## 1 Introduction  
The rapid development of South Korea has been accompanied by the construction of various infrastructure facilities. Among these, bridges play a critical role in transportation, logistics and transit. Different departments, such as the Facility Management System (FMS) and the Bridge and Tunnel Information System (BTI), are involved in the operation and management of these structures. The FMS manages comprehensive infrastructure, including bridges, tunnels and retaining walls, while the BTI focuses specifically on bridges and tunnels. The status of facilities managed by the FMS is presented in Table 1[1]. Excluding buildings, bridges account for approximately 57.2% of the social infrastructure. As listed in Table 2[1], bridges are classified into three types (Type 1, Type 2 and Type 3) based on their length and form. After the collapse of the Seongus Bridge on 21 October 1994, South Korea enacted several laws to improve bridge maintenance, including the \"Special Act on the Safety Control and Maintenance of Establishments\", the \"Framework Act on Sustainable Infrastructure Management\" and the \"Detailed Guidelines for the Safety and Maintenance of Facilities\" [2; 3; 4]. Significant efforts, including meticulous inspections and the implementation of self-management systems, are invested in maintaining Type 1 bridges, which are classified as major social infrastructure. However, most bridges in South Korea are Type 2 and Type 3, and their maintenance is relatively neglected compared to Type 1 bridges. Therefore, establishing relevant safety measures is necessary. According to the BTI, South Korea has a total of 38,598 bridges. Among them, reinforced concrete (RC) slab bridges (including RC hollow slab bridges) account for approximately 24.1% of all bridges (Figure 1), making them the most common type of bridge in the country. As shown in Figure 2, approximately 87.1% of these RC slab bridges are over 20 years old, indicating significant aging. Additionally, as depicted in Figure 3, approximately 89.9% of the bridges are less than 20 m long, indicating that most are small-to-medium sized [5]. In South Korea, the maintenance of small- to medium-sized RC slab bridges relies on condition assessments. This involves visual inspections of the target bridge and expressing the results as a quantitative grade from A to E. Although an accurate evaluation requires structural analysis, budget and personnel constraints hinder conducting structural analysis for all in-service bridges during each maintenance cycle. Looking at bridge inspection standards abroad, in the UK, Safety Inspections and Special Inspections are carried out based on the needs of the managing agency, while General Inspections and Principal Inspections are conducted periodically. General Inspections involve only visual inspection without the use of inspection vehicles or access equipment. In contrast, Principal Inspections involve a more detailed assessment of the bridge's condition from close range using inspection equipment and vehicles when necessary. In Japan, only regular inspections are mandated for bridges. According to the Bridge Regular Inspection \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Facility**} & \multicolumn{4}{c}{**Type**} & \multirow{2}{*}{**Total**} \\ \cline{2-2} \cline{4-5}  & & **1** & **2** & **3** & **3** \\ \hline Bridge & 5235 & 7760 & 21,877 & 34,872 \\ Tunnel & 2016 & 2353 & 855 & 5224 \\ Port & 174 & 445 & - & 619 \\ Dam & 120 & 569 & - & 689 \\ Building & 3644 & 77,889 & 30,404 & 111,937 \\ River & 650 & 6465 & 20 & 7135 \\ Water and sewage & 579 & 1791 & 1 & 2371 \\ Retaining wall & - & 3841 & 722 & 4563 \\ Cut slope & - & 4782 & 1 & 4783 \\ Utility–Pipe & - & 50 & - & 50 \\ conduit & - & - & 626 & 626 \\ Others & - & - & 626 & 626 \\ Sum & 12,418 & 105,945 & 54,506 & 172,869 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Status of infrastructure facilities in South Korea (as of 23 January 2024).