Design and construction changes often cause rework, increase a project’s cost, and delay its delivery. Data was obtained from a mechanical contractor in order to study rework timing and how it disrupts their detailing, fabrication, and installation processes. A set of simulation models illustrate the impact of rework timing. The focus is on early changes, that is, changes that become known when the contractor is detailing, so they can be dealt with either (1) right away during detailing, (2) during fabrication, or (3) during on-site installation. One model shows that dealing with changes in the detailing phase not only affects that phase but can have negative impacts on installation as well. Another model shows that detailing a project to a set of approved drawings and maintaining those until project completion, forces changes to be pushed downstream to site installation, which makes the impact of those changes more transparent to all players involved and can reduce negative iteration. The question addressed in this paper is: When early changes occur, is there benefit to incorporating them during site installation instead of trying to capture, re-detail, and change drawings? Practitioners can use this research to assess resources to avoid rework.
changes, contracts, detailing, discrete event simulation, lean construction, mechanical contractor, rework
Feng, P.P. , Tommelein, I.D. & Booth, L. 2008, 'Modeling the Effect of Rework Timing: Case Study of a Mechanical Contractor' In:, Tzortzopoulos, P. & Kagioglou, M., 16th Annual Conference of the International Group for Lean Construction. Manchester, UK, 16-18 Jul 2008. pp 691-702