Seohae Line

After the completion of planning, the project was written out as a build–lease–transfer (BLT) project, and Daewoo was selected^[3] as preferred bidder in September 2008.^[1] Construction was scheduled to last from October 2009 to March 2013.^[4] Due to the global financial crisis, it was difficult to gather investors to finance the project, and negotiations stalled.^[1] An agreement was finally signed on December 21, 2010, with construction set to start in the first half of 2011.^[1] 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.^[1]

The first section began construction in 2011 and opened on June 16, 2018.^[5]

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.

Another extension (Ilsan-Unjeong) was approved in January 2024.^[6] 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 (140 mph) the Wonsi–Hwayang extension is to be projected for 250 km/h (160 mph), and the line may see KTX service.^[7]

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.^[8][9] As of April 2023, the construction of this section was 92% completed and expected to be opened in the second half of 2024.^[10]

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.

Station Number	Station Name English	Station Name Hangul	Station Name Hanja	Transfer	Distance in km	Total Distance	Location
S07	Ilsan	일산	一山	(Shared)	---	0.0	Gyeonggi-do	Goyang-si
S08	Pungsan	풍산	楓山		1.9	1.9
S09	Baengma	백마	白馬		1.7	3.6
S10	Goksan	곡산	谷山		1.6	5.2
S11	Daegok	대곡	大谷		1.7	6.9
S12	Neunggok	능곡	陵谷		1.8	8.5
S13	Gimpo Int'l Airport	김포공항	金浦空港		7.4	15.9	Seoul	Gangseo-gu
S14	Wonjong	원종	遠宗		4.3	20.2	Gyeonggi-do	Bucheon-si
S15	Bucheon Stadium	부천종합운동장	富川綜合運動場		2.1	22.3
S16	Sosa (Seoul Theological Univ.)	소사 (서울신대)	素砂		2.7	25.0
S17	Sosaeul (Bucheon Univ. Sosa Campus)	소새울 (부천대 소사캠퍼스)	---		1.7	26.7
S18	Siheung Daeya	시흥대야	始興大也		2.1	28.8		Siheung-si
S19	Sincheon	신천	新川		1.4	30.2
S20	Sinhyeon	신현	新峴		3.3	33.5
S22	Siheung City Hall	시흥시청	始興市廳		3.6	37.1
S23	Siheung Neunggok	시흥능곡	始興陵谷		1.3	38.4
S24	Dalmi	달미	達味		2.4	40.8		Ansan-si
S25	Seonbu (Hando Hospital)	선부 (한도병원)	仙府		1.6	42.4
S26	Choji	초지	草芝		1.7	44.1
S27	Siu	시우	時雨		1.4	45.5
S28	Wonsi	원시	元時		1.5	47.0
S29	Int'l Theme Park (TBC)	국제테마파크	國際−					Hwaseong-si
S30	Seohwaseongnamyang (December 2024)	서화성남양	西華城南陽

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.^[11]

• Transportation in South Korea
• Korail