bollard vs safety island

bollard

noun
  • A similar post preventing vehicle access to a pedestrian area, to delineate traffic lanes, or used for security purposes. 

  • A strong vertical post of timber or iron, fixed to the ground and/or on the deck of a ship, to which the ship's mooring lines etc are secured. 

safety island

noun
  • An area of roadway from which traffic is excluded so as to provide safety for pedestrians; a traffic island. 

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