Plank puzzle span diagram
This is a span diagram for the Route-66 plank puzzle, courtesy of Graham's solver (one of the key stages of solving a plank puzzle is to work out all valid placements for all planks, referred to as plank spans). Note there are a total of 54 (hexadecimal 36) distinct spans in this puzzle, yet the solution is 66 moves (so you just know you are going to have to walk some of those spans several times!). Infact Route-66 is the only puzzle so far where the number of moves actually exceeds the number of plank spans.
fig.1: span diagram for Route-66