bump in the road vs impediment

bump in the road

noun
  • A setback or obstacle, especially one which is relatively minor. 

  • A very small town. 

impediment

noun
  • A hindrance; that which impedes or obstructs progress. 

  • Baggage, especially that of an army; impedimenta. 

  • A disability, especially one affecting the hearing or speech. 

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