roadway vs superhighway

roadway

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

  • A way used as a road. 

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

superhighway

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

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

  • An expressway, especially one designed for high speeds. 

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