Seoul Metropolitan Government announced that it will start construction of the tunnel under the Han River today (Thursday) to build the section between Amsa-dong and Guri-si Topyeong-dong, Gangdong-gu, on the extension of subway line 8. The extension of subway line 8 (Byeolnae) starts from Amsa Station in Gangdong-gu, passes through Guri-si, Gyeonggi-do and extends 12.9km to Namnaeju-si Byeolnae-dong. Six stations will be constructed.

The  part in Han River basin will have the tunnel depth 52m and the length of  1,279m. The Han River Basin Tunnel section is a very dangerous and difficult construction section with an atmospheric pressure of up to 4.7 times at a depth of 52m (bottom) from the surface. The pressure (earth pressure and water pressure) of the tunnel penetrating 1,279m of total length is expected to reach 4.7bar (Kg / cm²).

For the tunnel construction the Tunnel Boring Machine will be used for environmental and efficiency reasons. It is bored from Gupyeong Topyeong-dong to Amsa-dong, Gangdong-gu. It is scheduled to be completed in September 2023.
 

https://www.youthassembly.kr/news/50725