Namtaeryeong Station is a station on the Seoul Subway Line 4. It is the southernmost station on Line 4 that is operated by Seoul Metro. The name of this station literally means "great southern pass," referring to a passageway linking Seoul and Gwacheon, between Mt. Gwanak and Mt. Umyeon. Most of the provincial railways in South Korea were built with Japanese expertise when Korea was under Japanese rule. The left-hand track is still used for trains. But the Seoul Metro, which was constructed much later in the 1970s, used the right-hand track for its subway lines, including Line 4. Therefore, between Namtaeryeong and Seonbawi Stations, where the two lines connect, the underground tracks must cross over from left-to-right and right-to-left.