I played in, on and around freight trains when I was a kid, there were tracks about a quarter mile behind our house, the trains stopped there for a few hours a lot, we had to cross those tracks to get to the grocery store and when there was a train stopped there we would go under the train to cross the tracks.
When the trains left we would hop on and ride a mile or two 'til they got going too fast.
When they went by at speed we would toss the rocks that line the tracks under the wheels and watch them pulverize in an instant.
good times, good times