The chances of finding a MW capable mini radio that’ll get a signal on a train for that long are pretty remote. Even FM will suck like a Dyson on a phone; I can actually see my local transmitter from where I live, but it’s almost impossible to get a signal on my old N95 at the back of the house. Even my car radio loses the signal three miles away. It’s output is 2W, I kid you not, because all the old analogue transmitters are being wound down for Digital. Get a DAB.