Answer:

rails

Answer	Crossword Clue
RAILS	Marsh birds
RAILS	Train tracks
RAILS	Crossties support them

RAILS	Pieces of ironwork
RAILS	Train need
RAILS	Portcullis parts
RAILS	Local supporters?
RAILS	Some racehorses hug them
RAILS	Racetrack borders
RAILS	Banisters
RAILS	Stock category

RAILS	Denounces, with "at"
RAILS	Some transportation stocks
RAILS	Hobos may ride them
RAILS	Track borders
RAILS	Vagabonds might ride them
RAILS	Roller coaster guides
RAILS	Wading birds
RAILS	Racetrack boundaries

RAILS	Small wading birds
RAILS	Racetrack fences
RAILS	Train lines?
RAILS	Engineer's path
RAILS	Streetcar tracks
RAILS	Abe famously split them
RAILS	"Split" fence parts
RAILS	Bars under bar cars

RAILS	Pool table cushions, informally
RAILS	Complains vehemently
RAILS	Tracks
RAILS	Inveighs against
RAILS	Subway lines?
RAILS	Train set set
RAILS	Track boundaries
RAILS	Train support

RAILS	Fence pieces
RAILS	Complains about, with "against"
RAILS	Roller-coaster supporters
RAILS	Roller-coaster parts
RAILS	Stairway banisters