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Comment by mrtksn | Hacker News Reader

Actually, the speed limits are not imposed randomly and you can usually "sense" the limit from the surroundings and the structure of the road. I don't really look at speed limits when driving, if I'm on a road that looks like a pedestrian can walk then I probably need to go slow and if there's a school ahead or the street is particularly narrow or the road pavement is not asphalt I probably need to go extremely slow.

TBF, now I'm not in Germany but when I was, driving on the autobahn usually involved religiously following the signs of speed limit and no speed limit(the limit-free coverage on the autobahn is patchy).

I wonder if the self driving systems asses the road type to determine the speed they should go. Is there a possibility for a autonomous car to speed up to 120kph around a school or in a residential area if the sign is missing or someone puts a bogus sign?

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> Actually, the speed limits are not imposed randomly and you can usually "sense" the limit from the surroundings and the structure of the road.

This is, in fact, the legal standard in California! The actual speed limit is the minimum of (posted speed limit plus a substantial fudge factor) and (a subjectively safe speed for the road conditions). i.e. if the sign says 65mph, and the road is winding and a bit icy/rainy so that 45mph is the highest safe speed, you can be ticketed for speeding if you drive 60mph.

How is that enforceable? Is there a legal standard? Is it borne on the judgement of an officer?

It's enforced by the courts generally with fines. You can lose your license with repeated infractions.

The legal standard, like many legal standards, is around reasonableness. Regardless of the posted limit, you may never driver faster than is safe for the current conditions.

And it is indeed borne on the judgement of the officer. Who else would ticket you?

I know it’s not the correct way to do, and it stems from my experience driving, but I’ve always used the first digit in the speed limit signs for bends/corners on mountain roads as a guide for the gear to be in. 25mph curve? Whatever speed you can do in second is fine. 45mph, fourth gear speeds, etc.

Not entirely related but yeah, depends on road conditions and signage.

when there's a construction and the speed limit is 60kph, I really hate it when the car starts accelerating like it's in a race track the moment it sees the limit removed. it scared me a couple of times, so I imagine it's not impossible for that to happen.

it also takes the curvature of the road into account and slows for the traffic, but there's always a small empty town with straight roads...

it also sometimes messes up the steering when going through a construction site with yellow lines, so I really hope that they improved this system heavily in the last year since I bought my car.

Signs are also frequently wrong, even in Germany. This can get so bad that there are multiple maximum speeds on the same road in the same direction, all depending on where you came from.

No, the speed limit is always the same, regardless where you came from. If there is no speed limit posted after a junction, the default speed limit for this kind of road (unlimited, 100km/h, 50km/h, or zone specific as posted before entering the zone, usually 30km/h) applies.

But even a lot of Germans don't know this, I'm afraid.

> But even a lot of Germans don't know this, I'm afraid.

Yes, because this is not the case.

https://www.bussgeldkatalog.de/geschwindigkeitsbegrenzung-au...

While this is true it's also not uncommon for signage to be faulty, i.e. not following official regulations, or invalid unfortunately. Most often at construction sites.

My driving instructor also told me this. I learned the hard way with a pretty hefty ticket.

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