Slöserijakt i betongdjungeln
En tidseffektivisering av monteringsprocessen inom stål- och betongprefab
The different aspects of each individual construction project such as the general conditions, design and economic restrictions as well as many more factors mean it is difficult to standardize building processes or plan in detail based on past experiences. As a result operational efficiency is often reduced, and unnecessary waste is generated. To make an organization more efficient and therefore reduce waste production everybody involved needs to appreciate and understand the improvements that can increase the organization?s efficiency. To investigate these improvements a time study was performed on two different construction sites, both of which involved buildings being constructed of prefabricated steel and concrete elements. All activities that required cranes were recorded and afterwards identified as waste or non-waste. The identification of waste is a part of ?lean production? and its philosophy. In lean production, there are eight defined waste categories: over-production, waiting, transporting, over-processing, inventory, motion, defects and unused expertise. Put simply, lean production is about creating more value for customers with fewer resources. The purpose of this essay is to identify the largest and most frequently occurring wastes of crane time, and then the appropriate actions to reduce or eliminate that wastage. The study was conducted over two different weeks at two different construction sites, which equates to 2 400,0 minutes on each project. During the time study, each moment where the cranes were used was recorded. Execution time, type of lifting, quantity, reason for delay and waste category serves as the structural basis in the time study. The results show that the two most frequently occurring wastages were waiting and inventory, and the most common reasons for crane inefficiencies were preparation, inefficiency before and after breaks, and errors caused by external factors. It was also shown that non-productive craning represented 48 % of the total crane activity. Inventory of prefabricated elements and absence of elevator were the two most common wastages due to non-productive craning. Results and discussion led to the conclusion that the average ?wasted? time was 919,8 minutes per construction site and per working week. The identified waste could be reduced or eliminated by taking the right actions in the long term. The conclusion also shows that it is possible eliminate 393,5 minutes of waste to, in the short term, which would mean improvement by 393,5 minutes per working week and project.