Seohae Line

The Seohae Line is a dual-track, electrified rail line in western Gyeonggi-do and Seoul, South Korea. The Seohae Line is being built in four sections simultaneously. The line runs 47 km south from Ilsan in Goyang City, crosses the Han River, passes Gimpo Airport, Sosa, Siheung, and ends in Wonsi in Ansan. There is a transfer to different lines at Daegok, Neunggok, Gimpo Int'l Airport, Bucheon Stadium, Sosa and Choji. There are currently 21 stations (Ilsan-Wonsi). The line is operated by Korail, but the stations between Sosa and Wonsi are managed by SEO HAE RAIL CO.,LTD., which is a subsidiary of Seoul Metro. The infrastructure is also owned by Korail so the line runs on the left like the rest of the South Korean mainline railway network.

History
After the completion of planning, the project was written out as a build–lease–transfer (BLT) project, and Daewoo was selected as preferred bidder in September 2008. Construction was scheduled to last from October 2009 to March 2013. Due to the global financial crisis, it was difficult to gather investors to finance the project, and negotiations stalled. An agreement was finally signed on December 21, 2010, with construction set to start in the first half of 2011. Project costs are 1.5248 trillion South Korean won, the contractor has altogether seven years for design and construction, and will manage and maintain the line for the first 20 years of operation.

The first section began construction in 2011 and opened on June 16, 2018.

The second section runs north from Sosa to Daegok on the Gyeongui-Jungang Line and Seoul Subway Line 3. There are transfers to several other lines. It was expected to open on June 29, 2021, but did not open until July 1, 2023.

Another extension (Daegok-Ilsan) was opened at the end of August 2023.

Future
Another extension (Ilsan-Unjeong) was approved in January 2024. There is currently no opening date noted.

On September 1, 2010, the South Korean government announced a strategic plan to reduce travel times from Seoul to 95% of the country to under 2 hours by 2020. As part of the plan, the first section is to be further upgraded for 230 km/h the Wonsi–Hwayang extension is to be projected for 250 km/h, and the line may see KTX service.

Tentative plans foresee the upgrade and incorporation of the Gyooe Line, a single-track non-electrified line without passenger service that connects Neunggok station (with a junction just before Daegok station) and Uijeongbu station in Uijeongbu. The Uijeongbu–Daegok–Sosa–Wonsi Line would then provide orbital metro service as a northern semicircle around Seoul, complementing the southern semicircle formed by the Suin–Bundang Line.

Another part of the tentative 2010 plans was a southern extension from Wonsi, connecting up with the Janghang Line before Hongseong station. As of April 2023, the construction of this section was 92% completed and expected to be opened in the second half of 31 October 2024.

Urban section
The section from Sosa to Wonsi opened on June 16, 2018. The first phase (Sosa to Daegok) of the Sosa to Ilsan extension opened on July 1, 2023. The second phase (Daegok to Ilsan) of the Sosa to Ilsan extension opened on August 26, 2023. The line currently utilizes seven four-car Class 391000 trains manufactured by Hyundai Rotem and ten four-car Class 391000 trains manufactured by Dawonsys.

The line is being extended southward from Wonsi to Seohwaseongnamyang. Station names may be subject to change as the line is constructed and various sources give conflicting information.