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Rear ended another vehicle, not blaming Tesla but wondering why AEB did not activate?

WilliamG

Active Member
Apr 20, 2019
3,024
2,919
Seattle, WA
AEB won't kick in if your using AP or TACC and accelerating. A warning comes up that it is not available under those conditions.

Don't think that's true. The only message I've seen is that it won't maintain the speed you set AP to because you're accelerating. There's no mention of AEB not working that I've seen.
 

scottf200

Active Member
Feb 3, 2013
3,770
3,326
Chicagoland ModelX S603
It's a a good demonstration that it probably makes sense to have TACC on even if not using autosteer. That would save a lot of grief here.
My answer to that would be categorically “no”. There is, however, a huge amount of speculation online.
My guess would be “yes”. But I could be wrong.
Yes. I experienced about 1 week ago. I was driving 30ish (no-AP or TACC) in the left lane of a 4 lane suburban road and the car in front of me slowed some and then brakes fairly hard to make a U-turn. I was looking forward and saw them but my years of experience told me that they would be out of the way by the time I got close enough (or I'd have time to brake myself). AEB kicked on *with* my foot on the accelerator. First I experienced that. I'm often in AP on suburban roads even.
 
  • Informative
Reactions: KenC

Mojito

Member
Apr 16, 2019
117
37
Orlando
I have had something similar where i was wondering why my car auto brake as the car in front was just switching lane to the left when the warning beeps came on and i realized the cars in front of the car switching lane where stopped. So the radar anticipated the problem.
 

M109Rider

Active Member
Apr 8, 2018
1,489
1,518
Kitchener, Ontario
Hi all,
I recently rear ended someone and when it happened my EAB made no attempt at stopping the vehicle. Long story short- I was merging on the highway, I looked over my shoulder, and started to merge- traffic was moving fine but as I turned my head back around my lane came to a stop and I rear ended this woman.

Before people start commenting saying I’m a terrible driver and inform me how it’s not Tesla’s job to stop you, blah blah blah, I’m not looking for that. I am NOT blaming my car for anything and I am not stating it should have made everything all better- I am just curious why EAB didn’t kick in at all. Video below.


2019-11-08_08-16-11-front.mp4

I think many here have helped answer your questions already.
Sorry for your accident. Glad your not hurt.

I think everyone here would be devastated if we crashed our cars.
I hope you get things fixed soon, and can put this all behind you.
 
Last edited:
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Tam

Well-Known Member
Nov 25, 2012
8,261
7,114
Visalia, CA
...curious why EAB didn’t kick in at all...

My guess is the technology is not matured enough for AEB to consistently work even when a driver can replicate the laboratory conditions.

Audio recordings might be helpful because there might be audio alerts that you might not notice until reviewing it.

The car in front is not exactly centered. That is not even a good replication for laboratory conditions!

Autopilot (which is not in this case) has numerous cases where it hits a car that is off-centered.

If AEB kicks in, it would be the very last second which would not prevent a collision but to lessen the speed to reduce the force of the collision. It's possible that in this case, you didn't allow the system to do that (a collision at the last second, even with a lesser speed) as you might have manually steered or applied the brakes.

This will have to get better because Robotaxis without any human drivers cannot operate like this.

In the meantime, the system is still using radar which is an imperfect technology since 1935 (talking about still immatured radar technology after 84 years!)

Hopefully, Tesla Vision which might eliminate this problem soon (Here we go for another 84 years to catch up with radar maturity).
 

KenC

Active Member
Sep 4, 2018
3,278
2,993
Maine
Sorry about your accident. Some good comments already, but the one thing I wanted to add is that the Subaru had a brake light that was out, the left one. I wonder if that had an effect.
 
