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What is Lean Construction - 1999

WHAT IS LEAN CONSTRUCTION - 1999
Gregory A. Howell1 ABSTRACT The origins of lean production are reviewed and a claim made that it is a new form of production management, that is neither mass nor craft. Then the applicability of lean production in construction is considered and nature of lean construction discussed in comparison with current practice. KEY WORDSLean construction, lean production, production management

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P.E., Director, Lean Construction Institute, Box 1003, Ketchum, ID 83340, 208/7269989, fax: 208/726-0699, ghowell@micron.net

Proceedings IGLC-7

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Howell

INTRODUCTION Lean construction much like current practice has the goal of better meeting customer needs while using less of everything. But unlike current practice,lean construction rests on production management principles, the “physics1” of construction. The result is a new project delivery system that can be applied to any kind of construction but is particularly suited for complex, uncertain, and quick projects. HISTORY OF LEAN PRODUCTION Lean production was developed by Toyota led by Engineer Ohno. He was a smart if difficult person dedicated toeliminating waste. The term “lean” was coined by the research team working on international auto production to reflect both the waste reduction nature of the Toyota production system and to contrast it with craft and mass forms of production (Womack et al. 1991). Engineer Ohno shifted attention to the entire production system from the narrow focus of craft production on worker productivity and massproduction on machine. Ohno followed the work of Henry Ford and continued the development of flow based production management. But unlike Ford who had an almost unlimited demand for a standard product, Ohno wanted to build cars to customer order. Starting from efforts to reduce machine set up time and influenced by TQM, he developed a simple set of objectives for the design of the production system:Produce a car to the requirements of a specific customer, deliver it instantly, and maintain no inventories or intermediate stores. Waste is defined by the performance criteria for the production system. Failure to meet the unique requirements of a client is waste, as is time beyond instant and inventory standing idle. A morning cup of coffee serves as an example. Instant delivery is possible but wemust either have an intermediate inventory, coffee in the pot, or accept a cup of “instant” which hardly meets requirements of someone craving a low-fat double latte. Moving toward zero waste, perfection, shifts the improvement focus from the activity to the delivery system. Engineer Ohno and other Japanese engineers were familiar with mass production of cars from their plant visits in the UnitedStates. Where US managers saw efficiency, Ohno saw waste at every turn. He understood that the pressure to keep each machine running at maximum production led to extensive intermediate inventories he called “the waste of over production.” And he saw defects built into cars because of the pressure to keep the assembly line moving. Production at all costs meant defects were left in cars as theypassed down the line. These defects disrupted down stream work and left completed cars riddled with embedded defects. Where the US approach aimed to keep the machines running and the line moving to minimize the cost of each part and car, Ohno’ system design criteria s set a multi-dimensioned standard of perfection that prevented sub-optimization and promoted continuous improvement. Zero time deliveryof a car meeting customer requirements, with nothing in inventory required tight coordination between the progress of each car down the line and the arrival of
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The idea of a “physics” of production is borrowed from “Factory Physics”, an excellent text on production management (Hopp and Spearman 1996).

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26-28 July 1999, University of California, Berkeley, CA, USA

What is Lean...