Hacker News Reader

Comment by ddalcino | Hacker News Reader

Would you care to elaborate on what went wrong? The other comments here make ‘automatic emergency braking’ sound like a really good idea, and it’s hard for me to imagine that this particular feature would be so problematic.

If you’re talking about other automatic steering features, that’s very different, and your comment makes more sense to me.

View on HN

Not the person you were responding to, but here's an anecdatum:

One time I was driving behind someone under otherwise normal conditions, and they turned right into a parking lot. As they turned right, they obviously began exiting the road. The screen on my car screamed "BRAKE!" and then the braking system activated. They were about 60% of the way into the parking lot, and continuing to exit. I was at a normal following distance, going a normal speed, and they were just making a right into a parking lot. This was a very ordinary situation, and the emergency warning was unexpected.

Now, technically, if that car had completely stopped for some reason instead of continuing to exit, I guess I could have hit the back corner of the bumper. That is, if I hadn't, you know, shifted a couple feet to the left to avoid it.

Ironically, the emergency braking alarm was so distracting that it might have caused me to hit the car in front of me if the brakes hadn't activated, and if I had needed to steer to avoid an accident.

And if the person behind me hadn't seen my brakes suddenly activate, they might have hit me. Or, if the person behind them hadn't seen their brakes activate, they might have hit them. And so on.

I've had this exact situation happen on numerous occasions. It's always people turning into a parking lot ahead of me, in a situation where they will absolutely be out of the way long before I reach them, but also I'm actively shifting to the side to go clearly around them anyway. In none of the situations was there any chance of an accident even if the turning car stopped suddenly instead of completing its turn. And this has happened to me on multiple different vehicles.

Each time it happens my immediate reaction is "what the hell is wrong with my car" before I see the "BRAKE" on the dash or heads up display and realize this happened yet again. I'm surprised I haven't been rear ended on account of it yet.

I fully understand that frustration, but I would point out that continuing through the departure zone like that at full speed is prone to accidents with another car entering the road in that blind spot and you should adjust accordingly. Additionally, following the car in front of you so close that you hit them if they brake suddenly is inherently dangerous and a bad habit as well. Interestingly enough, a universal AEB requirement on all vehicles would help in that scenario.

It's fair to say that some percentage of cases could be avoided by driving more defensively but I doubt it is significant. There are plenty of scenarios that the systems simply can't handle gracefully such as narrow or shifting lanes (my experience). The safest solution might be to avoid such roads entirely but then I'd never be able to leave my borough.

Road throughput is inversely proportional to following distance, so if everyone doubles their following distance to account for / avoid spurious automatic emergency braking, then we’d need to double the number of lanes to keep road capacity constant, which would lead to more lane changes, and therefore accidents.

If, instead, we kept the roads the same, then congestion would increase, and with it, accidents.

There is a reason that random unexpected emergency braking is a favorite tactic for people attempting to force accidents in order to commit insurance fraud: It’s too expensive for everyone to change their habits in order to guard against it.

If we care about reducing following distance, we should be lowering speed limits. A car doing 60 needs a much longer safer braking distance than one doing 45.

Also, if you are following at a distance where an AEB activation will cause you to rearend the vehicle in front of you, you are too close to safely follow any vehicle, regardless of whether it has an AEB.

Depending on where you live, if you leave a big gap someone else will just fill that space and you're back to the "short following distance" mode again. Rinse and repeat...

And then when the car in front has to tap the brakes for whatever reason, the tailgater has to slam them to avoid a collision, the person tailgating them also slams theirs, and you get a wave of braking propagating backwards, eventually creating a traffic jam.

I've had this happen too but after the first few times I understand why it's doing it and try not to follow too closely in these situations.

To be honest it sounds like you're making a damned good argument in favor of mandatory AEB. You're risking a collision because you assume that the car that's turning will behave in the way you expect it to behave (no judgement, I usually do it too). If you're wrong there's a high risk of a multi-car accident because naturally all the drivers in line behind you are tailgating.

I've detailed this in older comments, in a nutshell the first time was on a wet bridge where the car mistook the return of the bridge supports for an imminent crash causing the car to go into a spin (and on a narrow bridge that could have ended really badly, especially because of those supports). I had the car checked out and it was declared healthy, and that it must have been something spurious. A short while later it did it again, this time in a corner where an advertising sign was placed such that oncoming traffic could read it, again the car braked violently resulting causing some loss of control so it swerved into the oncoming lane. Fortunately no traffic there. I sold it right after and won't be buying another MB, ever. They've really lost the plot if they believe that this sort of thing is acceptable in a production vehicle for their regular clientele.

