Production Rate - Construction Quality Relationships in Us Residential Construction

Kenneth D. Walsh1, Howard H. Bashfordz2 & Anil Sawhneys3

1AGC—Paul S. Roel Chair in Construction Engineering and Management, Department of Civil and Environmental Engineering, San Diego State University, San Diego, CA 92l82—l324, TEL:6l9/594·09l l, FAX: 619/594-8078, kwalsh@mail.sdsu.edu
2Associate Professor, Del E. Webb School of Construction, Arizona State University, Tempe, AZ, 85287- 0204, TEL: 480/965-4513, FAX: 480/965-1769, h0wa1‘d.bashford@asu.edu
3Associate Professor, Del E. Webb School of Construction, Arizona State University, Tempe, AZ, 85287- 0204, TEL: 480/965-7417, FAX: 480/965—l769, anil,sawh11ey@asu.edu

Abstract

Little’s Law describes the relationship between throughput, cycle time, and work-in-progress (WIP) for a process. This relationship has been shown to apply over a long time horizon in production or "high-volume" residential construction, wherein specialized trade contractors perform related sequences of work in a tightly connected production system. This finding suggests new approaches might be needed in construction management, and that other relationships from production mechanics could apply to construction operations. The dramatic and rapid workload variability in residential construction makes direct application of Little’s Law in real-time problematic, but more importantly fosters flexible crewing that confounds definition of utilization. Trade contractors employ very few crews directly, and have wide networks of additional crews they can bring on line, with ever less knowledge of their ability and quality of production. As a consequence, one might hypothesize that work- in-progress and/or throughput would exhibit a relationship to construction quality. Residential building permit and inspection data from a major residential market were analyzed to confirm the existence of such a relationship. This analysis reveals a larger question about the reasons for code compliance inspection failure and their implications for identifying production system waste.

Keywords

Residential constmction, Production mechanics, Variability, Code Compliance Inspections

Files

Reference

Walsh, K.D. , Bashfordz, H.H. & Sawhneys, A. 2004, 'Production Rate - Construction Quality Relationships in Us Residential Construction' In:, Bertelsen, S. & Formoso, C.T., 12th Annual Conference of the International Group for Lean Construction. Helsingør, Denmark, 3-5 Aug 2004.

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