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Comment by indigodaddy | Hacker News Reader

How do AI cars fare with those instinctual "decide which way to swerve in a split-second" scenarios that come up maybe once every 10-20 years over the course of a driver's history?? It's happened to me about 2-3 times and I've always made the "(assumedly) correct" split second swerve decision. Wondering if that is a "human/instinctual" skill and if AI cars do just as well or better, or perhaps not as good? I don't have any evidence backing this but my gut tells me these scenarios are something that a human driver would handle better than AI.

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They test extensively on those types of scenarios. See: https://waymo.com/research/collision-avoidance-testing-of-th...

Blog post for the paper: https://waymo.com/blog/2022/12/waymos-collision-avoidance-te...

> those instinctual "decide which way to swerve in a split-second" scenarios that come up maybe once every 10-20 years

The correct answer is almost always to hit the brakes. Not to swerve. And Waymo will hit the brakes earlier than you or me.

I would be interested to see waymo adapt to the snow and ice, where “hit the breaks” Is the wrong answer, and the correct is to drop the car into neutral. I believe waymo will figure this out in time, nut SF and Phoenix are idealized driving conditions.

> snow and ice, where “hit the breaks” Is the wrong answer, and the correct is to drop the car into neutral

This is only true with 2WD and no automatic stability control, and if you’re going down a slope. For every other case, ABs will out perform in snow and gentle braking will evenly distribute traction force with stability control doing microsecond evaluations.

It is also the case that Waymo will be dramatically better than all humans in ice because it is going to take the aviation approach and stay in the depot, rather than fooling itself into believing it is competent at driving on ice.

You still need to be in neutral as the ABS/stability control doesn't control the engine. 2wd makes no real difference other than rear wheel drive tends to be the most susceptible to this issue, but any wheel can lose traction.

> stability control doesn't control the engine

Stability control is tied to power in all modern systems.

I spend about 5 months every year driving in snow and ice - this is the first I'm hearing about dropping it into neutral. Can you elaborate on when that would be appropriate? Obviously you shouldn't be slamming on the brakes, but they do work fine in snow and ice. I don't see how rolling into things while not in gear is an improvement?

I think it's often about when you're on rural single lane roads and perfectly bad ice/snow/slush conditions where you need to keep your speed very low, and sometimes even very moderate braking can cause your vehicle to veer off the road and into a snow bank, not necessarily the need to avoid something in front of you

They mean go into neutral and lightly brake. In a 2WD car, the braking force applies more strongly to the non-powered wheels. Since those were traditionally the back wheels, this meant when going down a hill the front wheels would have more traction. Those are also your steering wheels, which means them locking up is bad. Again, this is the sort of advice that is germane in highly restricted environments which become folk knowledge and later mis applied by humans in ways that reduce safety.

(You also only get into this scenario when your stopping distance is shorter than your reaction time and perception length. Something automated drivers can manage better than humans.)

I remember being taught the neutral trick for emergency braking back in the 90's, and it had nothing to do with traction in poor conditions. It was simply to remove any engine power that might extend your braking distance. It's definitely bad advice in any modern car.

When you let off the throttle your wheels start driving the engine and slowing you down. In snow/ice that engine breaking alone can be more braking force than is safe and so you go into a skid. Shifting to neutral removes engine braking and allows for more controlled slowing down.

When it's those conditions though I just use a light touch on the throttle to make wheel speed match ground speed, a lot of easier than trying to shift in and out of neutral.

I think the OP means in a manual transmission. Auto will decouple at low speeds / engine braking won't be as severe. In a manual car, in 1st gear, I could possibly see it.

As someone who grew up BEFORE ABS, drove in the winter (in Canada), including first winter owning my own car with sport tires because I couldn't afford winter tires, spun / slid a few times even with top-of-the-line winter tires, etc.

ABS is a game changer in the snow. I used to go to an empty parking lot every winter during early snowfalls to play around and skid, start/stop, etc. Even EARLY ABS ('94 VW) means that 98% of the time (IMHO), the answer even in snow/ice is "slam on the brakes". Sure, you might have a few percent longer stopping distance than an expert who can do threshold braking - are you an expert? And the fact that you don't lose control of the steering is a huge advantage.

If you are in a situation where your car is sliding, like down a slick hill. You dont hit breaks, you put the car into neutral and steer into the way your car is sliding to try and keep the car on the road.

