AEB is too abrupt - I got rear-ended

[M32021]

I was driving my Model 3 yesterday when the tuick in front of me slammed on their brakes. I was going about 30 MPH at the time and AEB kicked in (sound, screen alert) and hard braking. The car broke so hard that the driver behind me did not have a chance to react and they hit me. Yes, it is their fault. However, if AEB had not taken over, I would have been able to leave more room between me and the truck in front of me. I actually had about 5-10 feet in front of me still. The AEB simply applied the brakes too hard. I read lots of other posts on this site and others about this concern. I am going to report this to Tesla when I have them inspect the car. I am also changing the Forward Collision Warning setting to "late" instead of the current default of "medium."

For the record, I love this car and it is by far this is the best car I have ever owned. But AEB can be improved and I have read complaints/concerns that span years now, and nothing seems to have improved in the software.

 

[ianc]

The car does not have precise knowledge of the surface it's on or what kind of braking power it can generate, so it does the best it can. Quibble over 5 ft? Just be thankful you didn't hit the car in front of you and it's not your fault...

 

[dfwatt]

I was driving my Model 3 yesterday when the tuick in front of me slammed on their brakes. I was going about 30 MPH at the time and AEB kicked in (sound, screen alert) and hard braking. The car broke so hard that the driver behind me did not have a chance to react and they hit me. Yes, it is their fault. However, if AEB had not taken over, I would have been able to leave more room between me and the truck in front of me. I actually had about 5-10 feet in front of me still. The AEB simply applied the brakes too hard. I read lots of other posts on this site and others about this concern. I am going to report this to Tesla when I have them inspect the car. I am also changing the Forward Collision Warning setting to "late" instead of the current default of "medium."

For the record, I love this car and it is by far this is the best car I have ever owned. But AEB can be improved and I have read complaints/concerns that span years now, and nothing seems to have improved in the software.

I think you're assuming a lot. First of all you're assuming that there was in fact way to avoid the front Collision without getting rear-ended. Many times that is physically impossible. You can either hit the car in front of you or you can be rear-ended but you can't avoid being rear-ended and additionally if you hit the car in front of you you're probably going to be rear-ended to in that scenario anyway. Additionally my experience with automatic emergency braking suggests that it actually titrates its level of braking Force better than most humans could do in a panic stop situation. It applies just enough Braking to maintain your following interval if that's possible. If it is not possible to maintain the following interval this essentially means that there is no way you could have avoided the second Collision when somebody following you too closely rear-ends you. As for all the complaints that you've heard about automatic emergency braking online most of them are actually around Phantom braking in autopilot. There are not that many complaints about aeb. Lastly, changing the forward Collision warning system too late will not affect its emergency braking Behavior. Also if you needed emergency braking application to avoid hitting a truck in front of you it sounds like you were following too closely. Trucks can't stop very fast by definition. AEB actually appears to have bailed you out from a much more expensive and punitive situation where you would have rear-ended the truck. You would have been clearly at fault for that. So rather than blaming Tesla maybe you should change your behavior.

 

[Ren.OG]

I somewhat agree with OP.

I don't use 'Autopilot' while in heavy traffic because of this reason, too much stop-n-go. The car tries too hard to keep that 'perfect' distance between you and the car ahead and the result is jerky acceleration and sudden brake stomps. (Chill mode and sport steering helps, can't set braking power tho)
I feared for my rear-end the few times i used Autopilot in traffic, anxiety couldn't have been higher. People are not paying attention out there, a sudden slap of the brakes while still having 10ft of space ahead of you can definitely catch the driver behind off-guard.

In retrospect dfwatt has a point, you could have potentially been pushed into the truck in front of you if you allowed for that extra 5ft of space that AEB did not.
Insurance is a headache but being at fault is even worse.

 

[M32021]

A few clarifications that I should add. I do not have FSD (just auto-pilot that came standard). I was not using the cruise control or lane control at the time of the accident. AEB kicked in as part of forward collision prevention. And luckily, even though I was rear-ended, there was minimal damage to either car bc we were both going very slow at the moment of impact.

