(rail transport) A railway that is or was owned and operated by more than one company.
1959 April, “Motive Power Miscellany: London Midland Region”, inTrains Illustrated, page221:
The engine was No. 60920, which was seen passing southbound through Preston and then at about 1.0 p.m. heading its train over the formerjoint line fromWarrington viaHelsby to theChester district; [...]