25 March 2014

Puzzle: Railway Track

This is one of those “shunting” puzzles. As you can see in my somewhat clumsy diagram, there is a railway track that goes indefinitely to the right. On the left, it splits into a “Y”, both ends of which merge into a finite straight railway track. There is a coach “A” sitting on one arm of the Y and another coach “B” sitting on the other arm. Both the coaches are 5 yards each.

The distance between the junction point on coach A side and the end of the finite straight track is 5 yards. On the other side, near coach B, the distance between the junction point and the end of the straight finite track is 15 yards. (See pic). In between the junction points on the straight track sits an engine “E” which is itself 10 yards in length.

Like every engine, E can go forwards or backwards and can pull or push the coaches. Any coach and engine can be attached to each other.

Here is the puzzle: Can you interchange the position of coach A and coach B? You have to get engine E back to its original position when you are done.


Posted March 25, 2014 by Rajib Roy in category "Puzzles


  1. By Captain Bakul Joshi on

    I had solved it in year 2008 exactly the same way you have presented.
    I use this for team building activities now and believe me 90% meriters fail to even design answers’ stages. They don’t even think that they can simply stage the picture and step the movement of each situation.
    Miraculously, streetsmart below average or average attendees always end up cracking this in about 15 minute.
    So glad to see this.

    1. By Rajib Roy (Post author) on

      Captain Joshi,
      Indeed we have started understanding our cognitive functions enough to realize that what we call “intelligence” – often measured by IQ is not what drives judgment or wisdom. There are two other factors. If you ever get a chance, read a book “The Intelligence Trap” which does a great job in explaining this. There is a related problem – “Duncker’s candle problem” – you can read it up on the internet. Most “intelligent” folks get stumped. People who score lower on IQ tests in general solve this problem faster.


Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.