back road vs tortuous

back road

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

tortuous

adj
  • Twisted; having many turns; convoluted. 

  • Oblique; applied to the six signs of the zodiac (from Capricorn to Gemini) that ascend most rapidly and obliquely. 

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