  An inglenook puzzle is a classic shunting (switching) puzzle often found on
model railway layouts. A collection of wagons sits in a fan of sidings with a
limited length headshunt (lead track). The aim of the puzzle is to rearrange
the wagons into a desired order (often a randomly chosen order). This article
answers the question: When can you be sure this can always be done? The problem
of finding a solution in a minimum number of moves is also addressed.
