WARNING: I rear-ended someone today while using Auto Pilot in my brand new P90D!

[Krugerrand]

Thank you Brent, you may not often post but when you do...!

I will certainly consider using the TACC at setting 7 after reading this and thinking deeply about it (once I get my car that is).
In my experience people will try to cut in front of you no matter how big a gap you leave, so best to have te room to react than to try and dissuade them with smaller gaps.

Brent's post was great. So many people in a hurry to go nowhere. If it's that important for someone to get a few feet closer to their destination, have at it I say. For sure I won't be the one on the side of the road collecting or giving insurance information.

 

[McRat]

I feel for the OP. That must have been very embarrassing and quite a hassle. Glad everyone is OK. I'm not so quick to blame the car mfr though. The following is not going to be popular, but is true:

Even if cars are truly cross-linked autonomous, auto braking and adaptive cruise should be thought of as a second line of defense, not the decision maker when it comes to safe car operation. If somehow you are distracted or suddenly incapacitated (fall asleep is #1), auto systems should save your life and other motorists.

Like airbags, you should have them, but not need them for survival. Very cool technology, but will never be able to do 100% threat assessment, deer strikes come to mind as does wrong way drivers. You should decide your following distance based on current conditions and traffic behavior, something computers cannot do unless cross-linked. Conditions include long range visibility, your "space pillow", and how the driver ahead of is acting (texters need more following distance, since their braking is based on crumple zones during impact, not car performance). You should always be able to easily outbrake the car in front by looking further ahead. Always have a escape plan. ABS allows you to MASH that pedal violently as you firmly steer the car around threats. If you aren't hitting the brake rapidly and with great force, it doesn't do it's job as well, it has to enable ABS before you can steer the car aggressively under max brake effort for the best results. Lanes are 12' wide normally, and you can split lanes like a motorcycle in an emergency to reduce impacts, or keep the tailgater from giving you whiplash.

If you have NOT experienced max ABS braking while rapidly changing directions, it costs between $250 and $2500 to learn this in a safe environment. IMO, should be mandatory, all my family has had it, I have taken many classes, and continue to do so. Classes are fun, and keep you sharp. Most people in classes are surprised how hard any modern car will brake today. Normally the instructor will tell you, "again, faster and harder" during ABS training until you get angry on the brake pedal.

Cliff Notes: Be alert, get training, predict problems.

 

[thegruf]

Here’s the excerpt from the Tesla Manual’s Automatic Emergency Braking section:


“When Automatic Emergency Braking has reduced the driving speed by 40 km/h (25 mph), the brakes are released. For example, if Automatic Emergency Braking applies braking when driving at 90 km/h (56 mph), it releases the brakes when the speed has been reduced to 50 km/h (31 mph).
Automatic Emergency Braking operates only when driving between 5 mph and 85 mph. “


Perhaps the system worked and the emergency breaking kicked in, reduced the speed of the car by 25mph and then disengaged letting the car continue to roll. The driver then applied the breaks hard.

Reading the first post again it seems that both TACC and AEB should have worked (assuming he was travelling >5mph).
This strongly suggest a detection failure.
I am surprised that Tesla have not sent a specialist to test in detail and review the operation of all the sensors and systems involved.
There is a lot of Tesla reputation at stake here.

I have been educated by this thread how AEB works ie reduces by 25mph, or if travellling at <25mph presumably is supposed to stop the car. I can see the thinking here, that at highway speed abruptly braking by 25mph will alert the driver who will instinctively take over, however abruptly braking for say 60mph to a standstill on a highway could be exceptionally dangerous in the event the sensor misdetected a threat (dog running across road perhaps (make that a roo for the Aussies here) ie a brief threat that clears but that sensors could detect as a stationary object).
It is essential that the owner clearly understands the nature of this functionality. I admit I didn't. I doubt I am alone.

However I am confused, consider:

I am travelling at 50mph, the car detects a (eg stationary car) threat in front of me and activates, it reduces speed to 25mph.
I am then doing 25mph, the threat is still there so this is a valid condition for AEB to activate again?

