title: How to check if 2 routes share a path
body: <p>I have 2 routes, routes <code>A to B</code> and <code>C to D</code> on google maps. Now route <code>C to D</code> share the same street/path with route <code>A to B</code>. How do I check if one is on the polyline of the other?</p>
  
  <p>For example: <a href="http://i.stack.imgur.com/XvieC.png" rel="nofollow">C to D is on A to B</a></p>