railway line

Short definition from Wiktionary

Noun

1. 1
   A railway track; a pair of rails on which a railway train runs.
2. 2
   A group of railway tracks running parallel, allowing one track to be used for each direction (a double-track railway line), or allowing segregation of fast trains from stopping trains (a four-track railway line).
3. 3
   An organization that runs a railroad.