a set of tools, methods and techniques. It demands a pervasive and intensive cultural transformation at a company level and the development of a strong collaborative relationship with the suppliers, which will lead to quality materials being delivered consistently and productively.