(related to Problem: The Tube Inspector's Puzzle)
The inspector need only travel nineteen miles if he starts at $B$ and takes the following route: $B A D$ $G D E$ $F I F$ $C B E$ $H K L$ $I H G$ $J K.$ Thus the only portions of line travelled over twice are the two sections $D$ to $G$ and $F$ to $I.$ Of course, the route may be varied, but it cannot be shortened.
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