Automatic Emergency Braking in AutoPilot with v8.0 Avoids Serious Accidents Such As This


Recently one my closest friends in the world had brush with disaster while driving his Tesla Model S on the freeway.

I often see anecdotal stories and dash cam videos posted about Tesla AutoPilot and Emergency Braking from time to time.  I always intriguingly read with my engineering eyes how the system functions. However, my reaction was much different this time.  Jeff and I grew up on the same block, played shortstop and second base together, spent holidays together, etc.  This time it hit close to home.

Jeff with his Model S

Jeff with his Model S

Jeff received his Model S 85 in the winter of 2015.  As a physician covering numerous offices in the Tampa/St. Pete area, he drives 18,000 miles per year on average, mostly highway.  For those not familiar with Florida, the highways are flat, straight and boring; the ideal setting for AutoPilot.  It has provided him the opportunity to travel roughly 12,000 miles with AutoPilot engaged.

To give you a idea of the kind of view Jeff was working with. (It wasn't a FedEx truck, best example I could find)

Here is an idea of the kind of view Jeff was working with. (It wasn’t a FedEx truck, but similar size and lack of windows.)

His incident occurred during rush hour on the highway approaching a construction zone.  Jeff was in the right hand lane traveling 60 mph behind a small box truck (think little moving van) with the follow distance set to 2.  To avoid a debate of following distance, this speed and spacing is very normal during city rush hour.  If you add any extra space, an impatient car will fill it.

He noted on the User Interface, AutoPilot was tracking not only the truck in front of him, but the vehicle in front of the truck he was unable to see since the truck had no windows.  New since the recent software update to v8.0.

Suddenly full emergency braking was activated…

Jeff was completely unaware of the situation unfolding out of his view.  The vehicle in front of the truck had abruptly stopped for road debris.  The truck either choose not to or was not able to stop, instead veering off the highway – leaving Jeff facing a stopped vehicle.  Since Automatic Emergency Braking (AEB) activated before the truck veered off the highway, the Model S stopped with room to spare.  The full incident measured just a few seconds, covering not much more than 100 feet.

Thankfully not the outcome of this incident.

Thankfully not the outcome of this incident.

Living in Houston, I see results of these situations too often, except drivers don’t have AutoPilot or Automatic Emergency Braking, and they don’t have the same fortunate outcome.  If Jeff had been driving manually, he said there is a chance he would have been following closer, and no chance he could have stopped in time without AEB.

This technology needs to become standard on all vehicles, not just Teslas or luxury cars, all vehicles. Trucks (light duty and heavy) and SUVs need AEB the most.  0.5 x Mass x Velocity ^2 is the governing equation to the energy involved in a collision.

Most of all, I am thankful that Jeff’s Model S didn’t just allow him to walk away from a bad accident, but prevented it.  He went home to his wife and child spooked, but not injured.


You can find his words on this TMC post here.  I spoke with him on the phone after the incident to fill in the extra details here in this story.

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55 Comments on "Automatic Emergency Braking in AutoPilot with v8.0 Avoids Serious Accidents Such As This"

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It’s one thing to follow too close to a normal car, where at least you still have some visual around and in front of them. It’s another thing to tailgate a truck where you can’t see anything. This is poor driving plain and simple. Yes, technology saved his a$$, but proper driving would have eliminated that need.

What happened to the car BEHIND your friend? How did they stop in time without a Tesla to save them?

Valid point however an accident was avoided which is the intent. If everybody would drive responsibly it wouldn’t be a need for accident avoidance systems.

Yes, and if everybody would just get along there wouldn’t be a need for an Army.

I absolutely agree. Under normal driving conditions a minimum 2 second gap is recommended which equates to about setting 5 or 6 at speed (on my MS, at least). So what if ‘somebody fills the gap’? At least you are driving responsibly and to put a more altruistic spin on it, it gives *your fellow travellers* a safe opportunity to overtake/change lanes.

Of course, eventually, we will all be driving along with 6 feet or less between vehicles – or rather, ‘we’ wont, but our cars will!