But my whole point in sharing this was that I could have prevented the accident from happening if I could have prevented the Tesla from braking so hard... That is why I mentioned the 5-10 ft of space in between me and the truck. I would have used that space to create extra buffer in between all 3 cars. AEB just locks the brakes.

I am a hughe proponent of FSD in the future and I want Tesla (and all cars) to succeed in this... However, from my 6 months in the model 3, I can see that FSD has a long way to go! And in my 30+ years of driving, I have never rear ended another car and never been rear ended. Until now. And as much a it pains me to say it, AEB was part of the cause. I do feel safer knowing that AEB will prevent me from hitting someone else, but I fear those behind me! Even more than before.

 

[dfwatt]

A few clarifications that I should add. I do not have FSD (just auto-pilot that came standard). I was not using the cruise control or lane control at the time of the accident. AEB kicked in as part of forward collision prevention. And luckily, even though I was rear-ended, there was minimal damage to either car bc we were both going very slow at the moment of impact.

But my whole point in sharing this was that I could have prevented the accident from happening if I could have prevented the Tesla from braking so hard... That is why I mentioned the 5-10 ft of space in between me and the truck. I would have used that space to create extra buffer in between all 3 cars. AEB just locks the brakes.

I am a hughe proponent of FSD in the future and I want Tesla (and all cars) to succeed in this... However, from my 6 months in the model 3, I can see that FSD has a long way to go! And in my 30+ years of driving, I have never rear ended another car and never been rear ended. Until now. And as much a it pains me to say it, AEB was part of the cause. I do feel safer knowing that AEB will prevent me from hitting someone else, but I fear those behind me! Even more than before.

I appreciate that you're trying to buff up your post. You don't need any version of automatic or for that matter any version of regular emergency braking unless you are following too closely. We have a culture in this country of Relentless tailgating. It infects everybody, even otherwise responsible drivers and people. This is a good example of why it's a bad idea. You caught a break. I hope you learned your lesson. Expecting the technology to be perfect so that you can continue what is a fundamentally bad practice is unfortunately a popular idea, but it's better to change our Behavior. I speak from experience as I used to be somebody rushing around trying to get the extra 10th. I just don't do that anymore because it's not worth it.

 

[MP3Mike]

But my whole point in sharing this was that I could have prevented the accident from happening if I could have prevented the Tesla from braking so hard...

You don't know that. Your reaction would have been, and actually was, slower than AEBs which likely would have delayed when the person behind you started braking. The most likely outcome if AEB was turned off and you closed the gap to the truck in front of you would have been that you still would have been rear ended and pushed into the truck. (At which point you would have been assumed to be at fault for that, unless you could prove you were pushed into the truck.)

And BTW, changing the Forward Collision Warning to late doesn't change anything about when AEB will trigger. It only controls when it will set off the alerts in the car to try to get your attention. AEB used to only intervene when its calculations showed that a collision was unavoidable. Obviously they have made it a little more aggressive now, in that it can prevent a collision.

 

[PDX-Y]

I actually had about 5-10 feet in front of me still.

You're asking for too much. If the car behind you hit you despite you having stopped only half a car length behind another car, then that was not a feasibly avoidable collision for any system, human or machine. Assuming you saw damage, that means the car behind you was going 20 mph+ at the moment of collision. Nothing stops in 15' from 20mph.

 

[Vines]

I go back and forth with AEB for just this reason. Several times it has activated too strongly, and I have nearly gotten hit. OTOH, if someone rear-ends me it's usually their fault, and my trying to close the gap could likely lead to my being at fault as well.

Also, if you try to override the AEB, only a soft throttle depress, or a tap of the brakes will take it out of AEB mode, so you can get your car moving and out of danger. Of the 2 times I have had the mental bandwidth to accelerate to escape the AEB full stop and prevent a rear end collision I haven't really gotten the response I was hoping for either time. I understand I pressed the throttle too strongly/quickly.

 

[PDX-Y]

I go back and forth with AEB for just this reason.

