## 1 Introduction  
As more and more road collapse accidents are occurring in densely populated urban areas, national interest in managing underground facilities and buried pipes is increasing. As more people live in urban areas, transportation facilities, such as subways and underpasses, and utility pipes (water, sewage, telecommunications, and electricity) have been constructed without systematic planning, increasing the risk of road subsidence. In particular, the risk and frequency of road cave-ins have increased in recent years due to the accelerated aging of such facilities [1].  
A recent study on road subsidence in Seoul, Korea, found that about 4700 road cave-ins occurred from 2010 to 2016, and this trend increased year by year [2]. In Seoul, more than 80% of road cave-ins were caused by damage to sewer pipes. In Japan, 30-50% of road subsidence accidents from 1999 to 2009 were caused by damage to sewer pipes, and the risk of subsidence increased rapidly when the age or service life of sewer pipes exceeded 30 years [3].  
In 2015, the Korean government conducted a detailed inspection of old pipes in response to frequent road subsidence accidents. Accounting for 30% of all sewage pipes nationwide, approximately 40,000 km of old pipes aged over 20 years were inspected. The Ministry of Environment published a Sewer Pipeline Standard Inspection Manual (2015) specifying how to diagnose the inside of old pipes [4]. However, this direct inspection of underground pipelines had limitations in predicting the risk of road cave-ins nationwide due to budget and time constraints. Accordingly, Korea has promulgated the (Special Act on the Safety Management of Underground Facilities). The Act calls for preventing urban disasters caused by subsidence and managing underground facilities and is planned for implementation. The government is also preparing an integrated underground space map and underground space safety management system as part of establishing an underground safety information system. In addition, many studies have been conducted to investigate the mechanism of road subsidence and analyze the risk to prevent such accidents. Studies have been pursued to identify the mechanism of road subsidence by simulating ground cavities and relaxation zones using the finite element method [5]. This has also included investigating the mechanism of ground cavities by simulating sewer pipe cracks using model tests in sandy soil and visualizing the occurrence of ground cavities using X-ray and CT [6]. In addition, studies using decision tree analysis (a machine learning algorithm) were conducted to derive the factors affecting ground subsidence, calculate their weight [7], and predict the risk of ground subsidence using the attributes of underground utilities [8]. As such, many studies have been conducted to prevent road cave-ins. Therefore, this study evaluated the risk of road subsidence caused by sewer pipes, one of the primary causes of such accidents, based on the integrated facility information managed by the Ministry of Land, Infrastructure and Transport in Korea. The influencing factors for risk assessment were derived by analyzing the correlation between road subsidence and various aspects of information. These include pipe ID (Identifier), installation year, pipe type, pipe diameter, length, burial depth, exploration results, drainage method, and management agency based on GIS data from the integrated map of underground space. In addition, a methodology to assess the risk of road subsidence was presented by selecting the optimal analysis technique and evaluation method based on logistic regression and AHP (Analytic Hierarchy Process) analyses of the influencing factors.  
To verify the reliability of the proposed method for assessing road subsidence risk, this study compared and analyzed the actual incidence of road subsidence and the risk assessment results using sewer pipe information in a pilot study area.