Comment by 1718627440

So that's a lot of questions, that I all can't answer in full.

> Would you mind sharing some more of the why it is still an open problem?

Because for train sensors, there is a small drift which accumulates too much, hence it is synchronized by magnetic position markers in the tracks.

> I understand satellite positioning isn't definitive

Yes, and the point is it might be some solution if we would have the safety systems from 1860. But we do not and hence it needs to be more accurate than the current system, and it is not and in addition also more expensive (and subject to remote influence and reliance on potentially adversary nation states).

> Sorry for the bleak introduction of economics

No, economics is basically the primary constraint for safety. We could pay million people to make sure a single person does not stumble if we want total safety, but that's completely pointless, and also these million people would starve, because no one is producing food anymore.

> But even as a tertiary or lower risk mitigating factor

But for that it's too expensive and still unreliable. There is RCAS[1], which I already linked elsewhere in the thread. That's basically cutting edge and too expensive to introduce everywhere. Also previous safety systems are already not rolled out enough, which is causing these accidents, so rolling out yet another expensive system is not going to improve much.

> But what track you are on, isn't that obvious to the human in the cabin?

Yes, but if it is already known, why use GPS to calculate the same information with more error?

> So could a vision based solution help count tracks from left to right?

If the train driver or dispatcher makes use of vision to assess the train position, the error will be higher than the current sensor/electric-resistance based system.

> Assistant: "US PTC [...]

BTW, that seems to be a verbatim quote from https://news.ycombinator.com/item?id=50288518 Yes, there are less accidents in planes than in trains, but this is due to what I already explained.

   [1]  https://www.dlr.de/en/kn/research-transfer/projects/next-generation-train/rcas-railway-collision-avoidance-system