roadsweeper vs scavenger

roadsweeper

noun
  • A person employed to sweep streets 

  • A machine used to sweep streets 

scavenger

noun
  • Someone who scavenges, especially one who searches through rubbish for food or useful things. 

  • A child employed to pick up loose cotton from the floor in a cotton mill. 

  • An animal that feeds on decaying matter such as carrion. 

  • A substance used to remove impurities from the air or from a solution. 

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