The forerunner of the Sinansan Line was Line 10, proposed in 1994 as part of Seoul Metro's Phase 3 expansion but was mostly unbuilt due to the
1997 Asian financial crisis. Originally Line 10 was also planned to extend east beyond downtown Seoul going through either Sinchon, Dongnimmun and Hyehwa or pass through Gongdeok, Seoul Station and Dongdaemun Stadium. However, following the restoration of the
Cheonggye Stream, under which Line 10 was planned to be laid, the former route seems much more likely. The Sinansan Line underwent many design changes during planning stages, but generally the line was envisioned to run between
Sinpung and
Gwangmyeong station. In particular, the section south of Gwangmyeong station has led to heated disputes between the cities of
Ansan and
Siheung. Ansan has requested for the line to be built almost perfectly south from Gwangmyeong station so it terminates at Hanyang Univ. ERICA Campus, passing through Seongpo-dong on the way. This would also open the possibilities for the trains on this line to travel to
Suwon via the
Suin Line. The consortium behind the construction of the Sin Ansan Line, however, favors a line running southwest from Gwangmyeong station and joining the Sosa-Wonsi Line, transferring with
Line 4 and the
Suin Line at
Choji station and terminating at southwestern Ansan. The city of Siheung proposed the section in dispute does not even pass through the city of Ansan at all, making the name "Sin
ansan Line" meaningless. The Siheung plan has the section go west from Gwangmyeong station, intersect the Sosa-Wonsi Line at Siheung City Hall, and terminating at
Wolgot station. Construction was planned to begin in 2015 with the first section of this line (Gwangmyeong station - Yeouido) is set to be opened in 2023. However, contract disputes between the Ministry of Land, Transport and Maritime Affairs and the preferred operator delayed the project and lead to a retendering. Construction of Phase 1 (Yeouido to Hanyang University/Songsan stations) began 2019 September 9. ==History==