Interesting thread this. I don't follow Dogman cases as closely as I do Bigfoot but I have noticed the railroad corridor thing coming up repeatedly in reports from the States. Old rail lines often cut through dense woodland and follow river valleys which are exactly the kind of habitats you'd expect any large cryptid to use as a travel corridor.
My thinking is that its less about the rail lines themselves and more about what surrounds them. Abandoned infrastructure, overgrown embankments, minimal human foot traffic. Could be coincidence obviously but when a pattern shows up across multiple independent reports from different states you have to at least take it seriously.
Anyone got UK equivalents? We've got old disused rail lines all over the place, some running through pretty remote stretches. Never seen anything myself but would be curious whether there are any British Dogman type reports near them.