Seoul Proposed Metro Lines — Planned Subway Routes and Future Underground Expansions

Seoul planned and proposed metro lines. Future underground routes and rapid transit expansion projects before construction begins.

Seoul metro and subway lines formally proposed or in active planning: future underground corridors announced, studied or included in urban transport master plans but not yet under construction. Shows where cities plan to extend rapid transit coverage — new orbital lines connecting suburbs without routing through the city centre, extensions to areas beyond the existing network and entirely new metro systems in cities currently without subway.

Seoul has 4 proposed railway segments including 4 metro.