Seoul Subway Line 8 Extension 'Byeollae Line' Tunnel Passes Under Han River... 1280m Section from Gangdong Amsa to Guri Topyeong

Seoul Metro's Fourth Han River Underpass Completed... Safety Maintained, Construction Time Reduced by 3.5 Months
12.9 km Line with 6 Stations Including 2 Transfer Stations... 66% Progress, Completion Targeted for 2023

[Asia Economy Reporter Lim Cheol-young] Seoul City announced that at 3 p.m. on the 28th, it will complete the breakthrough of a 1,280m tunnel passing under the Han River between Amsa-dong, Gangdong-gu, and Topyeong-dong, Guri-si, on the Seoul Metro Line 8 extension (Byeollae Line) section connecting Amsa Station in Amsa-dong, Seoul, and Byeollae Station (Gyeongchun Line).

The Seoul Metro lines passing under the Han River include the Seoul Metro Line 5 section from Gwangnaru Station to Cheonho Station, the section from Mapo Station to Yeouinaru Station, the Bundang Line section from Apgujeong Rodeo Station to Seoul Forest Station, and the Line 8 extension section, making it the fourth such urban railway tunnel under the Han River.

The Line 8 extension (Byeollae Line) section starts from Amsa Station (Amsa-dong, Gangdong-gu), the current terminus of subway Line 8, passes under the Han River, and goes through the Guri-si section. It extends 12.906 km to Byeollae-eup, Namyangju-si, with six stations including two transfer stations: Guri Station (Gyeongui-Jungang Line) and Byeollae Station (Gyeongchun Line). The total project cost is 1.3403 trillion KRW.

Among the six construction sections, Sections 1 and 2 (3.72 km), which pass underground from Amsa-dong under the Han River to Topyeong-dong, Guri-si, are being implemented by Seoul City. The total project cost is 521.4 billion KRW, with completion targeted for 2023. As of June 2021, the construction progress rate is 69%.

The Byeollae Line Han River Underwater Tunnel consists of separate tunnels for the up and down lines. Tunnel excavation using the shield TBM method began in December 2019 from Topyeong-dong, Guri-si, and after nine months, in August 2020, the down line (towards Amsa-dong, Gangdong-gu) was completed. The shield TBM tunneling method involves rotating a cylindrical cutter head to crush rock into small pieces and excavate horizontally, then assembling precast concrete segments to construct the tunnel.

After equipment disassembly, relocation, and maintenance, excavation of the up line (towards Amsa-dong, Gangdong-gu) began in December 2020 from Topyeong-dong, Guri-si, and was completed in June 2021, seven months later. Due to geological characteristics such as joints and fault fracture zones in the ground, the Han River underwater section is a challenging area with high water pressure on the tunnel, but the project was completed about 3.5 months ahead of schedule without any safety accidents.

Kim Jin-pal, Director of Seoul City Urban Infrastructure Headquarters, said, “Travel time from Byeollae, Namyangju-si to Jamsil, Songpa-gu will be reduced to 27 minutes, about 17 minutes shorter than using existing urban rail lines. Connecting Byeollae, Namyangju-si and Guri-si directly to Amsa-dong, Gangdong-gu will improve accessibility to the Seoul Gangnam area for residents in the northeastern metropolitan area.”

This content was produced with the assistance of AI translation services.