branch line

branch line (plural branch lines)

1. (rail transport) A secondary railroad route or one subsidiary to a railroad's mainlines.
   • 1987, William H. Rehnquist, The Supreme Court:

     But the states were generally concerned with the location of trunk lines and left it to cities and counties to worry about branch lines.

2. (rail transport) A non-through line which joins a mainline (or another branch or secondary line) and ends at a terminus.
   • 1962 December, “Dr. Beeching previews the plan for British Railways”, in Modern Railways, page 377:

     They saddled themselves with the handling of light flows on a multiplicity of branch lines, and they sacrificed the speed, reliability and low cost of through train operation, even over the main arteries of the system.

   • 2023 February 8, Christian Wolmar, “Pressing issues to help Eurostar fulfil its ambitions”, in RAIL, number 976, page 39:

     Above all, Eurostar needs to be proactive in improving the service, reducing fares, and getting back to a post-COVID normal, despite Brexit. Or is it that SNCF just feels London is on a branch line from the rest of Europe, and not worth bothering about?