Line 4
Seoul Metro 4000 series EMU in July 2023 Korail Class 341000 series EMU in April 2020
Overview
Native name	4호선(四號線) Sa Hoseon
Status	Operational
Termini	Jinjeop Oido
Stations	51 26-Seoul Metro 22-Korail 03-Namyangju City Urban Corporation
Service
Type	Rapid transit
System	Seoul Metropolitan Subway
Operator(s)	Seoul Metro, Korail, Namyangju City Urban Corporation
History
Opened	20 April 1985 (1985-04-20)
Technical
Line length	72.1 km (44.8 mi) 31.7 km (19.7 mi) Seoul Metro[1] 40.4 km (25.1 mi) Korail[2]
Number of tracks	2
Electrification	1,500 V DC (Jinjeop to Namtaeryeong) 25 kV AC at 60 Hz (Seonbawi to Oido)
Operating speed	100 km/h (62 mph)

Seoul Subway Line 4 (dubbed The Light Blue Line) of the Seoul Metropolitan Subway is a long line crossing from the southwest to the northeast across the Seoul National Capital Area. The central section in Seoul City is operated by Seoul Metro with some trains offering through service to Korail's Ansan and Gwacheon Lines.^[3] The southern terminus (Oido) is in Jeongwang 4-dong, Siheung City, and the northern terminus (Jinjeop) is in Jinjeop-eup, Namyangju-si, Gyeonggi-do; the newly built northern section (officially called the Jinjeop Line) is correspondingly owned by a company owned by Namyangju-si, with operations contracted to Seoul Metro. In 2022, the Seoul Metro operated section had an annual ridership of 219,587,000 or about 601,608 passengers per day.^[4]

Northbound trains that run on the Ansan and Gwacheon Lines terminate at Danggogae, except during night time where they short-turn at various stations. Southbound trains that run on the Ansan and Gwacheon Lines terminate at Oido or Ansan. All trains from Jinjeop short-turn at Sadang, though some short-turn trains to Sadang start at Danggogae or terminate one station south at Namtaeryeong.

Express train service stops at all stations between Danggogae and Sanbon, then at Sangnoksu, Jungang, Choji, Ansan, Jeongwang, and Oido. The express service only operates during rush hours on weekdays.

History

1985:

20 April: Line 4 is officially opened from Sanggye to Samseon-gyo.

1993:

21 April: The line is extended northward from Sanggye to Danggogae.

1994:

1 April: The line is extended southward from Sadang to Ansan when a section of the Gwacheon Line (from Seonbawi to Indeogwon) and Namtaeryeong Station open.

2000:

28 July: The line is extended westward from Ansan to Oido.

2003

18 July: Surisan Station opens as an in-fill station on the Ansan Line section.

2010

Ansan Line AM express service is launched in the northbound direction only (starting from Ansan). Trains stopped at Jungang, Sangnoksu, and Sanbon, before continuing local up to Danggogae.

2014

1 September: Southbound PM express service is launched (terminating at Ansan). Trains make the same stops as their AM express service counterparts.

2017

7 July: Express service is extended to Oido. In addition to the stops they made before, trains make all stops between Ansan and Oido.

2020

12 September: Express service is modified, with trains now stopping at Choji but skipping Singiloncheon.

2022:

19 March: The Jinjeop Line, a northward extension of Line 4, opens from Danggogae to Jinjeop.^[5]

Future

Express services are planned to start skipping various stations north of Sanbon station by 2023 to cut travel times.^[6]

