On the basis of the existing literature, waste in the context of construction can be classified into eight types, namely defects, overproduction, waiting, not-utilizing talent, transportation, inventory excess, motion waste, and excess processing.
The definition of waste as well as its classification has been approached by various researchers. In general, researchers have commonly included defects and excess processing as some of the more common factors considered as waste (Senaratne & Wijesiri, 2008). Additionally, other factors have been mentioned in specific industries to broaden this classification. For instance, researchers have suggested “a broader definition of waste to include not only material waste, but also waste generated in a construction project such as waiting times, transportation times…” (Hosseini, Nikakhtar, Wong, & Zavichi, 2012, p. 415). The lean approach for the elimination of waste, as described by Ohno (1988), is as follows: “All we are doing is looking at the time line, from the moment the customer gives us an order to the point when we collect cash. And we are reducing that time line by removing the non-value-added wastes” (p. 9). The lean approach towards construction adopts both physical and non-physical waste production.
The waste associated with transportation consists of all kinds of material, component, and process transportations that are not necessary (Hosseini et al., 2012). Transportation refers to the movement of products from one place to another during production, which can be within one city or between countries (Jones & Womack, 2014). Such transportations do not add additional product value; rather, they are effects of inefficient factory layout.
The lean principle for manufacturing involves efficiency in transportation. This is done by ensuring the production layout is set such that there is no need for products to travel large distances (Forsberg & Saukkoriipi, 2007). In addition to adding no value to the product itself, transportation may lead to damage and delay. As a result, it is considered one of the types of waste in production process. The transportation waste causes financial spending to a manufacturing organization due to spending related to equipment handling, safety, staff, additional space, and training (Hicks, 2007). Transportation can result in delay in the product delivery process. As a result, the waste of transportation is associated with the waste of waiting. Transportation, by increasing delay, may cost organizations financial burden and lead to waste of time. Increased usage of transportation can also open up the possibilities of loss and damage related to handling (Senaratne & Wijesiri, 2008). Such possibilities, especially in the case of expensive products, may cause an organization excessive financial loss.
Research have suggested various causes that may lead to transportation waste. The most important cause for transportation waste is related to overproduction waste and inventory waste. The overproduction of goods results in inventory waste, which requires transportation between factories (Jones & Womack, 2014). There are many reasons that may cause overproduction, including lack of accurate predictions on demand. Transportation as a waste is affected by these factors.
As noted previously, the layout of a factory can be an important factor in causing transportation waste. Organizations are in general divided into separate parts, such as parts dedicated to different production activities. Such division presents the need for transportation of the product between different parts multiple times during and after the processing of specific activities. Further, transportation is not only a requirement in organizations which have separate facilities, as wide gaps between different operation areas may require the transportation of products during the production process (Forsberg & Saukkoriipi, 2007).
Researchers have suggested various strategies for minimizing or eliminating the waste resulting from transportation. As overproduction and inventory waste as associated with transportation waste, eliminating or minimizing the factors that cause these wastes can have a positive influence on reducing transportation waste (Bhamu & Sangwan, 2014). As layout of a factory maybe the most important factor causing transportation waste, designing a factory layout on the basis of lean principle of manufacturing has been suggested as the most efficient way to eliminate the problem of transportation waste (Lacerda, Xambre, & Alvelos, 2015). The lean principle of manufacturing, in the context of layout, refers to the development of production cells that include every process of interest in the production. The lean principle also includes having no large non-function gaps on a production line. Another method to improve the layout of a factory in lean principle is by using the mass production view towards production. Such method involves keeping equipment and machine together (Modi & Thakkar, 2014). This method can cause the maximization of transportation between production areas. The approach involves the classification of families of products and the grouping of different equipment on the basis of its product family. Such a grouping results in the achievement of a flow in production floor that can reduce the need for transportation.
Author: Henri Suissa
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