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This article is presented by:
TAN WEE LENG

The Application of Lean Construction to Reduce
Wastes in Construction Process Flow

ABSTRCT
There are a lot of non-value adding activities or wastes in construction practices and many among those were left unnoticed or unattended. Previous studies have shown that there were significant amounts of values loss due to construction process flow wastes and tremendous productivity improvements can be achieved by simply targeting at reducing or eliminating those wastes and/ or improve the process flow. This thesis was conducted on the basis to study the waste concepts and the level of “leanness” in local construction practices based on philosophies and principles drawn by Lean Construction. A quantitative survey was carried out through structured questionnaires over a randomly selected group of managerial personnel in construction activities. The results from the study show that the respondents have a relatively low recognition over contributory time wastes group compared to direct conversion wastes group and non-contributory time wastes group as categorised in the study. The correlation analyses also show almost no significant inter-relationships between wastes recognition and wastes controlled, wastes recognition and wastes occurrence frequencies, and wastes controlled and wastes occurrence frequencies for those 3 waste categories (except 1 negative significant case are recorded on waste recognition vs. waste controlled for contributory time wastes). This has suggested that a very high level of subjectivity possessed by the respondents on recognising, controlling and witnessing the actual occurrence of construction wastes where majority cases are recorded with nonconsistent pairs relationships. In this study, a cluster of waste cause variables have also been examined against their likelihood to impact on the construction processes as well as relating those variables directly to specific construction wastes. This will serve as a good exercise to expose the root sources to particular construction wastes. In conclusion, the outcomes of the research suggested that there still have rooms for construction process improvements with the application of lean construction and proper waste concepts instilled to all level of construction personnel and processes.

INTRODUCTION
1.1 Research background
Construction is a key sector of the national economy for countries all around the world, as traditionally it took up a big portion in nation’s total employment and its significant contribution to a nation’s revenue as a whole. However, until today, construction industries are still facing numbers of contingent problems that were bounded to be resolved since the past time. The chronic problems of construction are well known such as Low productivity, poor safety, inferior working conditions, and insufficient quality. (Koskela, 1993) and the phenomenon of the poor performance and conditions in construction had long been witnessed and recorded by academics and practitioners throughout the world regardless in developed countries e.g. England (Eaton, 1994) or in developing countries e.g. Chile. (Serpell et al., 1995) Nowadays, increasing foreign competition, the scarcity of skilled labour and the need to improve construction quality are the key challenges faced by the construction industry. Responding to those challenges imposes an urgent demand to raise productivity, quality and to incorporate new technologies to the industry. A lack of responsiveness can hold back growth, and to development of the needed infrastructure for the construction industry and other key activities in the country. (Alarcón, 1994) Pertaining to the challenges faced by the construction industry, numerous researches and studies had been carried out for the past decades to identify the causes to the construction problems and some of them had went on to suggest and recommend solutions to rectify those identified problems. The early phase of these studies mainly focused on the “end” side of the construction process with the introduction of new technologies and equipment to speed up the construction process and improve overall productivity. It was only until late 1980s where a new construction improvement movement was being initiated by looking into the “mean” side of the construction process-related problems in a more holistic and structured way based on the philosophy and ideology of lean production. With the lean construction paradigm, construction industry had started to be reviewed and evaluated in the possibilities of implementing these new lean perspectives of production concepts in the construction processes to optimise the overall construction performance on construction stage as well as design stage. However, in construction, there has been rather little interest in this new production philosophy. (Alarcón, 1994) This matter laid on whether or not the new production philosophy has implications for construction and will give any significant impacts on the productivity improvement. According to the scholars and researchers in Lean Construction, the new construction production philosophy is laid on the concepts of conversion and flow process. Therefore, performance improvement opportunities in construction can then be addressed by adopting waste identification/ reduction strategies in the flow processes in parallel with value adding strategies with the introduction of new management tools and
with proper trainings and education programs. Unfortunately, these new lean
construction concepts especially those on wastes and values most of the times are not
well understood by construction personnel. Particularly, waste is generally associated
with waste of materials in the construction processes while non-value adding activities
such as inspection, delays, transportation of materials and others are not recognised as
waste. (Alarcón, 1995) As the result of that, the productivity of construction industry
cannot be fully optimised due to the narrow interpretation on the concept of waste
current adopted. In this case, substantial education programs need to be arranged for all
related parties involved in order to implement the new process improvement strategies
successfully throughout the construction process cycle.