It absolutely is not necessary to know how another object will behave on the road: you slow down because of the uncertainty!

"It might move out of my way" is no reason to get so close at such a high speed that you can't avoid it when it doesn't!

People slow down from 35 to 30 or whatever. Humans don't slow down to the point at which an accident is physically impossible for all unexpected movements, because that would be zero considering there are frequently objects within feet or inches.

Self driving cars can emulate humans, but that won't bring them to human level performance without the ability to model other actors. If they try to mathematically rule out the possibility of accidents without such models, they won't be able to go anywhere.

That's not how traffic works at the moment. I often have pedestrians walk towards the street and I assume they will stop so I don't slow down unless they are children or similar. Almost every day I could hit pedestrians if they kept walking.

You should slow down. Those people you are describing sound like they want to cross the street, and they probably have right of way, so yield for them.

Also, my two year old will sometimes walk towards the curb, but she is very good with streets, so I am not worried. She always stops and waits to hold someone's hand before crossing. This behavior freaks some drivers out, causing them to slow or come to a complete stop, which is the nicest outcome because then I can take her hand and cross the street. When I am walking by myself drivers rarely yield even as I am stepping into the street, even at marked crossings.

I guess my point is if my two year old exhibits the behavior you ascribe to a hypothetical non-child pedestrian then how can you be sure your hypothetical pedestrian won't just "keep walking"? What if they are blind, or drunk, or reckless? Perhaps you have been lucky before and never struck a pedestrian but I strongly urge you to assess your behavior. Stop for pedestrians, it's the nice thing to do and it's probably the law where you live.

You make me sound like a crazy driver :). Just watch the traffic along a busy road with pedestrians on the side. Nobody slows down if they pedestrians behave the usual way. You also often have pedestrians walk into the road to just stop right before the zone where cars are. Nobody slows down because they see that the pedestrian is observing traffic.

I have made this observation, I even mentioned it in my comment. I am urging you and anyone else who reads my words to assess your behavior so as to affect a change in the status quo. Sometimes pedestrians do walk into the road and they do get struck. The only foolproof way to prevent this is to change driver behavior which is why the requirement to yield to pedestrians at intersections is codified into most laws.

When I am driving I often see people standing at the curb just staring at their smartphone. Usually these people are wasting time because they don't expect traffic to stop. When I stop for them they are usually pleased, they cross the road and get on with their life. Sometimes these people are just waiting for an Uber or something, when I stop for them they get confused and look at me funny. I don't mind, I just smile at them and resume driving. I am in a car, so I can accelerate and travel very quickly with almost no effort. It is no trouble for me to spend a few seconds stopping for a false positive.

In the context of self-driving cars though, they can't read expressions and exhibit them. They can't necessarily even say whether something is a person or not. So your driving methods are not applicable. A computer can say "given the physics of how an average person can move, it is possible for them to leap in front of me in X amount of time" and then what? I think that a self-driving vehicle that follows your principles without your analytic ability is going to have so many false positives it will be useless. And I think the fact that they aren't attempting to follow your principles is evidence they don't have the ability.

I agree, and perhaps self-driving cars are not yet ready for "prime-time". The solution for the current state of the art might also just be maintaining a lower speed with automated drivers, which may also necessitate limiting the types of roadway on which they can operate. A slower average speed shouldn't be a big problem for automated cars since they don't experience the frustration of human drivers. Given wide-enough adoption, accomodations can be made to traffic signalling apparatus, car-to-car communication, and car-to-cloud integration to develop near-seamless traffic flows, allowing shorter travel times even at slower speeds. From here the tech could be iteratively improved to provide faster speeds without compromising safety.

Thanks! That's exactly my point.

This only works if you don't have other cars run into you when you slow down unexpectedly. I am not saying that current traffic is sane but just saying "always also down when you see pedestrians " just doesn't reflect reality. In CA you often have speed limits of 45 right next to houses with driveways. Either you play it safe and go 20 or less and get cursed at by other cars or you go way too fast to respond to unexpected obstacles.

When I am driving I routinely check my rearview mirror and assess the following distance of the cars behind me, so I usually know I will not be rear-ended when I am stopping for pedestrians or for any other reason. If I am driving and I notice someone is following too close for our speed I will tap the brake lights so as to encourage them to increase their following distance. If this fails I will slow down to a speed where their following distance becomes appropriate. If they are an uncommonly aggressive driver I might even pull over or change lanes and allow them to pass, I certainly don't want to be rear-ended! That said, even if I were to fail at this, I would prefer to be rear-ended stopping for a pedestrian that would have stopped than to strike a pedestrian who failed to stop walking into the path of my vehicle.

The speed limit is a reference to the maximum allowable speed of the roadway, not the minimum, only, or even recommended speed.

You clearly never have driven a busy four lane street in LA with bicycles and pedestrians mixed in. What you are saying makes sense in theory but nobody drives that way.

