Exploring Lean in construction projects : How can the workflow be improved by observing value streams?

Sammanfattning: Research reveal that the construction industry does not have the same level of growth and development in performance compared to the manufacturing industry, and that Lean could be one solution to improve performance. Most research about Lean in the construction industry that exist today focus on simulating future scenarios. Hence miss analysing the impact Lean has on the current situation of construction projects, and its usability and possibility to set the framework for how to improve performances in construction projects. Thus, there is a gap in research concerning the evaluation on current process flows. This research explores Lean as a management method to understand how it has been used in the construction industry and how it could be used in construction projects to improve process flows. This will be done by using the method Value Stream Mapping, a method within Lean that is used to identify Non-Value-Adding activities in the process flow to point out what activities can be improved. The case study in this research explores two different value streams within two construction projects; deliveries and mounting one side of the framework of interior walls. Thus, the research will explore if and how the value stream differentiates between the two projects, with the aim to understand the reason for the results to understand how future construction projects could improve their process flows within a value stream. Data will be collected and analysed qualitative by combining observations and interviews. The value stream for deliveries differentiated between the projects. Project A had 73% Non-Value-Adding activities with a cycle time of 3,1 m2/min whilst Project B had 65% with a cycle time of 2,7 m2/min. In both projects Non-Value-Adding activities were categorized as Waiting, Movement, Transport and Overproduction. The value stream for mounting in Project A had 31% Non-Value-Adding activities with a cycle time of 2,9 m2/hour whilst Project B had 41% Non-Value-Adding activities with a cycle time of 1,7 m2/hour. In both project activities were categorized as Waiting, Transport, Incorrect processing and Movement. However, in Project B Overproduction was also identified as a Non-Value-Adding activity. Findings from the study shows that even though construction projects are complex and consist of variabilities, it is possible to observe value streams to identify Non-Value-Adding activities. Nevertheless, it is crucial to adjust the method to the construction industry since the theory of Value Stream Mapping originate from the manufacturing industry. This research recommends excluding number of resources as a category from the method and instead evaluate resources based on the total time, and to categorize inspections and reading drawing as Value-Adding activities instead of Non-Value-Adding. The study reveals that construction projects that work with Lean and its method Value Stream Mapping are given new opportunities to improve process flows. Thus, construction projects could be able to improve processes without needing to invest in more resources, material and tools. Not only could projects lower construction costs but also improve production time as Non-Value-Adding activities are reduced. Thus, the research believes Lean and its method Value Stream Mapping could improve performances within the construction industry.