ido ▁to ▁Song do . ▁▁ 2 0 1 4 : ▁December ▁ 2 7 : ▁Dar wol ▁Station ▁opens ▁as ▁an ▁in - fill ▁station . ▁▁ 2 0 1 6 : ▁February ▁ 2 7 : ▁The ▁line ▁is ▁extended ▁west ward ▁from ▁Song do ▁to ▁In che on . ▁▁ 2 0 1 7 : ▁July ▁ 1 0 : ▁Express ▁service ▁is ▁launched ▁on ▁the ▁line . ▁ ▁Future ▁Pl ans ▁H ag ik ▁station ▁is ▁planned ▁to ▁open ▁between ▁Song do ▁and ▁In ha ▁University ▁in ▁ 2 0 2 0 . ▁Ph ase ▁ 3 ▁of ▁the ▁Su in ▁Line , ▁which ▁will ▁extend ▁the ▁line ▁east ▁from ▁O ido ▁to ▁Su won , ▁will ▁allow ▁for ▁a ▁through ▁service ▁through ▁the ▁Bund ang ▁Line . ▁This ▁will ▁create ▁a ▁long ▁line ▁from ▁Che ong ny ang ni ▁Station ▁to ▁In che on ▁Station ▁( t ent atively ▁the ▁" B und ang - Su in " ▁Line ). ▁In ▁addition , ▁a ▁connection ▁line ▁is ▁under ▁consideration ▁at ▁Su won ▁that ▁will ▁allow ▁K TX ▁trains ▁to ▁run ▁between ▁the ▁G ye ong bu ▁high - speed ▁railway ▁and ▁In che on ▁Station ▁via ▁the ▁Su in ▁Line ▁by ▁ 2 0 2 5 . ▁ ▁St ations ▁ ▁Current ▁alignment ▁ ▁Form er ▁alignment ▁ ▁Rol ling ▁stock ▁For ▁the ▁current ▁Su in ▁Line , ▁Kor ail ▁introduced ▁third ▁generation ▁Class ▁ 3 5 1 0 0 0 ▁EM U ▁trains . ▁They ▁are ▁the