Henry Ernest Dudeney/Modern Puzzles/48 - Railway Shunting

by : $48$

 * Railway Shunting
 * How are the trains in our illustration to pass one another, and proceed with their engines in front?


 * [[File:Dudeney-Modern-Puzzles-48-question.png]]


 * The small side track is large enough to hold one engine or one carriage at a time, and no tricks, such as ropes and flying-switches, are allowed.


 * Every reversal -- that is, change of direction -- of an engine is counted as a move in the solution.


 * What is the smallest number of moves necessary?