I was on Amtrak a few years back and we made an unscheduled stop out in the middle of nowhere. A few minutes later, one of the conductors got on the intercom to

I was on Amtrak a few years back and we made an unscheduled stop out in the middle of nowhere. A few minutes later, one of the conductors got on the intercom to let us know that the train had run over a shopping cart, and that they were going to have to dig the mangled remains out from underneath the engine. I went back to my game and we were under way soon enough, but can you imagine if an engineer had to drive out to meet the train and put it back into operation? We would have waited hours just for them to drive hundreds of miles out to where the train was. I imagine it's less of a problem on a little subway system.