AEB is too abrupt - I got rear-ended

[GtiMart]

OP, I agree. I had a similar incident yesterday. In traffic, car in front stopped hard. I was checking behind me so i wouldn't get rear ended and braking just enough to not hit the car in front. I was planning to leave like a foot, as there was no room to pass on either side (road works, concrete barriers). The car decided I wouldn't brake and did it for me. Didn't like it. Good thing the person behind was paying attention.

Now, I still leave AEB on in case it saves me one day but that event wasn't good. The thing is, not many drivers are "good enough" to stop a foot away and not panic so I understand why it did what it did. It's just frightening.

 

[GoodbyeICE]

I’ve had AEB trigger a few months ago, the only time it ever has since getting my M3P. It surprised me completely as IMO there wasn’t any reason for it to be applied. There was plenty of room in front of me (car in front had not even stopped yet) but it shocked me and I even considered scheduling a service appointment. Hasn’t happened since but had someone been following closely behind me I imagine they may have rear-ended me.

 

[Null860]

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.

You'll want that 5-10 ft in front of you if the car behind hits you at higher speed.

In my 2016 Volt (rip) stopped for traffic (quickly) bit no squealing, not panic.. left about 10 ft. Hit was from behind but civic was going like 30 when it hit...
Serious concussion... 4 months out of work...

Wish I had left 20 ft

 

[jrmt23]

Happened to me in my VW.

Jeep in front of me suddenly braked on the freeway, AEB alerted and slammed on the brakes. The person behind me was too close and rear ended me. Guess it's a good lesson to not tailgate people . Getting hit myself still sucks, but I'm just glad I didn't hit the person in front of me. Other person's insurance took care of my car's repairs.

 

[Paddy3101]

My view, is that AEB kicks in "When a collision is inevitable", and it will always, brake as hard as it can to 'mitigate' the inevitable collision.

So, by the time AEB kicks in, the car/driver is already in minimize injury/damage mode, specifically from hitting the car/object in front. It's not a 'controlled' stop situation, its already a brake, and hope situation. It's way past the collision warning situation.

Sometimes, it will be able to brake, and stop before the collision, some times it won't be able to. In this case, the car was lucky.

To the OP:
At 30mph, 5 feet equates to 113milliseconds. So, you was 0.1second from the collision when the car braked as hard as it could, because you wasn't braking. At that point, it would have taken you more than 0.1 second to press the brake peddle , even ignoring any reaction time.

Minimum reaction time, when you are anticipating an event, (with the right type of event - e.g. starting pistol) is 100ms. So, it was already too late, for any human to react, when the AEB activated.

 

[richrootes]

What a weird thread. Post the videos from the incident then we can all draw some evidence based conclusions

 

[dfwatt]

What a weird thread. Post the videos from the incident then we can all draw some evidence based conclusions

Here's your evidence-based conclusion: when AEB kicks in, it either means you're following too closely or you're not paying attention.

 

[pl8dlikafiddle]

Wait - so the car’s safety feature worked as intended (stopped within 5-10’ of cars in front), you get rear ended because person behind you did not react in time or was following too close, and it is Tesla’s fault the AEB is too aggressive?

Here’s a thought - pay attention and don’t let AEB kick in. Even better, turn it off since apparently you can do better than a 5’ gap.

If it didn’t activate or the alarm didn’t go off, you’d be here complaining it didn’t work because your front end is bashed in.

 

[pipp]

The manual says that the AEB system is not designed to prevent collisions, but “at best” to minimize the impact of a frontal collision. So either the car is not working as designed, or the manual needs to be re-written.

 

[Gasaraki]

OP, I agree. I had a similar incident yesterday. In traffic, car in front stopped hard. I was checking behind me so i wouldn't get rear ended and braking just enough to not hit the car in front. I was planning to leave like a foot, as there was no room to pass on either side (road works, concrete barriers). The car decided I wouldn't brake and did it for me. Didn't like it. Good thing the person behind was paying attention.

Now, I still leave AEB on in case it saves me one day but that event wasn't good. The thing is, not many drivers are "good enough" to stop a foot away and not panic so I understand why it did what it did. It's just frightening.

I don't get why people drive like this. Stop looking back "so I wouldn't get rear ended". Look forward. Whatever happens behind you is up to the person behind you. If you're trying to leave "a foot" of space in front of you and the person behind you still hit you, you'll get pushed in to the vehicle in front of you. And you know what, it will be your fault you hit the car in front of you even though you got pushed in. Drivers ed says to leave enough room in front of you, NOT "look back and make your the person behind you enough room also". If everyone followed that training then you wouldn't even need to "look back", because they would be far enough from your back.

