Seoul Subway Line 2

Seoul Subway Line 2 (서울 지하철 2호선), also known as the Circle Line, is a circular line of the Seoul Metropolitan Subway. The line running clockwise is called the "inner circle line" and the counter-clockwise line is called the "outer circle line". This is Seoul's most heavily used line, and consists of the main loop (48.8 km), the Seongsu Branch (5.4 km) and the Sinjeong Branch (6.0 km) for a total line length of 60.2 km. The Line 2 loop is the third longest subway loop in the world after Moscow Metro Bolshaya Koltsevaya line and Beijing Subway Line 10. In 2019, Line 2 had an annual ridership of 812 million passengers or 2.2 million passengers per day.

Headways on the line vary from 2 minutes 18 seconds on peak periods and 5–6 minutes off-peak periods. The line connects the city centre to Gangnam, Teheran Valley and the COEX/KWTC complex.

History
In 1972, then-Mayor of Seoul 구자춘 (1932–1996) changed the existing plans for the Seoul Subway to better enable connectivity around the growing Seoul City and allow for development to take place across the Seoul Capital Area. Line 2 was built in 1978–84 together with the Seongsu Branch (the second Sinjeong Branch was built 1989–95). Dangsan bridge was closed for reconstruction in 1996 and reopened November 22, 1999. The old steel girder bridge was replaced by a 1.3 km long concrete bridge between Dangsan on the southern side of the river and Hapjeong on the northern bank.

Yongdu station on the Seongsu Branch (between Sindap and Sinseol stations) is the first station in the Seoul Subway system with operating platform screen doors. As of 2008 platform screen doors are operating at all stations along Line 2. New rolling stock has also progressively came on line, replacing older vehicles.


 * October 31, 1980: Sinseol-dong – Sports Complex (via Seongsu) section opened
 * December 23, 1982: Sports Complex – Seoul Nat'l Univ. of Education section opened
 * September 16, 1983: Euljiro 1-ga – Seongsu section opened; Sinseol-dong – Seongsu section separated as Seongsu Branch
 * December 17, 1983: Seoul Nat'l Univ. of Education – Seoul Nat'l University section opened
 * May 22, 1984: Seoul Nat'l University – Euljiro 1-ga (via Sindorim) section opened; the Circle Line (the longest in the world at 54.2 km until it was surpassed in 2013) is completed.
 * May 22, 1992: Sindorim – Yangcheon-gu Office section opened as Sinjeong Branch
 * February 29, 1996: Sinjeongnegeori Station opened as extension of Sinjeong Branch
 * March 20, 1996: Kkachisan Station opened as extension of Sinjeong Branch
 * October 20, 2005: Yongdu Station opened on the Seongsu Branch
 * September 2010: Siemens Mobility ATP/ATO GoA 2 signalling system implemented on newer trains to increase frequencies and route capacity.

Facilities
In December 2010 the line is recorded as having the highest WiFi data consumption in the Seoul Metropolitan area. It averaged 2.56 times more than the other 14 subway lines fitted with WiFi service zones.

In 2011, retailer Homeplus opened the world's first virtual supermarket at Seolleung station, where smartphone users can photograph the bar code of life-size pictures, on the walls and platform screen doors, of 500 items of food, toiletries, electronics etc., for delivery within the same day.

Stations
All stations on all branches are in Seoul.

Extension
There is a possible extension currently in the conception stage to extend the Sinjeong Branch to 3.7 km to Gayang Station on Line 9. The path would include a new station named Gangseo-gu Office in between Kkachisan and Gayang.

Rolling stock
Five generations of Seoul Metro 2000 series trains have been used on Seoul Subway Line 2. As of July 2024, only third, fourth and fifth batch 2000 series trains are in operation (manufactured by Hyundai Rotem and Dawonsys respectively), since all first (MELCO thyristor chopper control) and second batch (GEC Traction/Alstom thyristor chopper control) trains have been retired between 2008 and 2023. All trains are stored and maintained at Sindap Depot on the Seongsu Branch and Sinjeong Depot on the Sinjeong Branch.