Measuring Waste and Workflow in Construction

Bo Terje Kalsaas1

1Professor, Dr.Ing., Department of working life and innovation, University of Agder, 4846 Grimstad, Norway, Phone +47 97082582, e-mail: bo.t.kalsaas@uia.no

Abstract

Applied to continuous improvement work in a construction site setting, a way to operationalize workflow measurement in the construction industry is proposed in this paper. Our conceptualisation uses the metaphor of a river. This river flows with a certain smoothness, intensity and quality (more or less turbulently). The water represents the man-hours available to the employer – which are divided between productive work (direct work, indirect work, planning and HSE work); and waste (e.g. rework, waiting and other forms of downtime). We distinguish between observable and hidden waste. Hidden waste is tied to the potential improvement of methods used in transformation work and indirect work. Our conceptualisation draws on the OEE (Original Equipment Efficiency) concept from manufacturing. For practical reasons, work intensity is assumed constant. Thus the work pressure is even, but the tasks are not necessarily productive. Observable waste, except rework, relates to the smoothness of the river; rework relates to its quality. Flow was measured through observations and self-reporting. All workmen involved in a construction project over time, e.g. for one week, fill in a form estimating their time use, including the daily time loss and its causes. The principle is to detect “making-do” and other sources of waste or downtime. Suspecting that a time ratio cannot produce enthusiasm whereas time reduction can, low values for wasted time are to be interpreted as good flow. Sufficient data validity depends on staff training and motivation. A period of measurement culminates in a joint meeting with the workmen. This is where continuous improvement comes in. Results are discussed, efficiency improvement measures identified, and action plans prepared. Later, e.g. another two months into the project period, new measurements are made, and the figures are followed up with reflections about further improvements.

Keywords

Workflow, waste, measurement, continuous improvement

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Reference

Kalsaas, B.T. 2013, 'Measuring Waste and Workflow in Construction' In:, Formoso, C.T. & Tzortzopoulos, P., 21th Annual Conference of the International Group for Lean Construction. Fortaleza, Brazil, 31-2 Aug 2013. pp 33-42

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