> The other comments here make ‘automatic emergency braking’ sound like a really good idea

That's because those other comments all assume that "automatic emergency braking" will only do exactly what it's supposed to do and will never make a mistake. But any sensible person knows that's not going to happen. These systems will make mistakes, and some of those mistakes will cause harm. So you can't just make a blanket claim that such systems are good. You have to actually look at the data and balance the harm they avoid by doing what they're supposed to do when they're supposed to do it, against the harm they cause when they make mistakes.

The obvious next question is, does the proposed rulemaking here consider the consequences of the system making mistakes? As far as I can tell, the answer is no, with just one qualifier. The claims about crashes prevented and lives saved are not net savings, accounting for harm done by the system making mistakes; those claimed numbers assume the systems will always perform perfectly and will never cause any harm, only prevent it. The one qualifier is that the proposal does include two "false positive" tests to try to spot systems that brake when they're not supposed to. But there is no analysis given to show why those particular false positive tests were picked or why they would justify the extremely high level of confidence in the systems not making errors that the rest of the proposal shows.

I think there is one other aspect to consider. Over here at least, generally if someone rear ends you it's always their fault. The law says they were not maintaining a safe following distance. So from the perspective of the manufacturer they would probably say such mistakes should not by themselves cause problems unless someone else is breaking the law, no different to a human tapping the brakes because they thought they saw a kid about to run on the road but it was just a jacket stuck on a tree.

You should be safe and free to brake without deep introspective thought, without fear of causing an accident. The real world is not that simple but that's how the law is generally setup.

And as a further point they'd probably say that if that person following had such a system, there's also less chance they'd rear-end you in turn. I was wary of the systems in my own car, but after 6 months of driving they are far more reliable than I'd feared and I'm quite impressed.

> from the perspective of the manufacturer they would probably say such mistakes should not by themselves cause problems unless someone else is breaking the law

The kinds of mistakes described elsewhere in this thread have not been of the form "system mistakenly brakes my car and someone behind me rear-ends me because they were following too close". So your comments, while valid for that particular scenario, do not appear to be relevant to what other posters are concerned about.

It's not only rear ending. The main road near my house has a sharp left turn with a sign on the side of the road. I occasionally get a BRAKE! warning there, probably because AEB mistakes that sign for a car in front of me. On a wet road, stepping on the brakes when the car is turning can easily result in understeer, which is particularly dangerous in that spot because of the large boulders nearby.

Yeah I was just adding to the things to consider. In my case it has never really confused inanimate objects, the worst was a curved road and a car coming "right at me" which was just at an angle. But it was a temporary slowdown due to cruise control, nothing major.

Car reviews are largely useless fluff - a real analysis of the differences between brands for this kind of thing could actually be useful.

That matches one of my two faulty EAB experiences nearly perfect.

I don't care if the law says the person who rear-ends me is technically at fault; I don't want to get rear-ended in the first place. If I can't control the driving of the car behind me, at least I'd like to be able to control my car to prevent the possibility of such a situation.

This is a solved engineering problem domain: use redundancy. There's a reason air travel is safe despite using many intricate safety technologies.

Redundancy doesn't work for design errors. You would need two diverse systems that have to agree before applying the brakes. This would also increase the "false negative" rate. It's a balance.

Why do you think these are design errors?

Not the poster

Vw golf r 2016 the sensor was low to the ground and it would randomly brake for stuff it thought was a threat like a cardboard box.

Subaru crosstrek 2018 - would brake for no reason, cars turning up ahead of me, etc.

VW atlas 2019 - brake for no reason would also scream at me and show a red symbol on the hud when nothing was in the road in front of me.

Subaru impreza 2023 - brakes for turning vehicles up the road, had it brake in a car wash.

On my vw vehicles i bought a can bus programmer so i could turn off as much if the safety stuff as possible because it made the car less safe to drive. In the impreza (current car) turning off the eyesight features is part of the pre-drive ritual.

I also had the lane assist on the crosstrek almost cause an accident on the highway at speed. Roads here are inconsistent and it was violently jerking the wheel trying to stay between lines.

