Seoul Subway Line 8 of the Seoul Metropolitan Subway was built from 1990 to 1999 and mainly serves the southeastern parts of Seoul and Seongnam. The first section from Jamsil to Moran opened in 1996, and the second section from Moran to Amsa was opened in July 1999. The line color is rose. In 2019, Line 8 had an annual ridership of 112 million or about 307,000 people per day. At 17.7 km (11.0 mi) in length, Line 8 is the shortest of all heavy rail Seoul Metropolitan Subway lines.

Seongnam is the fourth largest city in South Korea's Gyeonggi Province after Suwon and the 10th largest city in the country. Its population is approximately one million. Seongnam is a satellite city of Seoul. It is largely a residential city located immediately southeast of Seoul and belongs to the Seoul Capital Area.