hard shoulder vs kerb

hard shoulder

noun
  • A verge to the side of a highway, which should be used only in case of an emergency (especially on a motorway) 

kerb

noun
  • The raised edge between the pavement and the roadway, typically made of concrete though originally consisting of a line of kerbstones. 

  • A stone ring built to enclose and sometimes revet the cairn or barrow built over a chamber tomb. 

verb
  • To damage vehicle wheels or tyres by running into or over a pavement kerb. 

  • To take a dog to the kerb for the purpose of evacuating. 

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