Hacker News Reader

Comment by nmehner | Hacker News Reader

I always wonder if this is a problem that has to be solved at all. Instead of cars recognizing the speed limits there should be government managed maps containing all the roads/lanes and speed limits. When creating a construction site just add it to the map.

If you can legally rely on the speed limits in the maps, this should be much easier to do.

Recognizing speed limits seems to be a technical solution to an organizational problem.

View on HN

In Germany a speed limit doesn't mean it's always reasonable to drive at maximum speed.

E.g. there are narrow streets in citys with cars parking on both sides. The official speed limit is 50 km/h. If you drive at this speed you straight up murder any pedestrian coming out behind of a car. If you do this you'll be pleaded guilty, because your speed was not appropriate to the situation. You even have to learn this exact situation when you make your drivers license.

An other funny example. Where i lived was road with a bend, where an ordinary person should maybe drive 50 km/h. It was borderline questionable to drive through there with 70 km/h and a good car. Directly before the bend the speedlimit changed from 70 km/h to 100 km/h. There where a lot of accidents, because even germans don't understand the meaning of german speed limits.

I’ve noticed this on Polish vs Czech roads (I’ve driven mostly in the mountains border regions of Czechia so this maybe local). Polish roads have gazillion of signs and usually you’ll see a lower speed limit sign just before the curve or a bend if it’s not supposed to be driven at the speed limit of the main road. In my opinion there are way too many signs and I feel—as another poster commented here—like a robot. On the other hand in Czechia on a small mountain road there’s a general limit say 90kmh or 70kmh and there’s no way you make the bends with that speed— it’s your responsibility to slow down.

I’ve seen a similar differences in another border regions, e.g. Switzerland-France or France-Germany. It almost seems like there are two schools of thoughts that different countries subscribe to.

I Drive much and Usually I and others get curves etc more intuitively. One has to be a really bad driver to not have a Instinkt for the speed necessary in curves. Btw German driver here and I find German has a good equilibrium of signs . I have to drive to Paris and Milano for work . Those places are pure mayhem of signs and confusion. I can’t imagine a self driving car mastering some of those places.

The borderlands are like that, yes.

Prague, on the other hand, is oversaturated with signs. I guess someone makes money on them, because some are clearly superfluous (Segway bans in distant neighbourhoods where no one ever drove a Segway; Segways were only a bane of the touristy center).

The reason why Polish roads have so many signs is because producing and installing them is an opportunity to make money :) And usually that opportunity goes to a company owned by a relative of some local politician ;)

> In Germany a speed limit doesn't mean it's always reasonable to drive at maximum speed.

I didn't want to imply this. I was just talking about the task of finding the speed limit. Getting from there to a reasonable speed to drive at is a different issue and much more complicated, yes ;)

> Recognizing speed limits seems to be a technical solution to an organizational problem.

It's probably the easiest task for an autonomous system. So if your car can't do that, then probably it's safer to drive it manually.

Recognizing the signs is probably one of the simpler tasks, yes. But for example the StVO (traffic law: https://www.gesetze-im-internet.de/stvo_2013/BJNR036710013.h... ) in Germany says:

"Das Ende einer streckenbezogenen Geschwindigkeitsbeschränkung oder eines Überholverbots ist nicht gekennzeichnet, wenn das Verbot nur für eine kurze Strecke gilt und auf einem Zusatzzeichen die Länge des Verbots angegeben ist. Es ist auch nicht gekennzeichnet, wenn das Verbotszeichen zusammen mit einem Gefahrzeichen angebracht ist und sich aus der Örtlichkeit zweifelsfrei ergibt, von wo an die angezeigte Gefahr nicht mehr besteht. Sonst ist es gekennzeichnet durch die Zeichen 278 bis 282."

The translation of this is: If a speed limit is combined with another sign indicating a reason for the speed limit (e.g. construction work, dangerous curve, train crossing...) the speed limit automatically ends without any additional sign.

So basically the AI has to understand why the speed limit is there and decide when it has passed the dangerous part of the road.

When starting to drive the car has to recognize if it is inside the city (50km/h or 30km/h limit depending on location), outside the city (100 km/h) or on the autobahn (no limit). This is simply impossible without having a map. You could save the state from the previous drive. But what happens if the car gets towed from the autobahn into a city. Will drive through the city without any speed limit?

I don't think this is simple at all.

That sounds like an exception that could be easily addressed by adding an additional sign or perhaps in most cases making the rule hold for a maximum of 100 yards or so. Even detecting construction work is relatively easy: you have lots of cranes, people wearing helmets, cement mixers, scaffolding, traffic cones, yellow tape, etc. Easy to teach to a machine learning system.

Very true, it's kind of like when you try to automate existing human processes. There are often too many exceptions to make it easy enough to automate, compared to a company that automated this process from the beginning. Humans are very good at exception handling, albeit slow, and this is implicit in any process involving humans.

Standardization is necessary for good automation.

I think Germany has this, not sure what it’s called but newer cars seem to have this

Reply on news.ycombinator.com