Collocations for rail - noun

guard, safety
curtain, picture, towel (all esp. BrE)
heated towel rails

altar, balcony, banister, porch (esp. AmE), stair
bottom, top
She climbed onto the top fence rail.

steel, wooden, etc.

grab, grasp, grip, hold on to, lean on
She held tightly on to the rail.

hang from
Lace curtains hung from the brass rails over the bed.

fit, fix

on a/the rail
She sat on the rail.

over a/the rail
He folded the towel over the rail.

run along rails, run on rails
Trams run along rails.

along (the) rails
The train thundered along the rails.

between the rail
Weeds grew between the rails.

on (the) rails
The gun is mounted on rails.

come off the rails, go off the rails
The train came off the rails.
She was worried her son was going to go completely off the rails. (figurative)

ride the rails (= travel around by train)

high-speed, light
Many business people now opt for high-speed rail rather than flying.

commuter, freight, passenger (all esp. AmE)
He uses a combination of commuter rail and subway to get to work.

fare, ticket (both esp. BrE)
network, system
efforts to modernize the rail network

route
timetable (esp. BrE)
service
connection, link
the Channel Tunnel rail link

line, track
journey (esp. BrE), trip
station, terminal
car (esp. AmE)
commuter, passenger, traveller/traveler, user (all esp. BrE)
transit (AmE), transport (esp. BrE), transportation (esp. AmE), travel
traffic
freight
bridge
accident, crash, disaster (all esp. BrE)
staff (BrE), worker
union (BrE)
enthusiast (BrE)

by rail
We went from Paris to Budapest by rail.