The railway track or service direction for trains traveling away from a major city (outbound); known as the 'down' line (antonym: 'up' line).
朝の下り線は通勤客で非常に混んでいる。
The morning down line is very crowded with commuters.
事故のため下り線が一時運休になった。
The down line was temporarily suspended due to an accident.
次の駅は下り線ホームの方がわかりやすい表示になっている。
At the next station, the signage on the down line platform is easier to understand.