Richard McClintock

I read this book when I was a kid, not all that long after it was published. I have never forgotten it - one of my favorite books ever. Not only is it about trains, which alone would have recommended it to me, but it is about boys my own age who (unlike today's sheltered youth) are allowed to wander freely around the mountainsides. They discover a Nazi plot (apparently a true thing) to blow up the railroad they love - and manage to foil it, despite being captured by the bad guys and left without clothes in the freezing woods.