Never really looked into Dogman before but this thread caught my eye because I spend a lot of time out near the old railway cuttings around Rendlesham and the surrounding Suffolk area doing ghost work, and there's definitely something about those old corridors that seems to attract weirdness in general.
I've read a bit about ley lines and how ancient tracks - both physical and metaphysical - tend to follow similar routes. Old rail lines often followed even older paths, drovers roads, Roman roads, that sort of thing. So maybe whatever is being seen near railways isn't responding to the railways themselves but to something much older running underneath them.
Not saying I've seen a Dogman personally but I've had some experiences out that way at night that I couldn't easily explain, shapes moving wrong, sounds that didn't fit any animal I know.
Would be really interested to hear from anyone who's mapped their sighting locations against old OS maps to check what was there before the railways came through. Has anyone actually done that kind of overlay work or is it mostly anecdotal at this stage?