
...a hot dog stand
in a converted RAILROAD dining car.
The Big Bang Theory Season 4, Episode 6

In 1944, the Pacific Railroad
built number 6131,
The Big Bang Theory Season 7, Episode 15

down by the RAILROAD tracks."
Breaking Bad Season 2, Episode 12

Well, Sheldon was going on and on
about time zones and RAILROAD schedules,
The Big Bang Theory Season 9, Episode 16

There are dozens of RAILROAD crossings
you have to blow the whistle for.
The Big Bang Theory Season 10, Episode 15