I do drive this way, most often in Seattle which has no shortage of the behaviors you're referencing. You can drive safely too because you are in control of your vehicle.

I didn't always drive like this, but I was in an accident that was my fault that totally upended my life, so I made an effort to change my ways. You can do it too, before you get in an accident that sets your life back, or irreparably shatters it...

I recommend taking an advanced drivers education course if you seriously decide you want to improve your driving. A lot of this stuff is covered.

Stopping unexpectedly does not cause accidents, locking down on your brakes unexpectedly causes accidents. In fact, in the US the person who hits you from behind will be held at fault no matter how hard you hit your brakes or why, because they are expected to maintain sufficient distance and attention to stop when you do.

If a light application of the brakes causes the car behind you to slam into you, the fault is with the idiot tailgating you, while playing with their phone.

Nobody's suggesting that anyone should slam the brakes every time a moving object intersects your vector of motion.

> You make me sound like a crazy driver

No, you did that:

> I often have pedestrians walk towards the street and I assume they will stop so I don't slow down unless they are children or similar. Almost every day I could hit pedestrians if they kept walking.

With respect, I don't know what you meant to say but that sounds like a description of a bad (or at least inconsiderate) driver to me.

In any case, when I think about how I would design a self driving car, an "auto-auto", the first principle I came up with was that it should never travel so fast that it couldn't safely slow down or break to avoid a possible collision. This is the bedrock, foundational principal.

> I often have pedestrians walk towards the street and I assume they will stop so I don't slow down

> the self-driving system software classified the pedestrian as an unknown object, as a vehicle, and then as a bicycle with varying expectations of future travel path

Little different, huh? If you see something that looks like it might be in your way, and you aren't sure what it is, you just keep going?

And if I see a pedestrian in the middle of the road at a random spot, especially at night, I'm slowing down since I don't know WTF they're thinking. Or if I'm in a neighborhood with regular street crossings carved out of the sidewalk and someone's coming up to one of those - I don't know how well they're paying attention to their surroundings.

I can tell pretty quickly if something is pedestrian or a bicycle and plan accordingly. In addition I can tell where the pedestrian is looking. Sometimes I slow down, sometimes I don't depending on how I assess the situation.

I think it comes down to the fact that the classification algorithms are not ready for primetime.

You don't need to stop if you're uncertain, but you should slow down. That makes it easier to stop once you know you have to.

with significant fuzz factor, agreed. If i'm on the sidewalk and take a step toward the road, should it make the car jerk? Probably not, it's a hard call for passenger comfort. From another angle, think of subway tracks - the algo your describing would slow to a crawl as it crosses every station.

> From another angle, think of subway tracks - the algo your describing would slow to a crawl as it crosses every station.

As far as trains go, they do slow down when passing trough a track adjacent to a platform. There are some non-platform adjacent tracks the train companies use to avoid slowing down, however they will slow down or even stop if something is going on.

Similarly, high speed rail doesn't have level crossings due to safety considerations. Overall trains are very safe and they are _designed_ for safety. It is highly irresponsible and immoral to just wing it with people's life/safety.

> It is highly irresponsible and immoral to just wing it with people's life/safety

100% agree.

> As far as trains go, they do slow down when passing trough a track adjacent to a platform. There are some non-platform adjacent tracks the train companies use to avoid slowing down, however they will slow down or even stop if something is going on.

The equivalency isn't 'trains slow down through stations' (That would be cars having lower speedlimit in pedestrian areas - they do and the ubers honor) , it would be 'train spikes breaks if someone takes a step toward the edge' (Which they don't, even though it would potentially save lives).

There's always a tradeoff between usability and absolute safety. I'm not saying the uber did nothing wrong, at a minimum it should have spiked it's breaks. The 'perfect world' solution would be the uber knowing mass and momentum of approaching objects, and whether they could stop in time. But honestly, here would that have helped? We'll never get rid of people walking in front of moving cars, just have to be find the happy balance (which we clearly haven't)

> 'train spikes breaks if someone takes a step toward the edge' (Which they don't, even though it would potentially save lives).

A train's deceleration under maximum braking is far, far lower than a car. [1] suggests 1.2m/s² (paragraph 8).

[2] says the deceleration of a low-speed train crashing into the buffers at the end of the line in a station should not be more than 2.45m/s² (paragraph 35). That caused "minor injuries" to some passengers.

Trains do slow down earlier if the platform they are approaching is very crowded, but there's not really anything else they can do.

[1] https://assets.publishing.service.gov.uk/media/547c906640f0b...

[2] https://assets.publishing.service.gov.uk/media/547c906640f0b...

With trains, nothing else is supposed to be on the tracks.

With cars, there is an expectation that you have to share the road with other vehicles, objects, obstacles, pedestrians, etc.

> If I'm on the sidewalk and take a step toward the road, should it make the car jerk?

No. That's my point. Take less drastic measures earlier, and only escalate when you have to. That's how I drive, and a self-driving car can do the same.