AEB should of course be standard. Just like Volvo has been doing since 2014.

And you can’t get 5 stars on the Euro NCAP without AEB since 2014 thankfully. People easily understand that “less than 5 stars” generally means that it’s not something that they should buy.

I’m generally not impressed by the attention that Tesla has gotten for simple things like the standard AEB that most manufacturers have been doing long before Tesla. But in this case I’m impressed.

AEB with a restricted view in between gets chalked up on the better than ordinary board. Kudos to Tesla on this one.

You are missing the main point of the Tesla advantage even tho it has received a lot of press and was repeated in this story.

Tesla tracks TWO cars ahead with radar underneath the 1st car so it can react to that 2nd car even is the 1st car does not.

“AutoPilot was tracking not only the truck in front of him, but the vehicle in front of the truck he was unable to see since the truck had no windows”

Good to hear everyone is alright. Scary stuff.

Why are they showing a Crashed Tesla on the Curb.??

“If you add any extra space, an impatient car will fill it.”

Very annoying behavior that people display in dense traffic. I’ve run into it many times. It forces you to follow more closely than you otherwise would.

Good story Josh. I didn’t know you were an engineer. I’ll listen to your posts more closely from now on:)

It’s better to add extra space and have an impatient car that you can see beyond fill it, than be too close to a truck IMO.

The problem isn’t the one car filling in but autopilot slowing you down to gain that distance back from the new car in front of you leaving another big gap that the next car will then fill in. Rinse repeat.

This keeps pushing you back further and further slowing your speed down more and more to where you become and obstacle as more people pour around you because you are driving too slow.

I’ve experimented with this under manual driving and you just become like a rock planted in the middle of a stream with traffic pouring around you.

There is a magic distance that you can drive where you are a safe distance but can accelerate just a little to deny any antsy drivers that you see beginning to attempt to squeeze in front of you.

Unfortunately autopilot can’t mimic this behavior so it has to be set closer to the car in front of you which isn’t as safe but autopilot has better reaction time, the ability to see what the car 2 ahead is doing and has superior precise braking to compensate.

Yup, drivers like that make congested driving way worse and contribute to more congestion.

Leaving big gaps, letting people cut in, constantly braking are annoying. Just drive slow and steady. Even then, some forget to speed up when traffic frees up.

Having extra space in front of you doesn’t force you to follow more closely, you choose to do so.

I can tell you from experience that you will still get to the same place you were going, and almost always will add less than ten percent to your travel time if you leave the extra space. Even in heavy traffic.

And you’ll arrive far more relaxed and calm when you do because you didn’t spend your whole commute activating your “fight or flight” instincts during your trip.

From my experience, driving a Model S at 60mph with Autopilot on using a spacing setting of 2 does not equate to tailgating. It is a comfortable and safe following distance.

Obviously not! This incident is case-in-point that it is not safe if you can’t see past the car/truck in front of you.

No need to berate the driver, because we’ve all been there with more or less luck, but let’s also be honest. When your skin is saved by AEB, you (the driver) have made a mistake. All accidents are preventable.

All accidents are not preventable by you. The risk of error by other drivers can be mitigated to a degree, but just for one extreme, demonstrative example: if you’re driving and someone decides to turn into you quickly as hard as they can from the lane next to you (e.g. because they’re drunk), there’s nothing you’ll be able to do to prevent that. Your reaction time is somewhere very close to .25 seconds, and traveling at 70 mph means that a 45 degree turn will have the other car traveling at 50 mph (which is equal to 73.333 feet per second) toward you. Given that there is about 6 feet of space between you, that means you have 6/73.333 or .08 seconds to react. No human’s reaction time is that fast, but a self driving car could potentially react that quickly.

All accidents are preventable in the sense that they start by someone making a mistake. This does not mean we can reasonably hope to eliminate all accidents, but driving too close of a truck with no view past it is asking for trouble. I hope we can all agree on that.

