back road vs roadway

back road

noun
  • A secondary road, a little-used road, a road through rural areas sometimes used as an alternative to main roads. 

roadway

noun
  • A way used as a road. 

  • The main or central portion of a road, used by the vehicles. 

  • The portion of a bridge or railway used by traffic. 

How often have the words back road and roadway occurred in a corpus of books? (source: Google Ngram Viewer )