Comparing Process Improvement Initiatives Based on Percent Plan Complete and Labour Utilization Factors

Vijay R. Chitla1 & Tariq S. Abdelhamid2

1Graduate Student Research Assistant, 9 Farrall Hall, Construction Management Program, Michigan State University, East Lansing, MI 48824-1323. Email: chitlavi@msu.edu
2Assistant Professor, 207 Farrall Hall, Construction Management Program, Michigan State University, East Lansing, MI 48824-1323. Email: tabdelha@msu.edu

Abstract

The Last Planner System® is a process-based system developed to enable production planning and control under a lean construction paradigm. The Percent Plan Complete (PPC) is a metric that reflects the effectiveness of production planning and the reliability of workflow from one trade to another. Process improvement initiatives are identified when 100% PPC is not achieved. In contrast to this system, conventional construction management derives its production process improvement initiatives from productivity improvement studies that use metrics of non-utilization such as non-productive time or Labor Utilization Factors (LUF) as the metric of superior production performance. This paper investigates the differences, if any, in process improvement initiatives predicated on PPC compared to those predicated on LUFs. This was accomplished by conducting a study in a Manufactured Housing plant where workers’ utilization at 10 production stations were measured using productivity ratings while also measuring PPC at the same stations. The average LUF for the 10 stations was 52% and the average PPC for the same was 78%. Attempts to improve PPC through constraint analysis techniques revealed more fundamental problems than those revealed by trying to improve LUF. In addition, the PPC metric exposed the ‘hidden-factory’ despite that the production goals were being met. The study confirms that PPC is a global measure of production system planning efficiency while LUF is a measure of local production activation. A linear regression analysis was also performed revealing that PPC and LUF are not strongly correlated (r = 0.4, p-value = 0.3) in non-lean production systems. Thus, the only viable way to increase workflow reliability in production systems is to increase PPC. KEY WORDS

Keywords

Lean construction, Manufactured Housing, Percent Plan Complete (PPC), Labor Utilization Factors (LUF)

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Reference

Chitla, V.R. & Abdelhamid, T.S. 2003, 'Comparing Process Improvement Initiatives Based on Percent Plan Complete and Labour Utilization Factors' In:, 11th Annual Conference of the International Group for Lean Construction. Virginia, USA, 1-.

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