ION - Waterloo Region's Light Rail Transit

[ijmorlan]

Reference? My non-expert expectation would be that in the presence of the amount of force associated with an LRV, ice will be irrelevant — it will just liquefy. I’d be interested to learn however if this is incorrect.

I'm sorry, what do you mean by "Reference"?  I'm saying that there's a very specifically engineered force that the retarders (the things that clamp onto the rail head) are engineered for.  Anything blocking the path of the bumping post will cause that resistive force to rise beyond the engineered value.  If it rises too high, you're going to cause severe damage to the train.  As it is now, the force required to push the bumping post is probably less than the force that would cause structural damage to the train.  That only makes sense.  No?

I have never seen ice just "liquefy" by being hit by something.  Can you provide an example of where this has occurred?

I don’t mean the whole block turns to water, although that would be a cool effect in a video game. Imagine a lump of ice on the track being run over by a train. To the extent the whole lump doesn’t just go flying off but actually gets run over, what will happen to it? It’s not going to divert the train upward from its path measurably; instead any ice trapped under the wheel will either be reduced to a fine powder or, I suspect, actually turn into a liquid. I just remembered that the reason skates work is because the weight of the person using them turns a tiny amount of the ice under the blade into liquid, so the weight of a train will definitely have that effect on any ice stuck under the wheels.

What we’re talking about here is of course not direct compression by the train on top of it, but the force required to move one of those retarders which is as you say specifically designed. Clearly the presence of ice will somewhat increase the required force, but in the context of the large forces associated with rail vehicles I suspect not a significant amount. So essentially I’m asking what source you have for the claim that ice will jam it up enough to affect what happens when a vehicle hits it. Just observing that the force will obviously increase is not enough.

Somebody else commented that ice is “hard as rock”. I don’t believe ice is anywhere near as hard as rock under any normal circumstances. It can seem that way when you’re responsible for chipping it off of a car, but if it were really hard as rock you couldn’t chip it off the car without damaging the car. It’s actually very soft, not to mention flexible, compared to rock. That’s why glaciers can flow.

Here is a video which is at least somewhat on point:

https://www.youtube.com/watch?v=ur5drElvAns