I've yet to see it engage in 3000 miles of driving. I've seen a few warnings, but no braking. How often are you having to go "back and forth" on this system, and where are you driving?!

 

[Vines]

When I say back and forth, I mean I briefly turn it off because I lack confidence in it being safer, then turn it back on for safety.

I drive all over and just completed a 10k road trip across the country.

 

[brkaus]

I had AEB save me last week. A truck stopped several cars ahead around a corner. I started to brake but aeb kicked in harder. It did stop with about 10ft between me and the next car.

truck coming in behind me didn’t see the mess and was able to get the the center turn lane before hitting me. I did briefly hit the go pedal to move up an extra 5ft once I saw him in the rear view.

 

[KenC]

I was driving my Model 3 yesterday when the tuick in front of me slammed on their brakes. I was going about 30 MPH at the time and AEB kicked in (sound, screen alert) and hard braking. The car broke so hard that the driver behind me did not have a chance to react and they hit me. Yes, it is their fault. However, if AEB had not taken over, I would have been able to leave more room between me and the truck in front of me. I actually had about 5-10 feet in front of me still. The AEB simply applied the brakes too hard. I read lots of other posts on this site and others about this concern. I am going to report this to Tesla when I have them inspect the car. I am also changing the Forward Collision Warning setting to "late" instead of the current default of "medium."

For the record, I love this car and it is by far this is the best car I have ever owned. But AEB can be improved and I have read complaints/concerns that span years now, and nothing seems to have improved in the software.

I first thought this was trolling, but apparently not. I have a feeling, you can mitigate the strong braking effect of AEB, by pressing lightly on the throttle pedal, so you can close the gap to the vehicle ahead and possibly prevent the car behind from piling into you.

Not only should you be prepared to close the gap in front of you, you should consider a bailout lane, if you think there's a vehicle behind you, closing in on you. I've always assumed my vehicles would stop faster, since, I drive cars with good tires, and most vehicles around me are driving heavier SUVs or trucks with average tires, so always be prepared.

 

[PDX-Y]

you should consider a bailout lane

Please never do this. Getting rear ended straight on in a travel lane, even at high speed, is a survivable accident in almost all cases. Swerving is how you roll over and die. Remember the circumstance here is that AEB engaged, which means by definition the driver was not aware enough to have stopped in time to avoid the car ahead. It strains reason to argue the driver is going to be reliably aware of a gap in a lane to the side. Don't. Never swerve.

 

[KenC]

Please never do this. Getting rear ended straight on in a travel lane, even at high speed, is a survivable accident in almost all cases. Swerving is how you roll over and die. Remember the circumstance here is that AEB engaged, which means by definition the driver was not aware enough to have stopped in time to avoid the car ahead. It strains reason to argue the driver is going to be reliably aware of a gap in a lane to the side. Don't. Never swerve.

uhm, sure.

 

[Vines]

Please never do this. Getting rear ended straight on in a travel lane, even at high speed, is a survivable accident in almost all cases. Swerving is how you roll over and die. Remember the circumstance here is that AEB engaged, which means by definition the driver was not aware enough to have stopped in time to avoid the car ahead. It strains reason to argue the driver is going to be reliably aware of a gap in a lane to the side. Don't. Never swerve.

My first road trip up my old stomping grounds in Washington, Longview area and about 12 hours in the traffic comes to a halt in Portland.

I was in autopilot at the time, and eating a tamale. When I felt AP strongly brake, that was my cue to put the food down. As I am looking behind me to see whats up a massive Chevy with an even larger steel bash bar is barreling at my bumper, not slowing at all. This was part of the freeway where it was all paved and just barely 1 can can squeeze between the wall and the fast lane.

As I am taking control I make the swift decision to swerve into the emergency lane with about 15-25 feet to the bumper of the car in front of me. At this point I am looking both forward and backwards, and I see the Chevy truck notice his error and follow me into the left emergency lane with a screech of brakes.

He ends up 2.5 cars past where it was safe to stop, probably noticed the stop going about 50 mph. I can't imagine what went through the minds of the 3 drivers we passed.