Stations

Station Number	Station Name English	Station Name Hangul	Station Name Hanja	EX	Transfer			Line Name	Distance in km	Total Distance	Location
405	Jinjeop (Kyungbok University)	진접 (경복대)	榛接					Jinjeop Line	---	0.0	Gyeonggi-do	Namyangju-si
406	Onam	오남	梧南						2.1	2.1
407	Pungyang (2026)	풍양	豊壤						2.6	4.7
408	ByeollaeByeolgaram	별내별가람	別內별가람						5.2	9.9
409	Danggogae	당고개	당고개	Makes all stops				Seoul Metro Line 4	4.4	14.3	Seoul	Nowon-gu
410	Sanggye	상계	上溪						1.2	15.5
411	Nowon	노원	蘆原						1.0	16.5
412	Chang-dong	창동	倉洞						1.4	17.9		Dobong-gu
413	Ssangmun	쌍문	雙門						1.3	19.2
414	Suyu (Gangbuk-gu Office)	수유 (강북구청)	水踰						1.5	20.7		Gangbuk-gu
415	Mia (Seoul Cyber Univ.)	미아 (서울사이버대학)	彌阿						1.4	22.1
416	Miasageori	미아사거리	彌阿사거리						1.5	23.6
417	Gireum	길음	吉音						1.3	24.9		Seongbuk-gu
418	Sungshin Women's Univ. (Donam)	성신여대입구 (돈암)	誠信女大入口						1.4	26.3
419	Hansung Univ. (Samseongyo)	한성대입구 (삼선교)	漢城大入口						1.0	27.3
420	Hyehwa (Seoul Nat’l Univ. Hospital)	혜화 (서울대학교병원)	惠化						0.9	28.2		Jongno-gu
421	Dongdaemun	동대문	東大門						1.5	29.7
422	Dongdaemun History & Culture Park (DDP)	동대문역사문화공원 (DDP)	東大門歷史文化公園						0.7	30.4		Jung-gu
423	Chungmuro	충무로	忠武路						1.3	31.7
424	Myeong-dong (Woori Financial Town)	명동 (우리금융타운)	明洞						0.7	32.4
425	Hoehyeon (Namdaemun Market)	회현 (남대문시장)	會賢						0.7	33.1
426	Seoul Station	서울역	서울驛		(Seoul Station branch) Mugunghwa-ho and ITX-Saemaeul services				0.9	34.0		Yongsan-gu
427	Sookmyung Women's Univ. (Garwol)	숙대입구 (갈월)	淑大入口						1.0	35.0
428	Samgakji	삼각지	三角地						1.2	36.2
429	Sinyongsan (AMOREPACIFIC)	신용산 (아모레퍼시픽)	新龍山						0.7	36.9
430	Ichon (National Museum of Korea)	이촌 (국립중앙박물관)	二村						1.3	38.2
431	Dongjak (Seoul National Cemetery)	동작 (현충원)	銅雀						2.7	40.9		Dongjak-gu
432	Chongshin Univ. (Isu)	총신대입구 (이수)	總神大入口						1.8	42.7
433	Sadang (Daehang Hospital)	사당 (대항병원)	舍堂						1.1	43.8
434	Namtaeryeong	남태령	南泰嶺						1.6	45.4		Seocho-gu
435	Seonbawi	선바위	선바위					Gwacheon Line	2.0	47.4	Gyeonggi-do	Gwacheon-si
436	Seoul Racecourse Park	경마공원	競馬公園						1.0	48.4
437	Seoul Grand Park (Seoul Land)	대공원 (서울랜드)	大公園						0.9	49.3
438	Gwacheon	과천	果川						1.0	50.3
439	Government Complex Gwacheon	정부과천청사	政府果川廳舍						1.0	51.3
440	Indeogwon	인덕원	仁德院						3.0	54.3		Anyang-si
441	Pyeongchon (Hallym Univ. Sacred Heart Hospital)	평촌 (한림대성심병원)	坪村						1.6	55.9
442	Beomgye	범계	범계						1.3	57.2
443	Geumjeong	금정	衿井					Ansan Line	2.6	59.8		Gunpo-si
444	Sanbon (Wonkwang Univ. Sanbon Hospital)	산본 (원광대산본병원)	山本	●					2.3	62.1
445	Surisan	수리산	修理山	|					1.1	63.2
446	Daeyami	대야미	大夜味	|					2.6	65.8
447	Banwol	반월	半月	|					2.0	67.8		Ansan-si
448	Sangnoksu (Ansan Univ.)	상록수 (안산대학교)	常綠樹	●					3.7	71.5
449	Hanyang Univ. at Ansan	한대앞	漢大앞	|		Suin–Bundang (shared)			1.5	73.0
450	Jungang (Seoul Institute of the Arts)	중앙 (서울예술대)	中央	●					1.6	74.6
451	Gojan (Korea Univ. Ansan Hospital)	고잔 (고대안산병원)	古棧	|					1.4	76.0
452	Choji (Shin Ansan Univ.)	초지 (신안산대)	草芝	●					1.5	77.5
453	Ansan	안산	安山	●					1.8	79.3
454	Singiloncheon	신길온천	新吉溫泉	|					2.2	81.5
455	Jeongwang (Tech Univ. of Korea)	정왕 (한국공학대)	正往	●					2.9	84.4		Siheung-si
456	Oido	오이도	烏耳島	●					1.4	85.8

