NYC 's 'local' vocabulary includes the terms: IRT, IND, and BMT these initals are the 'names' of the long defunct companies that once owned various parts of the NYC transit system. (originally there were three private, competing companies.. but NYC has owned all three since before WWII)
there is almost no remnant of reference to them in the subway system, but many NYers still use them to define subway lines.. some out of towners/transplanted NYers even know for were they originated. tourist name lines by the colors used on new subway maps.. ('is this were i can catch the RED line?--(Sure, the IRT No1 stops over on that platform.)
all three lines are different.. (NYC has 3, count'em, 3 sets of rolling stock for the subways (and don't even mention the new 'Monorail to JFK-an other set of rolling stock!)) so you can 'learn the lines' by just looking at the subway cars. (IRT, cars are short (not as much headroom), wide and long) IND cars are High (great for basketball players)medium and narrow. BMT cars are the worst.. low, short and narrow.)
