# BIM-Based Management System for Off-Site Construction Projects
## 1 Introduction
As 80-95% of OSC production occurs offsite, stocking, outgoing, transporting (to the site), and loading activities must be appropriately performed [27; 28]. To ensure the efficiency of the offsite tasks, OSC projects necessitate the management of each stage of production, logistics, and installation and the integration of SCM in each stage. The success of the OSC project relies on these management activities and appropriate systems [29]. Specifically, the efficiency and productivity of each work process must be improved through the integrated management of the project [30]. Management tools limited to specific goals (e.g., scheduling, costing, monitoring, and establishment) are somewhat challenging to manage as a whole for the OSC projects with highly diversified management elements. Moreover, the existing systems are mainly specialized for the managing of onsite work and thus cannot appropriately optimize OSC projects, in which most of the tasks are performed offsite. Building information modeling (BIM) technologies are promising for managing OSC projects. Since its introduction in the construction industry in the early 2000s, BIM has been applied to numerous projects and achieved encouraging results [31]. BIM is being actively implemented in design fields such as basic design, visualization, MEP, and interference checks, as it can handle three-dimensional (3D) information [32]. Recently, with the convergence of digitalization and automation technologies, BIM has been used to manage the schedule, cost, safety, and quality in order to enhance the project performance [33]. BIM technologies can facilitate the management of OSC projects [34], especially in terms of the SCM, which is the core of OSC projects, by integrating the vast amount of information generated within the building project [35]. In addition, BIM can facilitate collaboration between the participants in OSC projects [36; 37]. The participants can work with high-quality and detailed designs through design for manufacture and assembly (DfMA) techniques at an early stage and collaborate to achieve various objectives, such as time, cost, and progress management in the construction stage [38]. Considering these aspects, this study was aimed at using the BIM technology to establish a management system for OSC projects. The development followed the waterfall model,also known as the linear sequential model, and the paper was also organized according to each stage of the waterfall model--requirements analysis, design and implementation, and testing. First, recent trends in the BIM-based project system development and OSC project management, which differs from that of traditional construction projects, were examined, and the literature relevant to the OSC project management systems was reviewed. Prior to the system development, the authors examined the characteristics of OSC projects through case studies and expert interviews and subsequently derived the management requirements. The system environments and functions were implemented using various BIM components and application programming interfaces (APIs). Finally, the proposed system was applied to ongoing OSC projects for a certain period and evaluated, and the effectiveness of the management system based on BIM was demonstrated.