Why not get a car without that stuff?

I got what was available at the time. The golf r is low production car finding one to buy was hard enough.

The crosstrek the only orange one available had eyesight.

The atlas was used so there was only 1 option locally

The impreza its standard on anything over base, and the base was missing other things i wanted.

Ok, that makes sense. I just bought a 1997 car and had it rebuilt, about 30% of the price of a new one and none of the crap, roughly just as safe as the current ones and much less likely to be stolen. Not the most economical decision because of course it is still a 1997 car but it will hold its value well enough that I'm not worried about it and I'm not really planning on selling it anyway. But if I ever do crash it then I'll probably lose a bunch of money because the present day value is less than what I put into it. Otoh just the write-off on a new one would have been roughly the total invested.

It's very frustrating how tech can be mis-applied. But I also see the regulators point of applied statistics and that even if these systems cause the occasional crash they prevent a much larger number from ever happening.

That's becoming increasingly harder as EuroNCAP mandates more and more of these as standard technologies that must be included. Manufacturers would much rather build one car and modify it as little as possible for all intended markets. So they design them with American and Chinese expectations for size, appearance, and features, and with European expectations for safety and emissions systems. We already can't buy new cars without rear cameras or forward emergency warning for that very reason.

> Subaru crosstrek 2018 - would brake for no reason, cars turning up ahead of me, etc.

Another anecdote - I have the exact same car and haven't had it do anything unexpected. It would really help if Subaru et. al. had ways to offer feedback back to them, because experiences like yours should be shared with them so they can understand what kind of corner cases some drivers are getting into.

> I also had the lane assist on the crosstrek almost cause an accident on the highway at speed. Roads here are inconsistent and it was violently jerking the wheel trying to stay between lines.

I've also not experienced this - the lane assist is just a nudge and if it's overpowering you you should take it to the dealership, this is not normal.

I have the same car and my experience matches yours. Lane assist is just a tiny nudge, and I've never had the emergency braking kick in. I wonder what causes the different behavior?

To be fair I was going 70mph at the time. It could be a small nudge but at 70mph feels worse. I also had only owned the crosstrek for about 5 minutes at that point and I couldn’t figure out how to turn it off as well, didn’t realize buttons were placed on the ceiling.

It was actually my first experience with the car, it happened on my way from the dealership to the office. It also didn’t help that I owneed the vehicle for 5 minutes at that point and could not find the button to disable it. I have since gotten rid of the car.

There is a hardware button on Subarus to disable EyeSight when you go through the car wash.

Anecdotal, but the alarm before the auto braking in my Crosstrek (2020) saved me two times. And I was in the car with a friend who activated the auto braking when they had just purchased it and weren't used to driving it.

Yeah its part of my pre-drive procedure since it happened. I’ve never had any of my vehicles auto brake in a way that was helpful.

Anecdotal, but I was riding with my friend on the highway (~70 mph) with absolutely nobody in front of us, and the automatic braking kicked in out of nowhere. Thankfully the one other person on the road that was a bit behind us swerved and avoided rear ending us.

After that experience, I don't want a vehicle with that functionality in it, and don't want other cars on the road having it. It's half-baked at best.

It had happened enough times to him, and he complained to the dealership enough, that they bought the vehicle back from him. Who knows if these incidents were ever reported to the NHTSA since no physical collisions with other cars occurred.

Make and model?

I know what it was, but I won’t participate in naming and shaming.

The dealership tried to fix it several times, and I don’t know if this is a systemic problem, or a single vehicle issue.

Either way, I don’t trust the tech. It can be developed and tested against plenty of different scenarios, but we live in a very uncontrolled and fluctuating environment.

I’ve had the automatic breaking in my Jeep take effect needlessly, which can be quite jarring

My Kia has AEB, Lane Keeping, and Adaptive Cruise Control. They have false positive type events from time to time, but generally you just know when it's going to happen. The first couple of times it was a shock, but I've never had it trigger in such a way that I felt like it would cause an accident. That being said, you can't just leave it un attended. You're still the PiC of the vehicle.

What it keeps doing to my wife is stopping the car (Audi) in oncoming traffic when she is making a left turn from a median across a road that is two lanes in each direction. She is basically jamming the accelerator to go, and so it applies the brakes for a very hard stop, which once resulted in the car behind her not being able to stop.

Reply on news.ycombinator.com