high road vs superhighway

high road

noun
  • A main road or highway. 

  • Used other than figuratively or idiomatically: see high, road. 

  • A course of action which is dignified, honourable, or respectable. 

superhighway

noun
  • An expressway, especially one designed for high speeds. 

  • The primary mechanism used in the movement of electronic data or information; information superhighway. 

  • A major route that carries most of the traffic going in a given direction by a specified mode of transportation. 

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