Answer:
I come with a train and go with a train and the train doesn't need me but can't go without me.
I build bridges of silver and crowns of gold. What am I?
I make a loud noise when changing jacket. I become bigger and delicious.
What has 3 feet but no toes?
So simple, that I can only point. Yet I guide men all over the world.
It has no top or bottom, but it can hold flesh, bones, and blood all at the same time.