high road vs trunk road

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. 

trunk road

noun
  • An important main road used by long-distance traffic, as well as heavy lorries. 

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