The evidence suggests not, but where is the line in the Tesla text, so specify how the AEB is reset to reactivate?
We can all assume how it works, but for such a safety aid, surely it is critical to explain the operation fully to the user.

 

[Electricfan]

I have not read every post, so if I'm repeating something somebody else said, forgive me.

I think AP may recognize cars faster and better than 18 wheelers. This is based on an unscientific sample size of one - me and my experience. I drive in Houston rush hour traffic 5 days a week on beltway 8, with AP engaged. The car has never come close to rear-ending another car. But today, for the first time since 7.1 came out, I almost hit an 18-wheeler. I would have hit him at about 5 or 10 mph if I had not stomped on the brake at the last second. I let it get extremely close because I wanted to see if the Model S would stop, but it didn't.

What happened was this: I was in the center lane with cruise set to 73 (distance at 7 as always) and the lane was clear in front of me. Then this 18-wheeler decides to pull in front of me from the lane to my right. (I ordered a new dashcam today, will be installed tomorrow, because my dashcam failed me) The Model S started slowing but only on regen. And it didn't start slowing until long after I was aware the truck was pulling in. (because it took it too long to recognize the truck?) I didn't feel the brakes cut in, and that really puzzles me because I know sometimes they do kick on. So, the car slowed but not enough and as I was about to smack the rear of the truck I decided to exercise the better part of valor and step in, braking just in time to keep from hitting it.

I am mystified why Tesla would program the car to let it hit an object it knows is there. Why not brake?? It was slowing quickly on its own. Why on earth did it not use the brakes and slow just a little more to avoid an accident?

The only answer I can come up with is this: I was wrong. It wasn't going to hit the truck. But I've been driving for 40 years, and all my instinct says I would have hit him. Again, I wish I had the dashcam footage, but dashcam is in trashcan now. New one on way.

 

[AWDtsla]

If you have NOT experienced max ABS braking while rapidly changing directions, it costs between $250 and $2500 to learn this in a safe environment.

I don't seem have a problem doing it for free. LOL. How can you trust any car and your ability to drive it you don't push the limits on regularly? In fact when it gets slippery out you should try tapping the brakes or using the throttle often to test surface friction.

 

[Ulmo]

Hi,

I would like to provide an alternative view. It is not necessary to set the TACC distance lower either because your speed changed, because traffic is is heavier (or lighter), or because you are driving in California with more aggressive drivers.

We drive in the San Francisco Bay Area in heavy traffic all the time. Both my wife and I leave the TACC distance set to 7 at all times. While it may be annoying the first few days when a few people cut in front of you, if you are able to take a few deep breaths and relax, you may find that AP allows you to drive with less stress and build a lot less road rage. With the value at 7, there is much more time to react to situations when you need to take over, and once you give up on trying to prevent anyone from 'getting in front of you' your stress level when driving in heavy traffic will go way down. Even at 7, the car will come to a complete stop in heavy traffic, you do not need to lower the value. (The distance decreases dramatically when going at low speeds, I am not sure you can even tell the difference between 4 and 7 when going under 10 MPH, I don't change it, but you are quite close enough even at 7).

I hope this perspective is useful to some,

-Brent

I've always set the Tesla to 7 (max distance) during all my Tesla test drives 100% of the time, and each drive when I had a time where I had to take over, the distance was enough that I easily knew when I had crossed the "threshold" for it being too weird, so it was easy for me to know when to take over. Also, I've almost never had people cut me off for Tesla's "7". I normally have much more following distance than a Tesla 7 when I drive myself in my own car. I was just taught that way. That's when people cut me off left and right. I usually laugh, because I'm very good at lane picking and almost always end up passing them again without trying. I swear by max following distance every time (except when I'm trying to do precise psychological programming of the behaviors of others around me in order to open up a hole or wake someone up, but that's pretty rare after I've educated all the common companion commuters on a particular route and time of day).

