## 1 Introduction  
The construction industry is unique in that the implementation of physical works is conducted primarily in the field, and thus site management is a key to the successful delivery of projects [1]. A construction project involves multiple stakeholders, including engineers, contractors, and vendors, who must make evaluations and decisions to maximize productivity while minimizing potential cost overruns and delays, as well as accidents and quality defects [2; 3]. Thus, it is essential to provide project managers with relevant project information in a timely and effective manner.  
Building Information Modeling (BIM) provides a fundamental basis for improving site management, as it enables a way to manage and integrate project data with design information in the form of 3D models [4]. It can also be used to represent the physical work in a virtual environment, enabling simulations of construction sequences to identify interferences, safety hazards, and potential delays [5]. The utility of BIM has been further improved by the introduction of Common Data Environments (CDE) [6], which provide a platform to share simulations and analyses of BIM models performed by multiple project participants.  
Until now, accessing BIM directly in the field has been limited [7; 8], with one of the reasons being attributed to the lack of an appropriate medium that allows access to the models readily and easily for personnel on-site [9]. It is also difficult to obtain and compare changing field conditions via BIM models. Indeed, [10] noted that existing BIM-based site management systems had not provided adequate solutions for intuitively utilizing BIM models in the field.  
Augmented Reality (AR), which allows the projection of 3D models and relevant information onto real-world scenes, has been explored by researchers in the construction domain to bridge this gap [11]. AR takes advantage of our natural ability to visually acquire knowledge and information [12]. In construction, AR can provide project information directly on-site, via tablets or head-mounted displays, and thus overcome the limitations associated with conventional BIM-based tools reliant on desktops [13]. Specifically, AR has the potential as a technological medium to access and share the information stored in BIM models.  
The authors of this study previously developed AROS (Augmented Reality-based On-Site), a system that enables site management by linking BIM with AR technology [14]. AROS is embedded with functionalities customized for field inspection needs, especially for quality and safety checks. Unlike existing AR studies that mainly focused on the architectural field [15; 16], AROS is customized for infrastructure projects. However, AROS and its functionalities have not been tested thoroughly by its potential users, nor for its robustness to meet the hardware and software restrictions of display devices.  
This study introduces the on-site experiments conducted using AROS to determine its efficacy and practical applicability. The experiments identified two technical issues to improve the projection stability and placement accuracy of the BIM models: (1) the need for model simplification and (2) the need for advanced anchoring techniques.  
This paper describes how these issues were addressed, improved, and verified. The results provide practical approaches to how model projections should be calibrated for BIM-based AR systems to work accurately and effectively.  
The rest of this paper is structured as follows. Section 2 introduces existing studies where AR has been used for site management, as well as state-of-the-art techniques for AR development. Section 3 provides a summary of the AROS system, while Section 4 explains the methodology used in this study to test and validate AROS in the field. Section 5 presents the two technical issues identified by the field experts, while Sections 6 and 7 describe the technical approaches adopted to resolve them, respectively. Finally, Section 8 presents a discussion of the results and their limitations.