commuter rail vs itinerant

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 

itinerant

noun
  • One who travels from place to place. 

  • A member of the Travelling Community, whether settled or not. 

adj
  • Habitually travelling from place to place. 

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