The line runs 47 km (29 mi) south from Ilsan in Goyang City, crosses the Han River, passes Gimpo Airport, Sosa, Siheung, and ends in Wonsi in Ansan.

There is a transfer to different lines at Daegok, Neunggok, Gimpo Int'l Airport, Bucheon Stadium, Sosa and Choji.

The line is operated by Korail, but the stations between Sosa and Wonsi are managed by SEO HAE RAIL CO.,LTD., which is a subsidiary of Seoul Metro.

[2] The infrastructure is also owned by Korail so the line runs on the left like the rest of the South Korean mainline railway network.

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.

Another part of the tentative 2010 plans was a southern extension from Wonsi, connecting up with the Janghang Line before Hongseong station.