If you have your seatbelt on, get hit from the back is better than getting hit from the back and then getting rammed in to the car in front of you.

This is exactly what happened to my cousin.


Another stupid driver story related to this:
I'm traveling 65mph on a two lane road. A girl pulls out in front of me from a driveway, I see her and begin to slowly slow down, no need to slam on the brakes. So I quickly approach her back but obviously not going to hit her. You know what she did?!? She swerves on to the oncoming traffic lane thinking i was going to hit her or something. MY MIND WAS BLOWN. I have never seen this in my life. You know how you avoid people approaching you from your back? You hit the accelerator pedal and reach the travel speed as soon as possible, not putt along at 35 mph on a 65 mph road. Pay attention to your own driving, stop looking back and try to predict something that might happen behind you.

 

[dfwatt]

The manual says that the AEB system is not designed to prevent collisions, but “at best” to minimize the impact of a frontal collision. So either the car is not working as designed, or the manual needs to be re-written.

Good example of under-promise and over-deliver. Most manufacturers do not claim to prevent accidents with automatic emergency braking. In the independent testing that's been done of these systems Tesla's is consistently among the best and does a better job than most in preventing collisions.

 

[GtiMart]

@Gasaraki, thanks for your concern. I drive farther away from the car in front, don't worry. Sometimes people brake hard in front of you. Since I'm far away, I have time to react and stop much farther than one foot. Heck, I even have time to look backwards. I can use that time to adjust my braking distance to give a chance to the car behind that might not have been so careful. Saving an accident, repairs etc is important to me so I do this type of thing. I drive as if everyone on the road was out to get me, I "drive for others". This has saved me in more than one occasion. I won't stop assuming people around me cannot drive because you say so

 

[Ren.OG]

Drivers ed says to leave enough room in front of you, NOT "look back and make your the person behind you enough room also".

Whats if its an 18-wheeler Semi/Lori coming at you at 60MPH?
Gunna sit in your lane and let it happen?

I've been in 4 accidents, getting rear-ended at stop lights/traffic, people running stop signs/stop lights.
I've avoided 200 accidents by being aware of what's going on behind me and having an escape route.
I once dodged a car behind me by swerving into the shoulder, he almost hit the car that was in-front of me.

Situational awareness is needed out on the roads.

If you love insurance claims and whiplash please don't listen to me.

 

[Gasaraki]

I won't stop assuming people around me cannot drive because you say so

I think you do assume others can't drive because you think that if you don't do the thing you now, other people would be hitting you left and right.

 

[Gasaraki]

Whats if its an 18-wheeler Semi/Lori coming at you at 60MPH?
Gunna sit in your lane and let it happen?

I've been in 4 accidents, getting rear-ended at stop lights/traffic, people running stop signs/stop lights.
I've avoided 200 accidents by being aware of what's going on behind me and having an escape route.
I once dodged a car behind me by swerving into the shoulder, he almost hit the car that was in-front of me.

Situational awareness is needed out on the roads.

If you love insurance claims and whiplash please don't listen to me.

I get it but that's situational awareness, not "let me brake later so I can leave less room for myself and more room for them".

 

[pipp]

Good example of under-promise and over-deliver. Most manufacturers do not claim to prevent accidents with automatic emergency braking. In the independent testing that's been done of these systems Tesla's is consistently among the best and does a better job than most in preventing collisions.

“Over-deliver”? At what point does the “over-deliver” become “endanger”? When the AEB forces a stop 10-feet before a collision? 20 feet? 50 yards? Whatever the distance, document it accurately and spare people the “over-delivery”.

 

[Paddy3101]

“Over-deliver”? At what point does the “over-deliver” become “endanger”? When the AEB forces a stop 10-feet before a collision? 20 feet? 50 yards? Whatever the distance, document it accurately and spare people the “over-delivery”.

What was the rate the truck in front slowing? Is it constant, will it hit something in front, increasing it's deceleration, will its brakes fade, will is skid loosing traction....
What surface was the road at that particular braking zone.
What was the camber of the road.
What was the temperature of the road.
What was the temperature of the tires.
What is the tread depth of the tires.
What is the condition of the tires.
What is the traction rating of the tires.
What was the temperature of the brakes.
What was the roughness of the road.
Was the surface on the left side of the car the same as the right side.
Was there any moisture on the road.
What was the gradient of the road.
Was there any loose material on the road.
Is the road 100% smooth, or are there any lumps/pits.
What is the COF for the brake pads, and brake disks, right now.
What hydraulic pressure do I need to effect the needed stopping force.
What is the efficiency curve of the brake booster for the needed pressure.

