noun
bus route; service route
Refers to a specific numbered or named bus route in a transit system, often used in schedules and announcements.
このバス停には運転系統が3つ通っています。
Three bus routes serve this bus stop.
路線 is a general term for any transportation line (bus, train, etc.), while 運転系統 specifically refers to a bus route within a transit network.
Compound of 運転 (operation, driving) and 系統 (system, lineage). The exact historical derivation is uncertain; the term is conventionally used in bus transit contexts.