Yeah this is something I've been digging into for a while actually. Norfolk hasn't had many reported Dogman cases that I know of but when I started mapping out the ones from the Midlands and up into Yorkshire there's a pretty clear clustering along old rail corridors, particularly lines that were closed during the Beeching cuts in the 60s.
My working theory is it's less about the rails themselves and more about what those abandoned lines became - long uninterrupted wildlife corridors basically. Dense overgrowth, minimal human foot traffic, connects woodlands that would otherwise be fragmented. If something like this exists it would absolutely use those routes for movement.
There's also an interesting overlap with old droving roads and ley line maps but I don't want to go too deep down that rabbit hole without more data points.
Has anyone done any actual fieldwork along disused lines? I'd be really interested if anyone has GPS logged encounter locations because I think if we overlaid those properly on an OS map the pattern would be pretty undeniable.