rapid transit system
From Longman Dictionary of Contemporary EnglishRelated topics: Trains & railwaysrapid transit systemˌrapid ˈtransit ˌsystem (also rapid transit) noun [countable] American English TTTa system for moving people quickly around a city using trainsExamples from the Corpusrapid transit system• He was the chief architect in charge of the then-burgeoning rapid transit system - and it turns out he was also a painter.