The correct answer is to not drive so fast (or at all) in conditions where braking might lead to a skid. I'd expect an autonomous vehicle to be rather better at this given they can hook directly into the electronic stability control system in a vehicle and constantly monitor temperature (and ideally measure upcoming road temperature).

Also, shifting into neutral is really only a thing for old vehicles without ABS/ESC. In modern vehicles, you let your foot off the gas slowly.

I am in upstate new york, unless the situation is extremely bad, just dont drive isnt a valid answer for 5 months a year.

If hit the brakes is the wrong answer, you are driving too fast.

Almost all of these tricky situations are avoided by slowing down and giving more space around hazards.

? just brake and rely on the abs

I disagree. High percentage of these scenarios are at speeds and scenarios where hitting the brake would not prevent a collision and a quick swerve is the only option to not collide. Obviously your quick swerve could cause another collision so I guess it's which decision on average causes the least harm/death? I agree though that most people's extinct would be to brake. Mine never has been though.

> quick swerve could cause another collision so I guess it's which decision on average causes the least harm/death? I agree though that most people's extinct would be to brake

If it’s 1989 and you don’t have ABS, yes. Otherwise, swerving is a gamble [1]. If you don’t have time to stop, you physically don’t have time to evaluate and choose a right or left swerve. You’re trading the certainty of a head-on collision with whatever is in front of you against the uncertainty of what’s to the right or left, compounded with all the fun that comes with a side/tumbling collision and increased risk of not hitting a car.

[1] https://peterhancock.ucf.edu/wp-content/uploads/sites/12/201...

If you cannot brake you are following too close. I know everyone else does it (except 3/4ths of semis!), but you can be the one who maintains a long following distance and thus can stop in time. Every time setup the long following distance 5 cars jump into the gap - but then the gap remains as no more do.

what about when there's an idiot slightly ahead and in the next lane who decides to randomly swerve into my lane?

do you also maintain a long following distance when there's a car right next to you in the next lane? I try to, because I don't want to stay in someone's blind spot, but sometimes it's not really possible to fall back.

> what about when there's an idiot slightly ahead and in the next lane who decides to randomly swerve into my lane?

You're safer hitting them head on while aggressively braking than attempting a microsecond swerve.

Is your nickname anti-swerve or something? Have you never swerved even once in your life?

"what about when there's an idiot slightly ahead and in the next lane who decides to randomly swerve into my lane?"

Exactly, this is the situation I am mostly talking about.

I watch a lot of car accident videos and I've seen that happen exactly once.

Perhaps you mean the far more common scenario when the car in the next lane simply decides to merge into yours? Nothing about that is random[1] and the response in 90%+ of cases is just to let off the gas for a few seconds. That's it.

[1]: In most cases, it's because your lane is open and theirs is about to be backed up. You'd want to switch lanes too, so it really shouldn't be surprising they do.

The rest are mostly people realizing at the last second they want to turn right/left at an upcoming intersection (or highway exit). Again, predictable.

Because all the "person doesn't look, pulls out into road, other traffic swerves around them" don't cause crashes and don't get posted to your accident feed.

FFS, this is like selection bias 101.

I watch accident videos, not crash videos. Pulling out/switching lanes while not looking is like 40% of the clips in the videos. It's a common, predictable driving scenario, nothing to get one's panties in a bunch about.

Here's a classic example with an explanation: https://youtu.be/kTczmnkz824?t=882. No experienced driver should be surprised here.

Right, so you've created a dangerous scenario by speeding and by the direct consequences of your actions you're now forced to execute a dangerous manoeuvre of swerving. Maybe, just maybe, the solution is not speeding.

> I agree though that most people's extinct would be to brake. Mine never has been though.

...

You operate a motorized vehicle and your first instinct when seeing anything dangerous ahead is to do something other than braking?

There was a notable case recently where the Waymo did swerve, to avoid someone who had fallen off a scooter into their lane (video here): https://www.reddit.com/r/waymo/comments/1hfvb5o/waymo_visual...

Hard to say for certain, but it looks like just braking probably wouldn't have avoided the collision.

I’d argue that’s more straightforward collision avoidance than a swerve since the rider was to the side when Waymo turned. As such, there wasn’t a choice between braking and swerving. One had to do both, and there was no real optionality as to whether to swerve right or left.

