collar beam vs railroad tie

collar beam

noun
  • A horizontal piece of timber connecting and tying together two opposite rafters. 

railroad tie

noun
  • A heavy, preserved piece of hewn timber laid crossways to and supporting the rails of a railroad or a member of similar shape and function of another material such as concrete. 

  • A long, thin wooden beam used as a border in driveways, to hold in soil in gardens, etc. 

How often have the words collar beam and railroad tie occurred in a corpus of books? (source: Google Ngram Viewer )