I'm much more at risk of becoming bored with driving. I can't wait until "autonomous" is working proficiently enough. I wonder if they realize the gaps in redwood trees above show the next curve angle before you can see it, if they know headlamps reflecting off around curves might be a car, the crest of the road is the middle divider (unless marked), the minimum stopping distance around a turn, looking between the cars to see all the cars ahead for a mile ahead all thousands of them, looking at their weaving back and forth, their inattentiveness, their tail lamps, and can make psychological profiles of each driver from the front view cameras to know what they're all up to and plot routes through them as the car drives ... that's what us experienced human drivers do, so anything less and the autonomous cars aren't going to be that smart. Here's hoping they are.

For now, when it's set to 7, and the car wants to drive you into a concrete center divider, you're already steering it back into the lane, no problem. If you have it set to 2, then all of a sudden you have no idea when to start reacting, and then it's too late already. Who cares if someone cuts you off. That's so irrelevant.

 

[sandstruck]

New Embarrassing (to me) Information from the logs

I received a phone call an hour ago from my Tesla Service manager who told me the following:

My car had been traveling at approximately 40 MPH when it engaged the AEB. He told me that the engineers determined that the car in front of must have slammed on the brakes ("a rapid emergency deceleration"), and the AEB significantly slowed my car, thus avoiding a much worse accident. In fact, the damage to my car is negligible (broken nose cone).

As I repeatedly mentioned in my posts, I remembered something very different transpired--a gradual slowing down, synchronously, with the car ahead of me to about 5 MPH--and a surprising, last-second failure of my car to stop. That's how I remembered it, anyway (I'd have sworn on a stack of bibles). It now seems that my version of events was dead wrong. It makes me wonder how many other memories I have mistakenly fabricated.

The important thing is that I believe Tesla's interpretation of events more than my own. And I want to apologize to everyone who wasted time on this thread and on me, and who believed me at my word. To those posters who accused me of acting irresponsibly by posting before I had the full information from the logs--you were right!

I will slink away now to my basement, inebriate myself perhaps, and marvel at my fallibility, at the frailty of my memory. Mea culpa.

 

[ecarfan]

@sandstruck, again I applaud your openness and thank you for sharing that information from Tesla.
It is well established that human memory can be remarkably inaccurate, especially when a series of events occur very rapidly. And trial lawyers know very well that "eyewitness" accounts where the witness states emphatically that they are accurately describing what they saw may in fact be wildly inaccurate.
I remain convinced that a TACC setting of 6-7 is significantly safer than a lower setting. It not only gives the driver more time to react, it also gives the AEB more time to analyze the situation and respond. It seems likely that a greater following distance might have prevented this accident.

 

[andrewket]

+1 on your transparency. Also +1 on dashcams.

 

[msnow]

No "slinking" necessary @sandstruck. #1 no one got hurt #2 you have proven to be an honest person and #3 it was a stimulating and knowledge provoking thread.

 

[calisnow]

I wonder if they realize the gaps in redwood trees above show the next curve angle before you can see it ... and can make psychological profiles of each driver from the front view cameras to know what they're all up to and plot routes through them as the car drives ... that's what us experienced human drivers do, so anything less and the autonomous cars aren't going to be that smart.

The autonomous cars don't have to be as good as humans at interpreting complex visual pictures - they just have to cause accidents at lower rates than humans do and they will have beaten us at our own game despite being "dumber." As for their ability to interpret complex visual pictures - that will improve continuously of course.

 

[jeffro01]

No "slinking" necessary @sandstruck. #1 no one got hurt #2 you have proven to be an honest person and #3 it was a stimulating and knowledge provoking thread.

Indeed. I want to say "I told you so" but that wouldn't be fair since my original premise was that the OP wasn't being honest. That clearly isn't the case, the OP was being honest based on what they thought happened so I stand corrected in my insinuation that the OP was not being truthful. As always there is a difference between genuinely thinking you're being honest and well, not...

Jeff

 

[calisnow]

And I want to apologize to everyone who wasted time on this thread and on me, and who believed me at my word. To those posters who accused me of acting irresponsibly by posting before I had the full information from the logs--you were right!

You didn't waste anybody's time, nor were you irresponsible in describing your memory of the incident. The only time wasters were the jerks on the thread who attacked you. The discussion itself has been very helpful.

