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Comment by vlunkr | Hacker News Reader

This would probably be easy to exploit. Someone could drop a bunch of random invisible stop signs.

to be fair someone could also go toss a steel bar on some railroad tracks or drop rocks from the top of a highway overpass.

Right, but that's rather obvious.

It's true that people aren't often looking for fatal pranks, but you could do more benign like try to get people pulled over by causing them to speed unknowingly.

Someone could really just weld a steel bar onto a railroad track out in the wilderness and derail a train??

Are you genuinely asking about the feasibility? If so, then: yes.

Yes. Railroad tracks in the middle of nowhere are usually freely accessible. Why bother putting a fence if no one's around? Even at railroad crossings in cities, one could cause a some collateral damage by welding it right next to the crossing.

Yes? No welding required, just a few thumbscrews, if you use one of these:

https://westernsafety.com/nolan-portable-derail-pd-2/

On sale now! Or pick this one for bigger and faster trains:

https://www.aldonco.com/store/c/127-SaberTooth-Portable-Dera...

There are lots of tools, weapons, chemicals, and other things that a person could do that would be bad. It doesn't take much creativity, just a callous disregard for other people. But in contrast to the fearmongering and crime you'll see in the media, consider it a bit of good news that in spite of how incredibly easy it is to intentionally cause harm to someone else, billions and billions of people choose not to do that every single hour of every single day.

I mean, you now have told a lot of people that you can just get a tool to derail a train easily, that I'd guess most (I didn't) don't even know it exists.

I think that's GP's point: derailing a train is just a search engine away, and that's only scary when we think about it, which we almost never do.

Which in turn is because our emotions around people setting out to do that, are calibrated around the fact that it basically doesn't happen outside of war conditions.

I googled how to do it just for lulz and got youtube video with someone showing one... and some russian/ukrainian looking name in comments asking about it and asking where to get one, from like a month ago

https://www.kyivpost.com/russias-war/anti-putin-russian-rebe...

I wonder whether it's related. Probably not but train derailments are weirdly relevant to current world state...

But back to the topic... I don't think anything should be censored and am of opinion freedom of speech just need to be taken wholecloth, good with the bad, but you gotta wonder how much easier it is now.

You don’t even need to weld it, you just need to leave it somewhere in the way and striking it at sufficient speed will result it in bludgeoning through a car or worse.

An improperly stored rail from a maintenance project derailed a NYC subway train in 2017: https://apnews.com/article/a6a01e5928f9478bab0d33f03260870e

Its hard to derail a train.

https://youtube.com/watch?v=agznZBiK_Bs

AFAIK, at least in Russia there are signaling systems that will interpret a metal object connecting the rails as "another train is on the track" and inform the train driver.

Not sure whether those systems are also installed in the wilderness though. But it seems kinda likely that anybody thinking "I should derail a train for fun" might not bother driving into the wilderness when there's an alluring, convenient, seemingly unobserved stretch of the railway available nearby.

Edit: another thing that comes to mind is that you'd also have to find a low-visibility part of the railway, even in the wilderness — because otherwise the driver will just notice the obstacle and stop the train.

Tag the coded signs on a GPS map. If the detected "sign" is not on the GPS map the system can label it as "probably malicious".

Plenty of places have no reliable GPS reception.

Then why use the signs at all rather than just use this gps based road rule database

Because not all cars are self-driving or have the ability to access this hypothetical database. That will remain the case for likely the next 30 or more years.

Right, but the cars that are scanning signs and will have the ability to read said code are the ones being suggested that they should consult this database to avoid errors. If they're consulting it to avoid errors, they could just use it directly

Now you have two sources of truth for autonomous and non-autonomous cars. You end up with two groups playing the same game by different rules on the same board simultaneously.

Whether or not that's a problem in practice is not clear to me. Among others, taxis, construction vehicles, emergency vehicles, garbage and delivery trucks, municipal busses, school buses, bicycles, motorcycles, and vehicles in funeral processions all play by different rules than the average motorist.

This mostly doesn't cause disasters. Of course they're visibly different for the most part and make up a comparatively small percentage of traffic.

Ride hailing vehicles might be an interesting point of comparison: they're visibly similar to normal vehicles, comparatively common, and play by something resembling taxi rules.

honestly if we're going this far we may as well embed a speed system in the road itself and have the signs for redundancy.

I can see potential problems with temporary signs, such as those put up for road works, around accidents or for police enforcement.

That's why we need to sign the signs.

And use a blockchain to track every interaction between passing cars and the sign. Which makes speeding tickets all that easier.

https://xkcd.com/1958/

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