roadway vs stepping stone

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. 

stepping stone

noun
  • Something used as a way to progress to something or somewhere else. 

  • A stone that can be stepped on in crossing something, especially a marsh or creek. 

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