3 yr old only wants to watch trains. anywhere near vanasthalipuram to see them up close?

he's moved on from diggers to trains. same train videos on loop. i'd much rather take him to see a real one on the weekend than give him another hour of youtube. is there a spot on this side of the city where trains pass and it's safe to stand with a small kid? would rather avoid platform tickets at a big station, but will do it if that's the answer