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MrG_NY

Member
May 20, 2019
139
102
NY
Don't think that's true. The only message I've seen is that it won't maintain the speed you set AP to because you're accelerating. There's no mention of AEB not working that I've seen.
I may have misread the warning. But I swear thats what it has said a few times.
 

alsetym

Member
Apr 28, 2018
254
276
hamilton
In most (not all) cars the AEB has a high bar for activation and applies the minimal amount of brakes require to reduce likelihood of injury. This impact was pretty minor, thankfully, with very low liklihood of injury. The car may have braked slightly, or, more likely the anticipated accident did not meet its threshold for activation. You don't necessarily want cars throwing out the anchors on every impact, at least not until it is basically perfect. I believe volvo and some others have a lower threshold, I'm sure tesla will someday as well. Unfortunately Tesla spends most of their time making sure AP doesn't hit things and their passive systems are not leading edge (except the accident avoidance stuff which is nifty but very limited in operational domain)
 

donlchau

Member
Jul 5, 2017
22
0
Los Angeles
It is a bummer what happened to your car.

AEB is not designed to work if you are not established in a lane and if the wheel is being turned sharply. If you had merged over and was slowly cruising forward, the AEB would have kicked in. In the video, it appears you were not established in the lane and was in the process of moving over to another lane.

Even if you tried, AP would not have even worked since lanes were not established in your particular incident. I hope insurance doesn't cause too much of a headache for you.
 

PaulS

Member
Jun 14, 2016
71
39
Whistler, BC
Hi all,
I recently rear ended someone and when it happened my EAB made no attempt at stopping the vehicle. Long story short- I was merging on the highway, I looked over my shoulder, and started to merge- traffic was moving fine but as I turned my head back around my lane came to a stop and I rear ended this woman.

Before people start commenting saying I’m a terrible driver and inform me how it’s not Tesla’s job to stop you, blah blah blah, I’m not looking for that. I am NOT blaming my car for anything and I am not stating it should have made everything all better- I am just curious why EAB didn’t kick in at all. Video below.


2019-11-08_08-16-11-front.mp4

Sorry to hear that!... I recently had a similar accident. Merging just like you were, through it was a double lane of merging and an SUV cut me off moving right to left across the two merge lands and then slammed on the brakes and I didn't manage to get stopped. AP, nor TACC, were on. The AEB warning and sound flashed, I also tried to swerve and hit the brakes and I just failed to stop short. Worst part of it was that the first thing the driver of the SUV said was "I thought Tesla's can't have accidents"... I took a very deep breath and politely said, "well, there are limits to how fast a heavy car can stop". Side note... it could have been my shoulder check that cost me the time needed to react quickly enough, or it could have been a glance to the nav system display to the left of the steering wheel that took my focus off the action directly in front of me. It is disappointing that a car with so much capability couldn't avoid this low speed accident, though I appreciate that collision avoidance tech is nowhere near perfect and it may be impossible for it to ever become completely perfect. After analyzing the event in my head for a couple days, I accepted what happened, chalked it up to a hard lesson learned, and moved on... painful as the experience, expenses, and 2 months without my car were.
 

Knightshade

Well-Known Member
Jul 31, 2017
11,150
14,458
NC
Don't think that's true. The only message I've seen is that it won't maintain the speed you set AP to because you're accelerating. There's no mention of AEB not working that I've seen.


It does mentions autopilot will not brake while you're pressing the accelerator.

That's not the same thing as AEB of course
 

newsletter

Member
Oct 15, 2019
8
1
Toronto
It's interesting that AEB will not kick in if your foot is on the accelerator. Does it matter how much distance the accelerator is being depressed? If the driver's foot is off the accelerator, and they're not in TACC or Autopilot, then the driver's intention would be regening or braking so they are planning to slow down anyway. So AEB is really just assisting you to brake harder or faster?

EDIT: From above posts, it sounds like AEB is always active even when accelerator is pressed down.
 
  • Disagree
Reactions: glide

MXWing

Well-Known Member
Oct 13, 2016
7,270
17,738
USA
Here's a thought:

What if there was a setting to default distance between cars above a certain speed? Not quite cruise control but like TABS
"Tesla Anticipatory Braking System" as it can be toggled on and is independent of cruising speeds.
 

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