With that said, I also concede that AEB could save someone who is not at fault (see Pushmi’s example), but even then, there are ways to drive defensively that reduce the risk to everyone involved. I’m currently teaching my daughter to drive, and I am amazed at the number of potential dangers I can point out to her at any time, things that good experienced drivers internalize, and tell her to slow down, or do this or that to mitigate the risk, whether or not she is in her right.

Dan Hue said:

“All accidents are preventable.”

But only if you never get out of bed, or if you have a perfect ability to predict the future. Not so much for real-world living.

What does a “setting of 2” mean? Two seconds (what I was taught in driver’s ed)?

I also wonder what the car behind the Tesla would have had to do. Despite that, I do think such technology is good. Really good.

2 car lengths perhaps? In any case, the setting of 2 is FAR from ‘safe’. The correct minimum separation distance (at least by European standards) is at least 2 seconds gap.

The numbers have no distance value. The distance varies with the speed of the car so the setting is just a number.

I am under the impression that off the Race track and On “PUBLIC ROADS” you should leave 1 car length for every 10 mph travel speed, so 60 mph you should be (6)SIX car lengths away from the guy in front of you Mr Andretti.

A 2 setting in Tesla TACC (aka adaptive cruise control) is not car lengths. It is just a relative number from 1 to 7 and the distance depends on how fast you are traveling. 2 at 40 MPH is a different distance than 2 at 70 MPH.

The problem in rush hour or heavy highway traffic is that if you leave 6 car lengths ahead another car will fill in immediately leaving you 8 car lengths back from the original car. Then another will fill in 2 seconds later leaving you 10 car lengths back, etc.

After a few minutes you’re in the right lane being pushed back further and further, slowing down more and more to where you are doing 45 mph.

Heck, in a lot of cities, they’ll squeeze in if you leave two car lengths.

Sounds like you’re A Road Hog…Share the Road it’s The Law!

Personally, if I get stuck behind a truck, I make it my priority to change lanes, if possible…..

This could have been avoided by not tailgating a truck. So what if someone gets in front of you? Then back off them. Poor driving.

Everyone seems to have missed the fact that the box truck driver was most likely tailgating even closer and that’s why he/she had to swerve out of the way. Because there was no room the brake.

His/her vision most likely was better in a higher profile vehicle where he/she should’ve been able to see over the car in front.

This is an interesting story.

As a defensive driver, I would never follow closely if I can’t see the car two in front of me.

Assuming that Jeff is a defensive driver left to his own devices (I know that’s a big assumption), it makes me think that the autopilot system created the situation by using a global following distance setting of 2, when a human would have adjusted for the situation.

So, the autopilot saved Jeff from real harm, but also helped cause the situation in the first place.

On the other hand, people w/o autopilot get into situations just like this all the time, so it must be common.

This seems like a chance to add sophistication to the autopilot system to drive using the conditions farther ahead than the car in front of us. although there is a reference to it in the article.

My user interface does not look like that.

Yes. I am surprised there are no other comments about this. Is this a new interface from a beta tester’s car?


WOW! Okay, pass the salt… I am gonna have to eat some crow here. I said that there was no way that a Tesla car could “see” another car through an intervening car, unless the Tesla had an unobstructed “view” through the windows of the car immediately in front. Clearly I was wrong. I admit to being baffled here. How can radar, or any other sensor, “see” through the solid walls of a truck? I know that Tesla, or a Tesla spokesman, claimed that the Tesla sensors could “see” underneath the car in front, to the 2nd car in front of that, by bouncing radar off the road. But this would require not just a single bounce off a rough surface, but two; one bounce outgoing, on bounce incoming. I really don’t see how such a scattered return could possibly be used to construct a useful image. It’s not like the asphalt or the concrete of a road has a mirror-like surface, which would give a good reflection. Such a rough surface should scatter the radar waves, not once but twice, unless my understanding of basic physics is fundamentally flawed. But at any rate, congratulations to Tesla on its awesome… Read more »
Will Davis said: “It’s better to add extra space and have an impatient car that you can see beyond fill it, than be too close to a truck IMO.” It’s not clear exactly what the traffic situation was; the article only says that it happened on the highway, and not whether it was a multi-lane highway or a two-lane highway with two-way traffic. But I can tell you from personal experience that if you try to maintain a 2 second following distance in moderate or heavy traffic on a multi-lane highway, what will happen is that there will be a continuous stream of cars cutting in front of you, one after the other. So there really is no point to trying to maintain that distance, because you simply can’t. About 1.5 seconds is the best you can hope for, and even that sometimes isn’t possible. In really heavy traffic, you may have to reduce it to 1.25 seconds. Don’t believe me? Then try it sometime. Look at the dotted line in between the lanes, note when the back of the car you’re following passes one of those gaps. Count seconds until the front of your own car reaches that same… Read more »