 

[Ivo-G]

Sandstruck, thanks for sharing it all with us. When so many can post about nags or delivery times or what they bought for X-Mas and who knows whatever other topics, you chose to share with us one of the most horrifying moments a (new) car owner could experience, and I for one definitely learned a lot from it. These lessons will stick with me for a long time I hope and may one day save me from being in such a situation myself.

 

[msnow]

Indeed. I want to say "I told you so" but that wouldn't be fair since my original premise was that the OP wasn't being honest. That clearly isn't the case, the OP was being honest based on what they thought happened so I stand corrected in my insinuation that the OP was not being truthful. As always there is a difference between genuinely thinking you're being honest and well, not...

Jeff

True but you did call it right when you said to wait...that we didn't have all the information. I'm glad that Tesla was more forthcoming with what the logs showed rather than the "sir we are not responsible" comments.

 

[bhzmark]

My car had been traveling at approximately 40 MPH when it engaged the AEB. He told me that the engineers determined that the car in front of must have slammed on the brakes ("a rapid emergency deceleration"), and the AEB significantly slowed my car, thus avoiding a much worse accident. In fact, the damage to my car is negligible (broken nose cone).

That's exactly how AEB is supposed to work.

But was TACC on? And if so, why didn't it stop the car?

 

[McRat]

I received a phone call an hour ago from my Tesla Service manager who told me the following:

My car had been traveling at approximately 40 MPH when it engaged the AEB. He told me that the engineers determined that the car in front of must have slammed on the brakes ("a rapid emergency deceleration"), and the AEB significantly slowed my car, thus avoiding a much worse accident. In fact, the damage to my car is negligible (broken nose cone).

As I repeatedly mentioned in my posts, I remembered something very different transpired--a gradual slowing down, synchronously, with the car ahead of me to about 5 MPH--and a surprising, last-second failure of my car to stop. That's how I remembered it, anyway (I'd have sworn on a stack of bibles). It now seems that my version of events was dead wrong. It makes me wonder how many other memories I have mistakenly fabricated.

The important thing is that I believe Tesla's interpretation of events more than my own. And I want to apologize to everyone who wasted time on this thread and on me, and who believed me at my word. To those posters who accused me of acting irresponsibly by posting before I had the full information from the logs--you were right!

I will slink away now to my basement, inebriate myself perhaps, and marvel at my fallibility, at the frailty of my memory. Mea culpa.

Probably not news, but when "exciting" things happen that cause adrenaline to kick in, your perception of time and speed changes. Everything slows down. It's normal, and nothing to be embarrassed about.

 

[ModelX]

Thanks for sharing, both your original perceptions and your new knowledge!:smile:

 

[Andyw2100]

My car had been traveling at approximately 40 MPH when it engaged the AEB. He told me that the engineers determined that the car in front of must have slammed on the brakes ("a rapid emergency deceleration"), and the AEB significantly slowed my car, thus avoiding a much worse accident. In fact, the damage to my car is negligible (broken nose cone).

Thanks for the follow-up, sandstruck. No need to apologize!

For those who are not interested in a dashcam as an option to be able to go back and at least partially recreate for yourself something like this, should it happen, the logging sites / software now available might be good alternative solutions. If sandstruck had been using one of them, he could have checked the log of his speed himself almost immediately after the accident.

Visible Tesla is free software that would allow you to log your car's activity. Two newer services are EVMote and TeslaLog. There are threads here on TMC on all three.

That's exactly how AEB is supposed to work.

But was TACC on? And if so, why didn't it stop the car?

TACC was on. The OP has said this many times, and it was confirmed by Tesla. The reason it didn't stop the car was that the target car did "a rapid emergency deceleration." TACC is not designed to slow the car in that situation. AEB kicked in, and did reduce the impact of an unavoidable frontal collision, which is what it is supposed to do.

 

[gothmog2]

He was following at 2 car length difference. If it had been four lengths AEB might have had enough time to stop. If the car in front does an emergency stop, AEB can only do so much at close range (and did what it could)

Thanks for sharing, Sandstruck.