noun
Refers to a railway line or road that diverges from a main route. Common in transportation contexts.
この分岐線は本線から駅へ続いている。
This branch line runs from the main line to the station.
新しい分岐線が工業団地まで敷設された。
A new spur was laid to the industrial park.
支線 is a more general term for a branch line, while 分岐線 emphasizes the point of divergence.
Compound of 分岐 (branching) and 線 (line). The exact historical derivation is uncertain, but the term is transparently formed from its components.