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Comment by felippee | Hacker News Reader

Hey, I just finished another one. A school bus with a swinging open stop sign in the middle of the freeway.

Anyway, just a food for though, autonomy really requires a lot of "intelligence" and our technology is not quite there to deal with all these bizarre corner cases. I'm glad you like it.

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You could discount that by noticing that stop sign generally shouldn't move relative to the ground. But then, you may want to notice when a police car wants to pull you over by waving that thing they wave out of the car's window...

I actually love trying to make computers deal with the real world - it quickly reveals just how goddamn complicated the real world is, and how many things we think as hard and fast are utterly arbitrary.

Right, there are cases where such a moving stop sign would actually be a real stop sign. The problem is, we try to program in the complexity that cannot be anticipated.

I think such things can be discounted by knowing that motorways never have stop signs (same with the prank stop signs). Of course, there are a lot of things that only cause a change in driving behaviour in very specific contexts. The bus' stop sign probably only applies when the bus is stopped. Similarly, in Germany at least a bus may turn on hazard lights on a bus stop, requiring everyone to drive past only at walking speed. A bus stopped on the shoulder of a motorway with hazard lights on is a different context again and thus should not trigger the same behaviour.

There are a lot of rules and laws and they change from country to country, or in the US' case, even from state to state. Self-driving cars must know these things and react accordingly. So I think the scenarios presented here are just a few (admittedly, more far-fetched than others) more contexts amidst the probably hundreds of others that already have to work correctly for switching safely between city and motorway driving, driving in a living street, observing right of way correctly in all circumstances (roundabouts, weird stuff like four-way stops, signs changing ROW for one intersection, or a stretch of road, lowered kerbs, people exiting a living street even though it's to the right, cars on an on-ramp and perhaps letting them in based on how far the on-ramp still continues, ...).

Stop signs are interesting in any case, since they have a characteristic shape. If we go full autonomous, then snow-covered signs must be correctly observed as well, at which point any octagon shape may be a stop sign (perhaps, again, depending on context). Same with signs that don't reflect well anymore at night.

The real sign SDVs are here will be when infrastructure starts accommodating their needs. Humans aren't really good at driving either, so we've invented a lot of ways to help them and direct their attention. Open manholes are supposed to be marked clearly, because people do miss that stuff. When there's snow on the road hiding lane markings, someone will come and clean it out. Signs are made to be retroreflective. Etc.

So at some point, I suppose the infrastructure (broadly understood - including laws) may be modified to reduce the dependence on cultural context and other things machines are weak at. So for instance, it won't be every sorta-octagonal shape that works as stop sign, it will be required by law to be clearly visible and also have some machine-friendly accommodations, and SDVs will be free to ignore signs without those accommodations.

(Doesn't solve the prank problem, but humans are equally vulnerable to a targeted prank anyway.)

> (Doesn't solve the prank problem, but humans are equally vulnerable to a targeted prank anyway.)

I would hesitate using the word "equally". People are actually quite robust. Particularly the second human in row will certainly not be tricked by the same prank that tricked the first one.

I want to emphasize the word "targeted" I used. Pranks involve an intelligent agent with malicious intent and an attacker's advantage - i.e. prankster is free to exploit any vulnerability of its victim. People have different vulnerabities than machines, but they still have them.

Sure they do, agree with that. But word "equally" suggest the susceptibility is the same. I would actually emphasise the difference. It is much easier to fool a machine than a human, particularly if we have a copy of the machine at hand and tinker with it (see adversarial examples for deep nets). Humans are all different, so we can never expect our "adversarial example" to be 100% certain to work.

Especially if it's a familiar road.

> When there's snow on the road hiding lane markings, someone will come and clean it out.

In Nordic countries, you don't see the lane markings for several months, they are under snow and ice. And sometimes, when it melts in April or May, you notice you have been driving on the roadside for a few months :-)

Oh, and you don't see anything at all if you are behind a truck or a bus.

In Nordic countries...

In some parts of some Nordic countries. In my part of my Nordic country we haven't had proper snow for probably about 6 or 7 years and even then it was only for a few weeks.

But more generally. If the snow clearing machines where also driver less then they might be able to run more or them more often and keep the roads clearer.

It's not just a matter of running them often. Where are you going to put all this excess snow? And operating the plows won't be free even without labor.

> Humans aren't really good at driving either,

I'm not sure where did that come from. One fatality per 200 million miles not good? Seriously, there are millions of people travelling every day. And true, there are accidents, but I think this "Humans aren't really good at driving" mantra is not really serious (but frequently repeated recently by PR of some companies).

Attentive humans are extremely good at driving, distracted humans are much worse, but perhaps the technology should focus first on the much easier task of making sure the driver attends. That would probably safe many lives, before we can have a real autonomous car.

>When there's snow on the road hiding lane markings, someone will come and clean it out.

In New England, snow can completely cover the road surface for days or even weeks at a time, and ever-changing piles of snow cover the curbs and parts of the lanes. Humans just choose a path without regard to where the lanes are in the summer. On some roads this turns a four lane road into a two lane road with a lane-width snow pile between the lanes. In a few spots it turns a two lane road into a one lane, with drivers from different directions taking turns.

Remember when Boston was about to start dumping snow into the sea because they ran out of places to put it?

Yeah, there were a few spots in my neighborhood that they gave up on trying to plow, but those of us with 4WD trucks were able to get through. Not sure how a self driving truck is going to know which snowbanks it can drive through/over and which it can't. Sometimes I couldn't tell until I tried. That was fun!

Now I really wish I had taken more photos that year specifically to illustrate this sort of thing.

But if it's that reliant on a special sensor it's quite susceptible to not only pranks but sabotage or plain old maintenance issues.

I know a few places where the stop sign is > 90% covered by bushes in summertime, and the continuous transversal white line > 90% covered by gravel (and the remaining 10% have worn off). Yet people do stop. Either because they know the place, or because they "feel" there is something suspicious (the comparative size of roads, the angle of the crossroad, the fact that there is a "pile" of gravel there, etc.). Not sure how a car could decide this by itself.

I wouldn't say never; sometimes you see them in really odd places.

That's something what's easy to train. Each of these are a bit country specific like how a road sign is mounted and where, but this is far from a real problem.

What is the real problem then?

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