Not really my area - I'm more of an earth mysteries person - but this caught my eye because Dartmoor has some old mineral railway lines, mostly abandoned Victorian-era tramways used for the granite quarries. Never seen anything doglike out there myself, but I have noticed the old trackbeds seem to attract something. Strange lights, odd feelings, that sort of thing.
The railway corridor idea is interesting though. Makes me wonder if there's something to the ley line angle - old routes, whether Roman roads, drovers' paths, or railways, often follow much older alignments. Could be the dogman reports are clustering along these corridors for similar reasons that other phenomena do.
A few questions for those with more experience in this area:
Are the sightings happening on the tracks or in woodland alongside them?, Is there a pattern with time of year?, Has anyone cross-referenced with older Native American trail routes in the US cases?
I've been reading through some of the BORU research archives online and a surprising number of accounts do mention linear features - roads, rivers, railways. Might be worth someone doing a proper map overlay if it hasn't been done already. I wouldn't know where to start with that sort of thing myself, but it seems like the kind of project that could actually produce something concrete rather than just anecdote.
Curious what others have found.