What a Waste of Time

Abstract

The elimination of waste is a core focus of lean construction. Reducing waste will increase work efficiency. For several years it has been debated how flow and the efficiency of processes can be measured. Kalsaas, Koskela, and others conclude that in order to operationalize workflow measures, it must be disconnected from productivity and throughput measures and instead focus on work efficiency. However, an extensive and valid baseline of work time efficiency is missing in the community. The establishment of such becomes the objective of this research.The method is an extensive litterateur review that identified 474 case studies of time waste measures from the 1970s until today. This sample is analyzed in different ways, among others showing that the average direct work time is 43.6%.The results show that the sample contains considerable uncertainty, which is mainly due to an inconsistent understanding of direct work, indirect work, and waste work in the many different studies. Besides, the results show no statistically significant difference between the performance of varying trades or between countries.The construction industry can use this research as a baseline for the current direct work level and apply this as a benchmark in a continuous improvement process.

Robustness of Work Sampling for Measuring Time Waste

“…', and 'how does implementing Last Planner and other Lean approaches reduce time waste?' are addressed in several research studies, e.g., (Bølviken & Kalsaas, 2011;Kalsaas et al, 2014;Wandahl et al, 2021). Bølviken & Kalsaas (2011) recognized a need for a more valid method for measuring time waste.…”

“…However, recent studies conclude that DW is statistically significantly correlated to construction labor productivity at activity, project, and national levels (Araujo et al, 2020;Siriwardana et al, 2017) and, thus, can be applied as an acceptable indicator for productivity. Wandahl et al (2021) identified 474 case studies where WS was applied in construction. Thus, it can be concluded that the method is widely used.…”

“…Categorizing work activities into direct work and subcategories of preparatory and waste work is very inconsistent (Josephson & Björkman, 2013;Wandahl et al, 2021). This makes cross-case comparison difficult, like any longitudinal meta-analysis (Horman & Kenley, 2005;Josephson & Björkman, 2013).…”

Assembly Process in Off-Site Construction: Self-Lock Device as a Key to a Lean Approach

“…drywall installing, finish, priming and painting) it seems reasonable to believe it would take at least half the time to simply pursue the on-going task in-factory than to prepare tools and materials on-site and complete the task. Although it appears to be an optimistic ratio, the findings of Wandahl et al (2021) state that on-site labor is being used at only 43% for direct work. Moreover, the rates of on-site workers is estimated to $65/h compared to $32/h for off-site workers in Province of Quebec (CEO of engineering group, 2022).…”

Location-Based Work Sampling

“…Over the years, the technique has been employed by Lean practitioners and researchers for several different purposes: (a) to provide insight for comparing the average productive workforce utilization to respective work processes in various projects (Picard, 2002); (b) to measure labor efficiency and inefficiency (Neve et al, 2021;Ramaswamy, 2009); (c) to measure and conceptualize flow and workflow (Kalsaas, 2011;Wernicke et al, 2017); (d) to identify the share of time spent on a single activity of the same construction process on different job sites, e.g., transportation (Pérez et al, 2015); (e) to set up a baseline measure for improvement and to serve as a challenge to management and the workers (Neve & Wandahl, 2018); (f) to understand the evolution of share of time spent in different work categories along the years (Wandahl et al, 2021), among others.…”