More Just-in-Time: Location of Buffers in Structural Steel Supply and Construction Processes
Iris D. Tommelein1 & Markus Weissenberger2
1Associate Professor, Constr. Engrg. and Mgmt. Program, Civil and Envir. Engrg. Department, 215-A McLaughlin Hall, Univ. of California, Berkeley, CA 94720-1712 and Research Associate, Lean Construction Institute, phone: 510/643-8678, fax: 510/643- 8919, [email protected]2Exchange student in the Constr. Engrg. and Mgmt. Program at U.C. Berkeley in 1997-98, now Senior (5-year Civil Engineering Degree), Technical Univ. Hamburg-Harburg, Germany, [email protected]
Abstract
The erection of a building’s structural steel frame is a major construction phase on many a project. The main resource in this process, the steel erector’s crane, defines not only the pace of erection of steel, but also the pace for handling and installing many other structural and non-structural materials. This production system cannot afford any delays. Some claim that structural steel therefore is managed as a just-in-time (JIT) process with materials being delivered to site as needed and installed promptly. This is the case only in appearance as is clear when one considers the JIT principles that were developed as part of Toyota’s lean production philosophy. To illustrate the point, this paper draws on examples of typical structural steel supply chains from the industrial- and building construction sector. The use of symbols from manufacturing is investigated to map key production steps as well as buffers in-between them in order to elucidate where resources do and do not flow. Industry practices in these two construction sectors vary significantly. Neither one is lean. This paper reports on a preliminary investigation into the location of buffers in the structural steel supply and construction process. The reasons for having buffers at various locations are explored. A more in-depth investigation is recommended to gain a deeper understanding of the buffer sizing criteria and steel component sequencing rules that govern current practices. Insight into these will then help determine which buffers can be trimmed in order to reduce work in progress and cycle time. This will support the effort of achieving “more JIT” by making processes within individual companies as well as across the entire steel supply chain leaner.
Keywords
Supply-chain mapping, integration, structural steel, fabrication, erection, pull-driven scheduling, just in time, JIT, kanban, buffer, lean construction.
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Reference
Tommelein, I. D. & Weissenberger, M. 1999. More Just-in-Time: Location of Buffers in Structural Steel Supply and Construction Processes, 7th Annual Conference of the International Group for Lean Construction , 109-120. doi.org/
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