Hello; This reminds me of the flight from Los Angeles to Baltimore, sitting in the window seat above the exhaust end of the engines, watching dozens of rivets loose in the wing's sheet metal panels. They constantly vibrate, wearing away the holes. It would take a pretty large linear gap in the RR track (along wheel's path of travel) to cause a serious problem, but a lateral gap, such as a skewed rail. This also shows the tremendous forces at work every time any train runs over any track. Train tracks definitely really take a pounding wherever they are. So I know this is old now but still awesome. I cant believe though it took me several years to realize how dangerously close you were to a bad joint each time. I'm left with a realization that whether it gives out or not its the next track end downrange that might cause a derailment right next to ya. At least with a simple quick physics crunch. Although it is obviously very desirable that the track be maintained and repaired, it does show how (at low speeds) trains can manage on very rough track which is why they can be useful in emergency situations and have worked well on battle fronts.