A Lean Workflow Index for Construction Projects

Traditional monitoring methods for construction project control based on the earned-value method provide measures of cash flow and schedule compliance. However, they do not tell managers anything about the quality (stability, continuity) of the workflow, and the results are not timely enough for effective control. In order to improve workflows where lean production control is applied, direct measures of workflow are needed. Kalsaas and others have proposed measures of daily or weekly workflow for specific tasks, but their measures cannot be used for real-time project control and they were not tested or calibrated over complete project life-spans. The Lean Workflow Index (LWI) that we propose directly reflects the smoothness and continuity of workflow lines in flowline charts. In the first stage we define a set of possible tracking parameters and propose the lean workflow index formula as a combination of them. A survey of lean experts was conducted in which they graded workflow quality for as-built flowline records for 12 projects. The results of the survey were then used to calibrate parameter coefficient values in the LWI formula by using a goal seeking algorithm. The resulting formula was used to compute the LWI for three high-rise residential projects. The major advantage of the proposed lean workflow index is that it monitors project workflows in real-time so that construction teams can be continuously aware of and improve their performance in the areas that are measured.