Here's the beginning of a train ride at the zoo:
The thing about trains, is they're EXCITING. And that means they're tiring.... We quickly progress to the "snuggle and look at scenery" phase.
Once, before Jack fell asleep, he was allowed to go in the actual engine part while the driver took a break. Here's him almost releasing the brake:
And examining the fire box (I think). Notice how he really is in the train all by himself. He could have driven the thing away, if he had been lucky enough to find the right combination of levers!
According to his current plans, when he grows up he is going to drive trains and tractors. I believe it, too! :)