Waste Problems in Vietnam Construction Industry Based on Lean Philosophy

Abstract

Waste has been considered as a great source of value losses of construction projects under the viewpoint of stakeholders. Nowadays, waste is defined as not only related to materials, but also related to time for non-contributory and contributory activities such as waiting, inspection, idle, transport, etc. Thus, there are many causes derived from the reality for waste occurrence. Among them, poor production planning and control has been defined as the most frequent cause. This research aims to examine the waste problems in Vietnam construction industry based on the philosophies of lean production. Previous studies have shown that Lean Construction (LC) proposes an approach to design production processes to reduce wastes in order to create the maximum amount of value. There are six objectives that have been formulated to conduct this study including: (1) examine general perception of the local construction professionals with the new waste concepts in LC; (2) identify main waste factors and their cause in current construction performance; (3) investigate the latent relationships between waste factors; (4) determine the "Waste Occurrence Level Indicators" (WOLI) for the construction industry, (5) develop a model to predict the impact of wastes on project performance cost; and (6) analyze the main waste factors that have strong impact on project cost. In addition, a comparison with some selected countries was then made to gain the comprehensive view about waste problems. As mentioned early, the foundation of this study was based on principles and philosophies of lean production. The population of the survey are the professionals who have experience in construction project management in Ho Chi Minh City, Vietnam. Due to the certain limitations, the non-probability sampling has been applied in this study. The method used for collecting data was questionnaire survey according to the opinions from several experts. All uncompleted feedbacks from respondents were deleted to increase the reliability of data. The tools used for data analysis included both descriptive and inferential statistical analysis. The main results of analysis have shown that the professionals in construction industry highly perceived the new concepts of waste. However, these wastes were not controlled well by them in the practice. Moreover, there was no interrelationship between recognition, control, and frequency of wastes. According to the ranking of frequency, the main waste factors were identified, as well as the main causes. Through the cause-and-effect analysis, people-related cause group was found as the most influent group for all wastes. Based on factor analysis, there were five components extracted from nineteen initial waste factors with 56.7% of explained variance. Based on these five components, the "Waste Occurrence Level Indicator" (WOLI) was defined as 61.55 in the scale of 100. It indicates that level of waste in the construction industry is quite high. Furthermore, based on the respondents' experience, the average project cost loss due to wastes was identified as up to 9.36% of total cost. Two models have been developed to predict the effect of wastes on project performance cost, i.e., Artificial Neural Network (ANN) model and Linear Regression (LR) model. The results showed that ANN model (MAPE = 1.35%, and R2 = 91.1%) produces the higher degree of accuracy compared to the LR model (R2 = 79.8%). The main waste factors that have strong impact on the project performance cost were then determined by elasticity test. The main contribution of this study is the examination on the status of wastes that are related to time used to complete a project because the traditional viewpoint only focused on wastes related to resource.