Seoul metropolitan subway is one of the most widely used rapid railway transport system in the world. Credit: testing / Shutterstock.
Interior of one of Seoul Metropolitan Subway trains. Credit: ST_Travel / Shutterstock.
Pictured here is the Hapjeong Station on Line 2. Credit: Yeongsik Im / Shutterstock.
Ticket vending and card reload device at one of the stations. Credit: cherry-hai / Shutterstock.
The Seoul metropolitan subway system serves nearly ten million inhabitants of Seoul and the provinces of Gyeonggi, Incheon and northern Chungnam. Credit: Carlos Huang / Shutterstock.

Seoul metropolitan subway in South Korea is the most widely used rapid railway transport system in the world, featuring ten subway lines. The system serves nearly ten million inhabitants of the capital city, Seoul, and the provinces of Gyeonggi, Incheon and northern Chungnam. The total length of the subway line is approximately 327.1km, including  290km underground. The subway has 302 stations, serving millions of passengers every day.

The lines are operated by four companies – Seoul Metropolitan Subway (Seoul Metro), Seoul Metropolitan Rapid Transit (SMRT), Korail (Korea National Railroad) and Metro 9. Line 1 operations were initiated by Korail in 1974. The company’s operations later expanded to lines 2, 3 and 4. SMRT was formed in 1994 and operates lines 5, 6, 7 and 8.

A new 25.5km section of the subway, line 9, was opened in 2009 to connect Gimpo Airport with Sinnonhyeon in south-east Seoul. It serves 38 stations.

Seoul subway line 9 project

Seoul subway line 9, which runs east along the south bank of the Han River, was planned to open in three phases. The line connects Gimpo Airport with line 5 and with AREX, a private railway line.

The section has three tracks carrying express trains in both directions and passing through nine stations. The line also has six transfer stations for lines 1, 2, 3, 4, 5 and 7. It runsfour-car Hyundai-Rotem trains at speeds of 33km/h for local-stopping trains and 47km/h for express trains, allowing passengers to reach Gimpo from Gangnam in under 30 minutes.

The second section of the subway line 9 that connects the Olympic Stadium station with Sinnonhyeon was completed in 2015. The third section connecting the stadium to Bangi-dong was opened in 2018.

Subway lines are colour coded for easy identification. The colour coding system along with signs, written in both Korean and English, helps passengers to identify the lines and guides them the lines in appropriate direction.

Transfer points and upcoming stations are announced through pre-recorded voices in Korean and English.

Operation and funding

The project has been awarded to a consortium led by the railway system provider Hyundai Rotem. Veolia Transport Korea, through its operation and maintenance company Seoul Metro 9, will operate line 9 for ten years. Veolia Transport has an 80% stake in Seoul Metro 9, while the remainder is held by Rotem.

The subway is being funded by the Macquarie Korea Infrastructure Fund (MKIF). It is the first private investment in the subway system. The company has made investments in the form of equity and subordinated loans. MKIF has a concession term of 30 years, starting from July 2009. An investment of KRW74.4bn is expected to be invested in line 9.

Seoul Metropolitan Subway lines

Seoul metropolitan subway line 1 was built during 1971-74 and opened to public on 15 August 1974. Line 1 connects larger parts of the Seoul National Capital Area. It runs through the central regions of Seoul city, Incheon station in the south-west, Soyosan Station in the north-east and Sinchang station in the south. Train service is frequently available between Guro, Yongsan, Seoul, Cheongnyangni, Uijeongbu, Dongducheon and Soyosan. The trains have split stations between Byeongjeom and Cheonan in the south and Incheon in the west.

Line 2 was built between 1978 and 1984. It is the longest circular subway line in the world measuring 60.2km. It is also the most heavily used subway line in Seoul. Line 2 connects the central parts of Seoul city. Yongdu Station, which opened on 20 October 2005, was the first station of the Seoul subway system to have operating platform screen doors.

Line 3 was built between 1980 and 1993. The line connects south-eastern Seoul, Gangnam and the north-western end of Seoul to the city centre. Ilsan line and line 3 operate as one combined line.

Line 4 was completed in 1994. The long line connects the north-east to the south-west areas through the old city centre, the Seoul National Capital Area. The line divides into the Ansan and Gwacheon Lines.

Line 5 is the only subway line in Seoul to cross under the Han River and is an important east-west link. The line connects Gimpo International Airport, the Youido business area, downtown Seoul and the Gangdong residential districts. It was constructed between 1990 and 1996 and is the longest fully underground subway line measuring 52.4km.

Line 6 is a u-shaped subway line that passes through northern Seoul. A 4km section of line 6 was opened on 7 August 2000. Another 27km service was started on 15 December 2000. The line measures 35.1km and is represented in ‘brown’. Parts of line 6 are one-directional.

The 46.9 km Line 7 is a north-south line that connects Gangnam directly with northern parts of Seoul without touching the city centre. The line was built between 1990 and 1996 and began operations in 2000.

Line 8 connects the south-eastern parts of Seoul with the satellite city of Songnam. The 17.7km line was completed in 1999.

Bundang Line runs from south-eastern Seoul through northern Seongnam and extends to northern end of Yongin. It is operated by Korail and was opened in September 1994.

Jungang Line is also operated by Korail. The line connects Cheongnyangni with Gyeongju in eastern Seoul. Another line operated by Korail is Gyeongui Line and was opened in 1906. The line became part of the Seoul subway on 1 July 2009.


Seoul Subway deployed reusable RFID single-journey ticketing technology on 8 July 2009. Paper tickets are being replaced by RFID smart cards called single journey tickets. The RFID cards containing ST’s SRT512 contactless memory chip technology can be reused. Reusing tickets will save costs and will be environmentally friendly.

Seoul metro future

The Suseo and Garak Market line 8 is to be extended by 3km to connect to Ogeum of Line 5 by 2010.

Line 6 will be extended to the east to connect to the Gyeongchun Line enabling transfers, while line 7 will be extended to connect to Incheon subway on line 1 by 2010. The 9.8km extension with nine stations is aimed to relieve traffic congestion in northern Incheon and western Seoul. Line 8 will extend to the north of the Han River to Guri station.

Contractors involved

In June 2020, Thales received a contract from railway signalling company DaeaTi to supply new signalling equipment to support the capacity expansion of the Incheon Line 2 depot.

Thales was contracted by train contractor Woojin Ind in 2019 to provide Vehicle On Board Controller (VOBC) for the new driverless trains. in 2021, which in 2019 was contracted separately with train contractor Woojin Ind.