I’m not really sure if this is your specialty or not, but I was wondering about the plausibility of jumping from a moving train (think an older steam engine, not the almost too fast modern Asian trains). I think if it’s rounding a bend, it’ll have to slow down and make the jump easier, no?
There’s a number of factors here, but this should be survivable under, at least some, circumstances. Some of this stuff also applies for bailing out of a modern car, or any other vehicle really.
From what I know, the maximum survivable speed you can bail out at is around 25-35mph. More than that, and you’re going to be suffering some pretty serious injuries on impact, even if you do this perfectly, simply because of the relative speeds. 35mph is also the lower end of the cruising speed of a 19th century steam locomotive. So, these do barely intersect.
Leaping from a vehicle safely depends on a couple additional factors. A soft landing point is ideal, and really anything that can blunt the initial impact is important. (Padded clothing is a huge boon here.) Leaping away from the vehicle so that you’re not clipped (or crushed) is vital. Keeping your limbs close to your body, so that you don’t break them on impact is also important. This means resisting the instinct to use your arms to break your fall. Obviously if the vehicle is above 30mph, trying to find a way to slow it is also on the list.
Depending on the train and tracks, sharper bends will force a train to slow down, so, that part does work in your favor. Note that phrase: “Depending on the train and tracks.” It’s entirely possible to have a bend in the rails designed to be taken at cruising speed. The relevant factor is how much the train has to turn. The maximum speed for a given bend is dependent on a lot of factors including: The weight and length of the cars, and the train as a whole, the coupling used, the width of the track, the track’s grade, and adverse weather conditions. For example, heavy cargo cars cannot take bends as easily as lighter passenger cars. Even then, on a sharp curve, the train will have to slow down. Depending on the rails and the cars, it’s possible it could slow down to as low as 5 to 10mph. Jumping off at those speeds would be completely survivable, assuming nothing horrific happened.
You’re also correct, you can’t jump from a bullet train and live. These are, specifically, designed to keep their speed up, even while turning. Technically, they will bleed speed to turn, but it’s still several times above survivable thresholds.
In the US and Candada, diesel passenger trains run around 80-90mph outside of urban areas. (Amusingly, the Canadian train system never converted to metric, so miles is correct.) I know there’s reduced speed limits in urban areas, but don’t know what that is exactly. Additionally, different tracks may have their own posted speed limits, and those limits can be affected by severe weather, or other temporary factors. This puts the train’s velocity well above survivable bail out speeds, even on most curves.
One problem that does come to mind is the idea of bailing from a runaway train. That’s not going to be survivable in most circumstances. A character who’s being held captive on a train with an engineer who’s being mostly responsible has options, however a train careening out control will, almost certainly, be going too fast to safely bail out of.
Incidentally, trains in the New York City subway system move at an average of around 17mph. While jumping out of one is still an incredibly bad idea, because of all the risks associated with being around a moving train, that is a survivable speed. NYC’s transit system is infamous for how slow it is, however. Some other metros will be slow enough to allow someone to bail, but you’d need to look up the city in question if you’re wanting a specific answer.
So, yes, you can jump from a moving train and live, if you know what you’re doing, and it’s not going too fast.