The Bundang Line or Seoul Metropolitan Subway Bundang Line (Sudogwon Jeoncheol Bundangseon 수도권 전철 분당선) was a commuter rail line of the Seoul Metropolitan Subway in the Seoul Capital Area operated by Korail.
Also it refers physical railway track from Wangsimni to Suwon which is designated by MOLIT.
The line service started in central eastern Seoul at Cheongnyangni, crossing Gangnam District and connecting the cities of Seongnam and Yongin, and terminates at Suwon Station.
Trains run at half the frequency between Jukjeon and Suwon, except during rush hours.
The negative sign is only a convention for distance notation from Wangsimni Station, the terminus of most services.