commuter rail vs tramcar

commuter rail

noun
  • A rail transport system with trains used to transport commuters between two places, typically their homes and works, normally within a metropolitan area and its surrounding environs, and generally distinguished from other rail transport systems (i.e. subways, metros, tramways) by having less frequent service, lacking free transfers between trains and using heavy rolling stock running on a mainline railway 

tramcar

noun
  • A rail vehicle for carrying loads in a mine; a tram. 

  • A streetcar. 

How often have the words commuter rail and tramcar occurred in a corpus of books? (source: Google Ngram Viewer )