Design Process Stability: Observations of Batch Size, Throughput Time and Reliability in Design

Despite recent developments in construction design management, too much variability still occurs in design processes. Batch size (BS) and throughput time (TT) reduction are recurring concepts in the lean construction literature related to the Last Planner© System (LPS). These three parameters are often used to reduce variability and improve flow and reliability in work processes. Some have attempted to reduce design variability through lean design management (LDM) and agile methods, but very few studies have analysed the interaction of these parameters in the design process. The purpose of this study is to investigate these variables and their interactions. Design process stability and reliability were measured over nearly two years in this study by using three parameters. According to the results, design teams with smaller BS’s of design tasks and higher percentages of planned tasks completed also had shorter design task TT’s. Designers may use these findings to improve their workflow monitoring and as a novel addition to LDM and coordination metrics.