A Study of the Relationship Between Buffers and Performance in Construction

Masanobu Sakamoto1, Michael J. Horman2 & H. Randolph Thomas3

1Graduate Student, Depart. Civil & Envir. Engrg., Penn. State Univ., 104 Transportation Research Building, University Park, PA 16802, 814-863-1910 FAX 814-865-3039, mus107@engr.psu.edu
2Assistant Professor, Depart. Archi. Engrg., Penn. State Univ., 211 Engrg. Unit A, University Park, PA 16802, 814-863-2080 FAX 814-865-4789, mjhorman@engr.psu.edu
3Professor, Depart. Civil & Envir. Engrg., Penn. State Univ., 203 Transportation Research Building, University Park, PA 16802, 814-863-1901 FAX 814-865-3039, hrt1@engr.psu.edu

Abstract

Lean proponents argue that we should eliminate buffers because they are wasteful, impede workflow, and hinder performance. Yet, there is some work in (lean) construction that calls this into question. Buffers have been commonly used to shield production by absorbing the impact of uncertainties and variability that would normally disrupt production. Buffers can take many forms including materials (inventory), W.I.P. (work-in-procress, subassemblies, stock, safety stock), deliberate and unintentional delays (time buffers, lags, pacing mechanisms), and excesses of labor and equipment capacity (capacity buffers). To lean producers, these items slow production, obscure and worsen quality problems, and burden management with unnecessary activity. However, in construction, where conditions are often uncertain and variable, lean constructors have suggested that buffers be sized and located according to the conditions. This paper analyzes the relationship between buffers and performance in construction with data collected from three commercial projects to see how buffers influence performance. The size of the buffer between rebar fabrication and installation in the construction of a structural system is compared to the labor performance of the crew. The results show that some buffer is needed between steps in order to achieve best performance in the construction operations studied.

Keywords

Buffers, lean construction.

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Reference

Sakamoto, M. , Horman, M.J. & Thomas, H.R. 2002, 'A Study of the Relationship Between Buffers and Performance in Construction' In:, Formoso, C.T. & Ballard, G., 10th Annual Conference of the International Group for Lean Construction. Gramado, Brazil, 6-8 Aug 2002.

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