Quote:
Originally Posted by roger1818
Agreed, it is the scale of the relative difference. That is why I said:
I disagree with the dead part, but I agree with the part in bold. That is why I said North American trains don't rely on crumple zones, but instead:
ridged frame ≠crumple zone
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A rigid frame can't just absorb all the impact, something has to give. Physics is a thing that exists. It's claimed the FRA rules require the rigid frame to be able to withstand 800,000lb of force (god I hate imperial), so let's look at that.
If you use newtonian equations and assume a 1000 ton freight train travelling at 100km/h hits another stationary train, and that train absorbs the impact in a 1m crumple zone at the front, that force is equal to about 380 million Newtons, or 87,000,000lb force. It's been a while, but I was able to calculate this myself and there is also a calcuator
here.
87,000,000lb is quite a lot larger than that 800,000lb, so it's clear that having body frames that strong is irrelevant in a head on collision. Essentially, the entire front unit would become the crumple zone. If US trains are surviving impacts, it's not because of that rigid frame. And European freight trains can be heavier than 1000 ton, and the combined speed could be much larger, so that force number could get larger and larger, even though it's already 100x larger than the limit the FRA mandates a frame survive.
So one has to ask the question, if that rigid body frame rule is meaningless, what is the point of the rules? Why is it "better" than the European crash safety rules, which take into account many things to determine crashworthiness and safety? Which the FRA now apparently also will take into account?
Quote:
Originally Posted by roger1818
Maybe that's because you don't actually read the opposing arguments?
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If you know of any papers or articles which lay out good arguments for the old FRA rules being better with a scientific explanation, I'd love to see it but you have not presented any. I've tried to find some and honestly did try to dig up something that disagreed with what I thought. Yet there all I found are articles and papers saying the opposite.[/quote]
Quote:
Originally Posted by roger1818
That is what Positive train control (PTC) is all about. The FRA has totally botched their requirement by letting each railway choose their own (incompatible) system, making interoperability extremely difficult. I think TC has been waiting for the dust to settle down south as there has been no standard by which they can follow.
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I'm sure it is complicated and am glad for any progress, but things are far too slow. Rail safety is a joke in this country.