A lean construction framework with Six Sigma rating
Authors: Al‐Aomar Raid 
Published: November 2012

PurposeThe purpose of this paper is to investigate the application of lean construction practices in the construction industry and develop a practical and applicable framework that incorporates Six Sigma rating into the best practices of lean construction. The objective is to help the industry reduce waste and cost, increase effectiveness, and improve quality.Design/methodology/approachA generic yet practical framework of lean construction is developed using the guidelines of project lean delivery system developed by the Lean Construction Institute (LCI). Applicable lean techniques and Six Sigma rating are integrated into the developed framework. A cyclical look‐ahead planning and execution approach is used to implement the lean construction techniques. A set of Lean Six Sigma (LSS) performance indicators is defined to measure performance, set target threshold values, and guide improvement actions. A case study of the construction industry in Abu Dhabi (AD) is used to clarify the proposed approach and identify its key practical aspects.FindingsAnalysis of wastes in AD construction industry reveals 27 types of construction wastes. These wastes were categorized into the seven types of wastes. Defects (errors and corrections) are found to be the most common type of construction waste in the surveyed companies. This calls for integrating Six Sigma rating into the proposed lean construction framework. The other common types of wastes are overprocessing and delays. Lean project management is focused on assessing a set of key performance indictors (KPIs) at the end of each “look‐ahead” period. First lean practices are employed during the period and Sigma Rating is assessed at the end of the period along with other KPIs. The proposed LSS‐KPIs were able to measure progress and guide improvement.Research limitations/implicationsThe credibility of the research findings is dependent on the accuracy and reliability of collected data from construction companies. Implementing lean construction techniques within a look‐ahead period is not expected to achieve significant project gains in terms of quality, speed, and cost without adopting the overall lean construction framework.Social implicationsThe work of construction companies largely contributes to the quality and safety of public and society at large through residential and commercial buildings, transportation, and infrastructure projects. Lean construction practices and Six Sigma rating positively impact these important aspects and often result in reducing waste and costs, improving safety, and saving energy resources in construction projects.Originality/valueResearch significance stems from the focus on increasing the effectiveness of the construction industry. Research contributions include the development of an applicable lean construction framework that integrates lean construction practices with Six Sigma rating. This contributes to the effort of applying Lean Six Sigma (LSS) in the vital field of construction. This research prescribes a systematic approach for implementing the proposed framework within a cyclical look‐ahead period and highlights the practical implications of the proposed approach. Also, the research provides an effective periodic measurement system of project effectiveness based on five LSS key performance indices.