Little work has been done to date in formally modeling concepts of lean construction, such as uncertainty, waste, flow, conversion, and push vs. pull techniques. This lack of formalization has been blamed in part on the inability of the project-management tools commonly used in industry to describe the construction process and its salient features at a level at which lean production can be studied. However, existing process-level construction models prove to be useful in this regard. Accordingly, this paper describes the use of computer software for discrete-event simulation to represent various construction process characteristics relevant to lean production. Two examples are provided. The first one illustrates the flow and conversion of pipe spools through their design and installation process. Spools exemplify unique materials, measured in discrete quantities. The second one illustrates the flow and conversion of concrete through its batching and placement process. Concrete exemplifies bulk materials, measured by volume. The examples show what types of system-level information can be generated using discrete-event simulation and how this information may be used to redesign construction processes in order to make them leaner.
lean construction; materials management; discrete-event simulation; uncertainty; process planning; concrete placement