It's just ape hubris that makes you think these were the right swerves instead of just dumb luck that you did not flip over the center barrier head-on into a school bus.

The Waymo doesn't have to swerve as much as a human because it can see a mile away and never blinks, and it knows that the right thing to do in every swerve-worthy situation is to slam on the brakes to take the energy out of the event. It also drives around with the brakes pre-pressurized because it isn't trying to compensate for the fact that its control system is partially made of meat. Anyway you can go to r/waymo or r/selfdrivingcars for lots of videos of Waymos avoiding objects.

Far quicker and with better situational awareness probably.

Those instinctual human responses can be wrong/misguided as well and can have pretty serious ripple effects (e.g. most chain collisions after somebody panics and steps on the breaks). And even when those instincts work correctly, they rely on driver focus and attention; which to put it mildly is not very reliable. The lack of that is a well known root cause of many accidents. People get tired, distracted, etc. or become otherwise unfocused from driving safely. And of course some drivers are simply not that competent, barely know traffic rules or how to drive safely. The barrier for getting a drivers license is pretty low. And all that is before you consider road rage, drunk drivers, elderly drivers with cognitive and visual impairments, and all the other people who really shouldn't be driving a car.

If you rank AIs against most drivers, they probably hit the top percentile in terms of safety and consistency. Even if you are in that percentile (and most drivers would likely overestimate their abilities), most human drivers around you aren't and never will be.

Traffic deaths in the U.S. are staggering — annually far exceeding the fatalities of most U.S. military conflicts since World War II, including the peak years of the Vietnam war. It's hard to do worse than that for AI drivers. The status quo isn't very safe. Most of that is human instincts not working as advertised. People really suck at driving.

Probably better? 'Who' can process more data faster is likely impossible to answer, but (e.g.) Waymo can train on those scenarios and have way more 'experience' than any individual driver who's seen it once every 10-20 years of their driving career.

Yeah it's interesting, these scenarios are generally at high speeds on an interstate highway, and generally involve some level of predicting what the villain driver is going to do (split second prediction though mind you, it all happens in the blink of an eye), and sometimes the right thing to do is to swerve (if no one is adjacent in surrounding lanes) whilst either not using the brake at all or almost no braking. Basically avoid the brake and do your quick swerve after you've confirmed there is no one in the left/right adjacent lane or close enough behind you. Once again this all happens in the blink of an eye. Perhaps AI would be better? I'm not complete sold though..

One big difference in favor of the software is your "after you've confirmed there is no one in the left/right adjacent lane or close enough behind you." The car has been looking in every direction the whole ride. The car already knows what there is to know about all the neighbours. A huge advantage over the human driver.

I feel also that the car having a far better experience of its kinematics / dynamics / features is also a huge advantage - see the good old drifting parallel parking videos.

After that there is the concern about computing reaction time. Can it get stuck hesitating? Clearly the cars hesitate a lot in generally safe places. But we have seen some videos already of a Waymo very smoothly dodging someone running out from in between cars (they were already tracked), and someone mentioned a scooter incident. Hopefully we'll see more videos of emergency responses.

Another comment mentions "r/waymo or r/selfdrivingcars for lots of videos of Waymos avoiding objects."

- Humans have awful reaction times, so the "AI" cars should fare 10-100x better. "split-second" is laughably slow to a computer.

- How seldom these scenarios come up for human drivers is a huge disadvantage for them. For self driving, it doesn't matter, the cars' reactions can be simulated in arbitrary scenarios as many times as needed, so even the rarest of scenarios can be ensured to be handled properly.

- There's nothing special about the decision to swerve vs to say, brake. I'd expect self driving cars to not need to swerve nearly as often because the need to swerve probably only ever exists due to excessive speed and/or poor following distance to the vehicle ahead.

> It's happened to me about 2-3 times and I've always made the "(assumedly) correct" split second swerve decision.

Easy question: Did you make that decision with full awareness that you would not end up in a collision path with another vehicle by swerving? Oops.

Even if you did, how many drivers do you think would "instinctively" swerve into another lane and get hit by an oncoming vehicle because they do not maintain constant situational awareness around their vehicle? The majority, at least.

I'm ok if the AI car makes an incorrect decision once every 10 years.

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