It's not just the kids you have to worry about. A couple of years ago my friend had a large party and a bunch of us went to the cellar to see his layout. The kids in the group behaved, but a couple of adults (perhaps fueled by a few beers) thought it would be fun to see how fast the trains would go. I had to grab the throttle to slow the trains and politely remind them that a high speed derailment could cause a lot of damage to our friend's trains.
John