On the 11th, regarding the construction site collapse of the Shin Ansan Line double-track railway in Gyeonggi Province's Gwangmyeong City, it has been revealed that there were multiple warnings about ground subsidence. Warnings from environmental impact assessment agencies were issued as early as 2020, during the early stages of the project. Moreover, right before the accident, damage to the central pillar of the tunnel was confirmed, yet workers were not evacuated. Experts point out that rush work to meet construction deadlines and reduce costs may have contributed to the accident. As a result, there is a possibility that the responsibility of the contractor NextTrain and the construction company POSCO Engineering & Construction may come to the forefront for ignoring repeated warnings.
According to the Ministry of Land, Infrastructure and Transport, the National Assembly's Land and Transportation Committee, and the industry on the 14th, the first warning regarding the site of the accident on the 11th was raised in the 'Shin Ansan Line double-track railway (Main Line section 1) private investment project environmental impact assessment report,' which was conducted from 2019 to 2020. In July 2019, the Ministry of Land conducted an environmental impact assessment of this site. Later, in 2020, reflecting the adjacent 'Ansan Jang-sang public housing project,' the 4.653 km stretch from Wulpi-dong in Ansan's Sangnok-gu to Joanam-dong in Siheung City was redesigned, and the environmental impact assessment was revised through consultation.
Of particular note regarding this incident are the opinions submitted by the Ministry of Environment and the Korea Environment Policy Evaluation Institute during the environmental impact assessment at that time. The Ministry of Environment noted, "This project plans to install numerous facilities in the underground space of city sections," adding, "There are concerns about structural stability issues such as ground subsidence due to large-scale groundwater discharge and the impact on nearby groundwater facilities (decline in water levels)." The Korea Environment Policy Evaluation Institute also presented an opinion suggesting the need for a thorough review of the environmental impacts (decline in groundwater levels, ground subsidence, etc.) due to groundwater discharge during construction and operation of the underground section of the planned route. In response, the contractor submitted a plan stating, "We will review the environmental impact (decline in groundwater levels, ground subsidence, etc.) due to groundwater discharge during construction and operation." This suggests that the possibility of ground subsidence was already raised in environmental impact assessments conducted 5 to 6 years ago.
There are also criticisms that precursory symptoms before the accident were ignored. According to the initial situational report on the accident obtained by Democratic Party lawmaker Moon Jin-seok, a central pillar damage of the "Two-arch" tunnel was confirmed at 9:50 p.m. on the 10th, the day before the accident, prompting workers to evacuate. The Gwangmyeong Police Department began controlling traffic lanes on the upper road from 12:40 a.m. on the 11th, approximately three hours after the damage to the pillar was confirmed. However, work for safety inspections and reinforcing construction continued in the underground tunnel and upper road, resulting in the collapse of the tunnel and the occurrence of missing persons.
Experts raise the possibility that reckless work to reduce construction costs and meet deadlines may have led to the accident. Lee Song-kyu, chairman of the Korea Safety Experts Association, stated, "The fact that the tunnel pillar was damaged indicates that the collapse had already begun," and added, "The site manager or supervision company should have stopped work immediately after confirming the damage, but action was insufficient. It seems that this was due to the constraints of the construction deadline."
There are also criticisms related to the 'Two-arch construction method' applied in the Shin Ansan Line project. Generally, a tunnel is excavated using one arch (a curved structure) on top. However, the Two-arch method involves creating two arches and constructing a pillar at the junction where the arches meet. The current incident occurred due to the collapse of the central pillar, which is essential in the Two-arch method.
Professor Jeong Hyuk-sang of Dongyang University’s Department of Railway Construction Safety Engineering explained, "When there is one arch, the load is dispersed along the arch's shape, but in the Two-arch structure, the load comes in toward the center, and it is a structure that supports the central pillar." He added, "When there are two arches, the large cross-section in the middle does not need to be excavated, which reduces construction costs, but accidents involving the collapse of the central pillar frequently occur," and noted, "We must not repeat the accidents that have occurred with the Two-arch method and strengthen safety, but it seems that there were shortcomings in this regard."
Meanwhile, the Ministry of Land, Infrastructure and Transport has formed a disaster response headquarters involving Vice Minister Baek Won-guk, the Ministry of Employment and Labor, Gyeonggi Province, Gwangmyeong City, the National Railroad Authority, and the contractor NextTrain to address the accident and investigate the facts. NextTrain is the contractor, and POSCO Engineering & Construction is the representative investor for NextTrain. The construction companies involved are POSCO Engineering & Construction and SEOHEE CONSTRUCTION, with the project management firms being Dongmyeong Technology Corporation, Seohyun Technology Group, and Samba Technology Group. The project began in 2019 and is scheduled to continue until next year, with a total project cost of 4.1047 trillion won. The current progress rate stands at 55.05%.