road map vs time line

road map

noun
  • A map with a visual representation of roads used for automobile travel and navigation. A road map may contain other relevant data, such as terrain or railway lines. 

  • A structured representation of objects to display a development plan. Road maps are used in business for strategic planning and communications. 

  • A plan of action, laying out the future actions of participants. 

time line

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