in Construction Operations
Seung Heon Han, M.ASCE1; Myung Jin Chae, Ph.D., P.E.2; Keon Soon Im, P.E.3; and Ho Dong Ryu4 Abstract: Many researchers and project managers have attempted to improve project performance by applying new philosophies such as lean principle, just-in-time, pull scheduling, and last planner. However, very little research has been conducted on setting deﬁnite quantitative goals for performance improvement while considering the defect rate involved in the construction operations. This research explores practical solutions for construction performance improvement by applying the six sigma principle. This principle provides the metrics required to establish performance improvement goals and a methodology for measuring and evaluating improvement. The proposed approach is expected to achieve more reliable workﬂows by reducing process variability to ﬁt in a desirable range—thereby improving the overall performance through the evaluation of the quality level in current construction operations. To verify the suggested methodology, two case studies have been presented and process simulation analyses are performed to observe the performance changes based on the six sigma principle. Critical total quality control, as the sigma level rises, is also discussed. DOI: 10.1061/ ASCE 0742-597X 2008 24:1 21
CE Database subject headings: Quality control; Simulation; Productivity; Construction management.
In the pursuit of productivity improvement, it is important to ensure the quality of work processes to enhance the overall reliability and stability of construction operations. There have been a number of construction productivity improvement principles such as lean production, just-in-time JIT , rapid machinery
changeovers, pull scheduling, last planner, etc. Thomas et al. 2003 . Despite the successful applications, however, most of the results fell short of our expectations of a quantitative and practical method or metrics for assessing the defect rates of construction operations.
The defect rate in construction processes is largely caused by unreliable workﬂow when sources of process variability are involved Tommelein 2000; Hopp and Spearman 2000; Howell et al. 2001; Thomas et al. 2002 . The lean principle attempts to address the effect of variability, but not to eliminate or reduce variability by removing the root causes of the whole Abdelhamid 2003 . In order to estimate the defect rates involved in construction operations in a more quantitative and organized way, this research applies the six sigma principle. The six sigma principle 1
Associate Professor, Dept. of Civil & Environmental Engineering, Yonsei Univ., Seoul 120-749, Korea corresponding author . E-mail: firstname.lastname@example.org
Senior Researcher, Korean Institute of Construction Technology, Seoul, Korea. E-mail: email@example.com
Manager, Daelim Industrial Construction Company, Seoul, Korea. E-mail: firstname.lastname@example.org
Engineer, Hyundai Engineering and Construction Co., Seoul, Korea. E-mail: email@example.com
Note. Discussion open until June 1, 2008. Separate discussions must be submitted for individual papers. To extend the closing date by one month, a written request must be ﬁled with the ASCE Managing Editor. The manuscript for this paper was submitted for review and possible publication on November 27, 2006; approved on May 11, 2007. This paper is part of the Journal of Management in Engineering, Vol. 24, No. 1, January 1, 2008. ©ASCE, ISSN 0742-597X/2008/1-21–31/$25.00.
has been an effective statistical-based methodology in measuring the defect rate in an attempt to maintain a high-standard quality level, particularly in construction materials. This study focuses on the development of the general methodology to apply the six
sigma principles on construction operations rather than construction materials in terms of the barometers to measure, evaluate, and improve...