Background
Cheltenham used to have a network of railways but this has been reduced to one line. If one searches hard, traces of these old lines can be found and the routes they used to take can be worked out. The cache is not at the posted coordinates; the posted coordinates are where the Hatherley Loop joined the mainline. From the archived Hatherley Loop geocache:
'Hatherley loop' used to be the link between the Great Western Railway and the Midland and South Western Junction Railway. The GWR is still in operation, but the M&SWJR was taken up long ago.
The cache
Test your detective skills by working out the route a railway line takes through the grid below (known as a Train Tracks puzzle).
Complete the track from the top-left to the bottom-right so that the rows and columns contain the same number of track segments as are indicated in the clues to the left and bottom of the grid. There are only straight and 90-degree curved rail sections, and the track may not cross itself. A few sections have been added to help and the track does not pass through the black square.
Once you've solved the train track then read out the six four-digit binary numbers from the rectangles with a grey background. Where there is track in the square then that's a 1, if there's no track that's a 0. Convert to decimal. Read down the first column of numbers to get the final three digits of the northing (XXX). Read down the second column of numbers to get the final three digits of the easting (YYY). The cache is to be found at N 51 53.XXX and W 2 07.YYY.