I strongly disagree that swerving is not a valid strategy, just don't lose control.

 

[dhrivnak]

A few clarifications that I should add. I do not have FSD (just auto-pilot that came standard). I was not using the cruise control or lane control at the time of the accident. AEB kicked in as part of forward collision prevention. And luckily, even though I was rear-ended, there was minimal damage to either car bc we were both going very slow at the moment of impact.

But my whole point in sharing this was that I could have prevented the accident from happening if I could have prevented the Tesla from braking so hard... That is why I mentioned the 5-10 ft of space in between me and the truck. I would have used that space to create extra buffer in between all 3 cars. AEB just locks the brakes.

I am a hughe proponent of FSD in the future and I want Tesla (and all cars) to succeed in this... However, from my 6 months in the model 3, I can see that FSD has a long way to go! And in my 30+ years of driving, I have never rear ended another car and never been rear ended. Until now. And as much a it pains me to say it, AEB was part of the cause. I do feel safer knowing that AEB will prevent me from hitting someone else, but I fear those behind me! Even more than before.

One is able to set the sensitivity and or turn off forward braking if you want.

 

[oreobbq]

My first road trip up my old stomping grounds in Washington, Longview area and about 12 hours in the traffic comes to a halt in Portland.

I was in autopilot at the time, and eating a tamale. When I felt AP strongly brake, that was my cue to put the food down. As I am looking behind me to see whats up a massive Chevy with an even larger steel bash bar is barreling at my bumper, not slowing at all. This was part of the freeway where it was all paved and just barely 1 can can squeeze between the wall and the fast lane.

As I am taking control I make the swift decision to swerve into the emergency lane with about 15-25 feet to the bumper of the car in front of me. At this point I am looking both forward and backwards, and I see the Chevy truck notice his error and follow me into the left emergency lane with a screech of brakes.

He ends up 2.5 cars past where it was safe to stop, probably noticed the stop going about 50 mph. I can't imagine what went through the minds of the 3 drivers we passed.

I strongly disagree that swerving is not a valid strategy, just don't lose control.

With the way I eat tamales, everything within a 3 foot vicinity ends up greasy. Either your car is gross or maybe you got next level tamale skills.

But yeah at reasonable speeds I don't see anything wrong with using the emergency lane cautiously when needed.

 

[techlogik]

Is this a vision only car? Not surprised. It’s ability to determine distance is garbage. Tesla knows it. Covered enough already about how ACC will only let you go to 3 and trail far back, but even then it will sometimes follow close. Inconsistent. Also, AEB is another disaster on vision only. Sidebar like Tesla reads or cares about this stuff, they need to stop rolling out Disney and game updates and fix real issues as promised.

With that said, driver behind is at fault obviously. Insurance and police will agree. Be thankful you didn’t hit the car in front unless the person behind you pushed you into them.

 

[KenC]

Please never do this. Getting rear ended straight on in a travel lane, even at high speed, is a survivable accident in almost all cases. Swerving is how you roll over and die. Remember the circumstance here is that AEB engaged, which means by definition the driver was not aware enough to have stopped in time to avoid the car ahead. It strains reason to argue the driver is going to be reliably aware of a gap in a lane to the side. Don't. Never swerve.

One, the OP says this AEB took place at 30mph. Not "high speed".

Second, my sister, a pediatrician, and I were just talking about one of her college-aged patients who is now a quadriplegic, after being rear-ended, in Denver. The same location as the OP. Rear-end collisions are often "survivable", but the injuries can be tragically catastrophic.

Third, how often does swerving into the lane beside you, or the breakdown lane, result in a "roll over and die" accident? At 30mph?!? In a low CoG vehicle like a Tesla?

Fourth, what is with your "by definition"?!? The driver ended up 10ft short, he might have braked in time. He might also have been driving next to a breakdown lane. Swerving out of the lane, takes LESS time than it takes to emergency brake to a complete stop. When a collision may seem unavoidable via emergency braking, it might be avoided by a quick turn of the wheel.