I think it depends on the local driving customs. Some places you can do it, others not so much. For example, when I drive in Toronto, people cut me off by changing lanes too close in front of my car if I try to keep a sufficient distance. The only way to do it there is to drive faster than the flow of traffic. I don’t remember having this problem in Florida but driving there is difficult because many people drive too slow, while many others drive too aggressively.

“…many people drive too slow, while many others drive too aggressively.”

Yes, that’s one problem with computer traffic simulations, and it will be something that I suppose those writing software for self-driving cars (or more specifically, for how self-driving cars should interact with human-driven cars) will eventually have to consider: That there are different styles of human driving; some aggressive, some timid, some in between. That’s why traffic simulation programs work better when they assign distinctly different levels of aggression to different vehicles; that allows a better model, closer to real-world traffic conditions.

Well Done Tesla!

I wonder if this emergency braking technology also restricts the driver from running into a building or anything when pressing the accelerator instead of the break.

Simply just refusing to impact any object without a manual override of some sort.

“I wonder if this emergency braking technology also restricts the driver from running into a building or anything when pressing the accelerator instead of the break.”

We can hope that Tesla will introduce that upgrade soon, but at last report Autopilot didn’t function at low speeds… as I recall, about 15 MPH or less. Not that all collisions with buildings happen at low speed, but I think most of them do.

Personally, I think that if you don’t have enough room between your car and the car in front to avoid hitting it due to something unforeseen happening, then you are DRIVING BADLY.

How difficult is it to leave enough distance between your car and other moving or stationary objects? You can ALWAYS leave more distance. Most people don’t because they become complacent (because, usually, nothing bad happens even if they’re driving too closely). But, being complacent is just one aspect of BAD DRIVING.

In California, the law reflects this. If you hit a car in front of your car, it is automatically your fault. You either, a) you were simply “driving into things” because you’re not paying attention or, b) you didn’t leave enough enough room to avoid hitting the car in front in case something bad happened.


Easily avoidable if you are PAYING ATTENTION

All these moron proof safety features are useless for people that know how to drive.

No safety features on my Volt. No need for them. I am the safety feature in any vehicle I am operating.

I agree with that. For one I would never be in such a situation. If a panel truck is in front of me I just back off, so what if someone cuts in, unless they are another panel truck.
Usually with semis you can give them a lot of room since few want to jump behind a semi.

I could tell some stories after 20 years OTR.

That’s nice in theory, but in reality somebody is gonna be the one driving behind the big truck that blocks the view of anything in front of it.

You can, of course, ensure by your own personal driving behavior that you never will be. And I understand the feeling; when I was still driving, I made a point of never driving closely behind any dump truck or any flatbed trailer with a load chained or strapped onto it.

But self-driving cars won’t have any such luxury. They’re going to have to be programmed to exhibit the same or very similar driving behavior regardless of what vehicle happens to be in front of them on the highway. It’s all very well to say “well, the self-driving car could just leave a much longer gap if the vehicle in front is large”, but in reality I don’t see car buyers putting up with that behavior from self-driving cars. They just won’t buy vehicles programmed that way.

I don’t buy the agreement of following too close because others will fill the gap. I always keep sufficient distance and ignore the cars that fill the gap. Drive defensively and these kinds of situations can and will be avoided. Nothing against autopilot but the driver is at fault. He got lucky he was not rear ended.

Argument, not agreement.

Also, great news that autopilot worked well and protected the doctor and everyone else. I am thankful nobody got hurt.