I didn't grow up near railroad tracks, so most of these activities are as new to me as they are to my granddaughters. I've often stood on the other side of my fence and watched trains pass, so close you could feel the ground shake; but that was the extent of it.
Cliff has told stories about how he'd put pennies on the track when he was a child, to smash them. He said he must have really been young, because he remembers worrying that the coins might de-rail the train.
I believe my children went back to the track to smash pennies, too, years ago; I don't recall whether they had any success with the enterprise.
Anyway, this sounded like something Monica and Natalie would enjoy, so off we went. I took Scotch tape along, thinking the pennies would vibrate off the rail before the train reached them. Of course I knew the tape wouldn't last, but at least the train would make contact with our pennies this way.
Altogether, it took about ten pennies and two trains to give us three flattened pennies. So now we each have a keepsake.
Oh, and the engineer of the second train that passed scooted over to our side and waved out the window at us! You can imagine our glee at that. There was much screaming and laughing.
I'm glad I haven't grown up yet. It's fun being a kid.