Seoul Metropolitan Subway Line 4
Legend
405 Jinjeop Jinjeop Depot (Transferred from Chang-dong Depot) 406 Onam 407 Pungyang Wangsukcheon Bridge 408 ByeollaeByeolgaram Northbound turnback   409 Danggogae ( ↑ Jinjeop Line ↓ Seoul Subway Line 4 ) 410 Sanggye 411 Nowon Chang-dong Depot 412 Chang-dong 413 Ssangmun 414 Suyu 415 Mia 416 Miasageori 417 Gireum 418 Sungshin Women's Univ. 419 Hansung Univ. 420 Hyehwa 421 Dongdaemun 422 Dongdaemun History & Culture Park Link with Line 3 423 Chungmuro 424 Myeong-dong 425 Hoehyeon 426 Seoul Station Cancelled link with Line 1 427 Sookmyung Women's Univ. 428 Samgakji 429 Sinyongsan 430 Ichon Dongjak Bridge crossing Hangang river 431 Dongjak 432 Chongshin Univ. 433 Sadang Southbound turnback for DC only trains   434 Namtaeryeong ( ↑ Seoul Subway Line 4 ↓ Gwacheon Line ) Right-hand running/1.5kV DC/Seoul Metro Section Left-hand running/25kV AC/Korail Section changeover 435 Seonbawi 436 Seoul Racecourse Park 437 Seoul Grand Park 438 Gwacheon 439 Government Complex Gwacheon 2027 Gwacheon Information Town 440 Indeogwon 441 Pyeongchon 442 Beomgye Line 1 and Gyeongbu Line to Kwangwoon Univ. and Seoul Station 443 Geumjeong ( ↑ Gwacheon Line ↓ Ansan Line ) Line 1 and Gyeongbu Line to Seodongtan or Sinchang and Busan 444 Sanbon 445 Surisan Suwon-Munsan Expressway 446 Daeyami Yeongdong Expressway 447 Banwol Seohaean Expressway Gyeongbu HSR 448 Sangnoksu Suin Line (Suin-Bundang Line) towards Wangsimni/Cheongnyangni via Suwon 449 Hanyang Univ. at Ansan 450 Jungang 451 Gojan 452 Choji link with Seohae Line 453 Ansan 454 Singiloncheon Pyeongtaek-Siheung Expressway 455 Jeongwang 456 Oido Siheung Depot Suin Line (Suin-Bundang Line) towards Incheon Shared with Suin-Bundang Line between Hanyang Univ. at Ansan to Oido
Express services (Rush hours only) All Stations to Danggogae 443 Geumjeong 444 Sanbon Surisan, Daeyami, Banwol 448 Sangnoksu Hanyang Univ. at Ansan 450 Jungang Gojan 452 Choji 453 Ansan Singiloncheon 455 Jeongwang 456 Oido

Depots, junctions, and points of interest

(from Jinjeop to Oido)

• Jinjeop Depot (opening December 2024, will replace Changdong Depot for Seoul Metro-operated rolling stock)
• Turnback siding (underground) after Danggogae Station
• Changdong Depot (used for Seoul Metro class 4000, with non-revenue connection to Line 1)
• Non-revenue connecting track to Line 3 before Chungmuro Station
• Dongjak Bridge
• Chongshin Univ. – Sadang scissors crossover
• Hanyang University, ERICA Campus
• Turnback siding (underground) after Sadang Station
• Namtaeryong–Seonbawi track crossing point (flying crossover, switch from right to left-hand traffic, or vice versa)^[a]
  • The voltage/current switches between DC 1,500 V ↔ AC 25,000 V
• Non-revenue crossover to Line 1 after Geumjeong Station
• Non-revenue connecting track to Seohae Line before Choji Station
• Ansan Depot (used for simple maintenance of Korail Class 341000 train)
• Siheung Depot (used for Korail Class 341000 maintenance and also for heavy maintenance of Korail Class 311000 trains operated on Line 1)
• The largest scale of shell mounds in the South Korean west coast in Oido

Rolling stock

Current

Seoul Metro

• Seoul Metro 4000 series
  • 1st generation, DC only: 4-01~4-26 (Restricted to Jinjeop-Sadang)
  • 1st generation, DC & AC: 4-51~4-71 (Retirement in Process)
  • 2nd generation: 4-81~4-85
  • 3rd generation: 4-50~4-55

Korail

• Korail Class 341000 (ex-Korail Class 2030)
  • 1st generation: 341-01~341-25
  • 2nd generation: 341-26~341-30
  • 3rd generation: 341-31~341-37
  • 4th generation: 341-38~341-55
    • Trains 341-53~341-55 are temporary running on Line 1.

• 
  Seoul Metro 4000 series EMU (2nd generation)
• 
  Korail Class 341000 (1st generation)
• 
  Korail Class 341000 (2nd generation)
• 
  Korail Class 341000 (3rd generation)

Former

Seoul Metro

• Seoul Metro 3000 series (former 4000 series)
  • Wide-width GEC Traction chopper resistor controlled electric car (1985–1993; transferred to Seoul Subway Line 3)

Korail

• Korail Class 1000 (Ansan Line only, transferred to Seoul Subway Line 1)

• 
  Seoul Metro (former) 4000 series GEC stabled at Changdong Depot
• 
  Seoul Metro 3000 series GEC (Former 4000 series GEC), June 2013
• 
  Korail Class 1000 (2nd batch)