I’ve googled it but just can’t seem to grasp it. How do they stay on as well as they do at such high speeds, with so few incidents of crashing or derailing? Especially when anything could be lying across the track waiting to get lodged in the wheels.
I hear so often that trains are so safe, but I don’t think I can get over my anxiety with them until I understand *why* they’re safe.
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They are extremely heavy. And the wheel rims are flanged to prevent them from slipping out/off the rails, but the parts that rest on the rails are also conical which keeps the train centered between the two rails ([and is also the reason why they can go around curves without having differentials on their axels](https://www.youtube.com/watch?v=y7h4OtFDnYE)).
So basically to derail a train you have to put something across the tracks that the weight of the train/its very hard steel wheels can’t cut through, that will retain enough of its shape when the weight of the engine comes across it – basically need a giant chunk of metal or maybe concrete that is capable of lifting the weight of the engine up and off the rails.. or large enough that its mass and inertia is equal to the train. Or such that it is wedge shaped and can get down and under the front of the engine and not just get pushed ahead of it. That type of obstruction just doesn’t “fall onto the tracks” very often.
Most of the time when a train hits a truck or a car, the truck is just flung aside or split into two parts that are pushed aside. Very rarely does the train derail. Its only when something gets crushed and the trail rolls up and over it does it derail.
Having said that, it still happens. The Amtrack that derailed in Missouri – it hit a (full) dump truck. Of all the types of trucks to hit, yep a dump truck full of rock; that obviously was sufficient to be that unbreaking immovable chunk of metal. In this case dislodge the engine from the rails off to one side. After that, the engine is sooo heavy it just pulls the cars over a bit like how a truck trailer can yank the cab over when it takes an offramp too fast.
Dumptruck full of rock? 25 to 40,000 lbs. A Genesis P42DC (the engine of that Amtrack)? 268,000 lbs. Yeah, enough to shove it to the side just enough.
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