#rail_line__line__railway_line__railwayline  railroad track and roadbed
  supertype:  railroad_track__railroad__railway  a line of track providing a runway for wheels; "he walked along the railroad track"
  subtype:  branch_line  trunk_route
  part:  railroad_bed  a bed on which railroad track is laid
  part:  railroad_track__railroad__railway  a line of track providing a runway for wheels; "he walked along the railroad track"
     part:  railroad_tie__tie__crosstie__sleeper  one of the cross braces that support the rails on a railway track; "the British call a railroad tie a sleeper"
     part:  rails__rail__track  a bar or bars of rolled steel making a track along which vehicles can roll

No statement uses or specializes rail_line; click here to add one.