Now, put all of that information, for that particular 45feet of into a model of the car's dynamics, and solve that to give the exact braking effort. Do that 100times per second.

No....

Or make lots of assumptions about lots of that, and err a % on the safe side so that the car makes a good call, most of the time, so that most of the time, in most situations, the outcome is better than had it not intervened.

The Car isn't Omnipotent.

 

[KenC]

I don't get why people drive like this. Stop looking back "so I wouldn't get rear ended". Look forward. Whatever happens behind you is up to the person behind you. If you're trying to leave "a foot" of space in front of you and the person behind you still hit you, you'll get pushed in to the vehicle in front of you. And you know what, it will be your fault you hit the car in front of you even though you got pushed in. Drivers ed says to leave enough room in front of you, NOT "look back and make your the person behind you enough room also". If everyone followed that training then you wouldn't even need to "look back", because they would be far enough from your back.

If you have your seatbelt on, get hit from the back is better than getting hit from the back and then getting rammed in to the car in front of you.

This is exactly what happened to my cousin.

Another stupid driver story related to this:
I'm traveling 65mph on a two lane road. A girl pulls out in front of me from a driveway, I see her and begin to slowly slow down, no need to slam on the brakes. So I quickly approach her back but obviously not going to hit her. You know what she did?!? She swerves on to the oncoming traffic lane thinking i was going to hit her or something. MY MIND WAS BLOWN. I have never seen this in my life. You know how you avoid people approaching you from your back? You hit the accelerator pedal and reach the travel speed as soon as possible, not putt along at 35 mph on a 65 mph road. Pay attention to your own driving, stop looking back and try to predict something that might happen behind you.

People want to avoid all collisions, forward and rear. You would only check the rear, once you had made sure you were clear in front.

People are trying to avoid the accident where you stop 10ft short, and the person behind hits you, but if you had checked, and been able to give the person behind, another 5ft, they could have stopped without hitting you. Why not try to avoid that?

Also, it's NEVER your fault if the driver behind hits you and pushes you into the car ahead. With a Tesla, you want to avoid any and all collisions, given how long body work repairs can take.

 

[Paddy3101]

People want to avoid all collisions, forward and rear. You would only check the rear, once you had made sure you were clear in front.

People are trying to avoid the accident where you stop 10ft short, and the person behind hits you, but if you had checked, and been able to give the person behind, another 5ft, they could have stopped without hitting you. Why not try to avoid that?

Also, it's NEVER your fault if the driver behind hits you and pushes you into the car ahead. With a Tesla, you want to avoid any and all collisions, given how long body work repairs can take.

You can do exactly that. The car's not stopping you, just get to nearly stopped, and then accelerate the last 5 feet to close up the 'gap' you feel you need.

Almost certainly won't happen for the average, or probably even most experienced drivers, in most cases where AEB kicked in. You'll most likely be already stopped by the time you get to look in the mirror.

In general people just don't react that quickly, unless they already have that planned out ahead of time; in which case AEB wouldn't be an issue in the first place.

 

[pipp]

What was the rate the truck in front slowing? Is it constant, will it hit something in front, increasing it's deceleration, will its brakes fade, will is skid loosing traction....
What surface was the road at that particular braking zone.
What was the camber of the road.
What was the temperature of the road.
What was the temperature of the tires.
What is the tread depth of the tires.
What is the condition of the tires.
What is the traction rating of the tires.
What was the temperature of the brakes.
What was the roughness of the road.
Was the surface on the left side of the car the same as the right side.
Was there any moisture on the road.
What was the gradient of the road.
Was there any loose material on the road.
Is the road 100% smooth, or are there any lumps/pits.
What is the COF for the brake pads, and brake disks, right now.
What hydraulic pressure do I need to effect the needed stopping force.
What is the efficiency curve of the brake booster for the needed pressure.

Now, put all of that information, for that particular 45feet of into a model of the car's dynamics, and solve that to give the exact braking effort. Do that 100times per second.

No....

Or make lots of assumptions about lots of that, and err a % on the safe side so that the car makes a good call, most of the time, so that most of the time, in most situations, the outcome is better than had it not intervened.

The Car isn't Omnipotent.

The logic being, “the car isn’t omnipotent, so providing bogus documentation about the car is therefore justified”?