# Will Autopilot 2.5 slow down for merging traffic?



## RIP_OPEC (Jul 15, 2018)

I have my following distance set to the highest value, 7, and I am wondering if Autopilot will eventually slow down to avoid a collision when a vehicle on the ramp suddenly merges over in front of you.

Several times I had to disengage autopilot and manually slow down when a vehicle merged in front of me, as the tailgating made me feel uneasy and I was worried it would cause an accident.

The screen displayed the car in the adjacent lane, so it knew it was there.


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## SoFlaModel3 (Apr 15, 2017)

Autopilot does not handle merging yet, but I’m sure it will eventually. 

As an aside, 7 seems like an overly cautious setting in my experience. At speed, I use 3 and in traffic in lower speed I use 1 and then 2 at slightly higher speed. Have you tinkered with that yet?


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## Ed Woodrick (May 26, 2018)

Cars merging on are responsible to merge, not the cars on the main road. It is actually a little frustrating and dangerous if the car on the mail road adjusts speed for merging vehicles.
But, if a car moves in front of you, the adaptive cruise control will adapt.

And yes, 7 is a long gap, which makes it a higher probability that cars are going to jump in front of you. 4 is a much safer standard number and 1 or 2 is better in slower stop and go traffic.


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## RIP_OPEC (Jul 15, 2018)

SoFlaModel3 said:


> Autopilot does not handle merging yet, but I'm sure it will eventually.
> 
> As an aside, 7 seems like an overly cautious setting in my experience. At speed, I use 3 and in traffic in lower speed I use 1 and then 2 at slightly higher speed. Have you tinkered with that yet?





Ed Woodrick said:


> Cars merging on are responsible to merge, not the cars on the main road. It is actually a little frustrating and dangerous if the car on the mail road adjusts speed for merging vehicles.
> But, if a car moves in front of you, the adaptive cruise control will adapt.
> 
> And yes, 7 is a long gap, which makes it a higher probability that cars are going to jump in front of you. 4 is a much safer standard number and 1 or 2 is better in slower stop and go traffic.


Thanks for the advice, I have lowered the following distance. I had it set to 7 because I thought it would reduce the swerving right then back left when an exit lane approaches and the right line is temporarily gone. Didn't seem to have much effect.


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## Enginerd (Aug 28, 2017)

Ed Woodrick said:


> Cars merging on are responsible to merge, not the cars on the main road.


Currently driving a Prius, and I must humbly say that sometimes I need a little bit of help from the "main road" cars to integrate myself on the interstate. But, I'm up to the speed limit by 30 seconds, easy.


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## timtesla (May 9, 2018)

I use 1 at all times. Otherwise, people will just merge in front of you at all times, and autopilot requires me to slow down manually too often. Right now it doesnt seem to look for merging traffic, i hope that comes soon, as it would make autopilot much more usable. I live in a big crowded city, so we are used to driving super close anyways.


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## MelindaV (Apr 2, 2016)

timtesla said:


> I use 1 at all times. Otherwise, people will just merge in front of you at all times


This really will vary depending on the type of traffic (type of drivers) you have.

At speed, most drivers here do not drive right on the bumper of the car ahead of them, and people are allowed to merge when they need to. In stop and go traffic, most are feet from the car they are following and lane changes are more of an eye contact sort of agreement with who is moving over and who is letting them over (something difficult for a personless FSD car to do). You can't always just not let others merge...


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## John (Apr 16, 2016)

I had several merging situations yesterday, which I was paying close attention to because I was helping a friend on their Model 3 delivery day, and he and his son were driving my car beforehand while I taught them the various systems. So we were noticing and commenting on merging a few times.

Autopilot is "safe" if someone cuts you off right in front of you, like even just three feet ahead (which makes you think you're about to touch, though there's actually clearance). In past versions it didn't always work this well, but it has gotten very solid.The car doesn't freak out, it just backs off smoothly.

That having been said, it won't cooperate with a person beside you. My guess—and it's just a guess—is that only forward cameras are fully incorporated in the control loop right now. Perhaps the side cams are observing in shadow mode, but the car does not alter speed for a car that obviously needs to merge and is just pacing you. To echo what Melinda was saying, I know that at least in California there is a good deal of cooperation that occurs to ease merging, and it helps to be aware that some people really do defer part or all of the responsibility to people already on the highway. I suppose personality-wise, it's no different that people that walk down the sidewalk and expect other people to get out of their way. Some people are kind of oblivious that way, and I'm sure at times when I am distracted I am as well. Depends on what's going on. But right now Autopilot drives just like someone who refuses to budge to let someone in. Once or twice I was tempted to tell the driver of my car to drop out of Autopilot to help, but in each case the merging driver finally sorted it out (speeding up or slowing down to merge with us).

For this and other reasons, I always encourage people to think of the center lanes—not the far right or far left—as the best Autopilot lanes. Almost nothing interesting happens in the middle lanes, at least until you come to forks in the highway, which need to be anticipated so that you can put the car in an "unambiguous" lane for Autopilot to follow.


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## tivoboy (Mar 24, 2017)

I find that the car lengths distance setting is really off by nearly a factor of 2. If I really want to be 4 lengths from the car in front, I have to set it to 2 or 3 at the most. If I want 6, it should be about 3. Now, it might not MEAN car lengths, it could be some other value. It's a 1, 2 or 3, etc.


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## Phillyasian (Sep 19, 2017)

tivoboy said:


> I find that the car lengths distance setting is really off by nearly a factor of 2. If I really want to be 4 lengths from the car in front, I have to set it to 2 or 3 at the most. If I want 6, it should be about 3. Now, it might not MEAN car lengths, it could be some other value. It's a 1, 2 or 3, etc.


The scale is DEFINITELY NOT Car lengths.


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## timtesla (May 9, 2018)

MelindaV said:


> You can't always just not let others merge...


Its not that i'm trying to be a jerk and stop people from merging, but autopilot cant detect cars trying to merge and brakes quite hard and uncomfortably when they finally enter your lane. By driving on 1 and leaving little space, its a much smoother ride


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## Tophoos (Jul 10, 2018)

Before I got the car and hear propel talk about this distance being "car length", I always wondered why the heck engineers would have chosen such a dumb metric.

After my limited use with AP so far, I think it is generally using number of seconds. That is, if the car in front of me hits an immovable wall, how long it will take for me to crash right behind that car. This measurement gives you more distance at high speeds and less distance at lower speeds.


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## Sparky4life (Jul 27, 2018)

Tophoos said:


> Before I got the car and hear propel talk about this distance being "car length", I always wondered why the heck engineers would have chosen such a dumb metric.
> 
> After my limited use with AP so far, I think it is generally using number of seconds. That is, if the car in front of me hits an immovable wall, how long it will take for me to crash right behind that car. This measurement gives you more distance at high speeds and less distance at lower speeds.


That is correct. It's time-based, not distance based. Each increment corresponds to half a second, so as value of 4 means you are 2 seconds behind the car ahead of you. As your speed goes down, the distance decreases for the same setting.


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## John (Apr 16, 2016)

timtesla said:


> Its not that i'm trying to be a jerk and stop people from merging, but autopilot cant detect cars trying to merge and brakes quite hard and uncomfortably when they finally enter your lane. By driving on 1 and leaving little space, its a much smoother ride


Mine's gotten very smooth on cut in merges. Helps if they are moving faster than you (which is the polite thing for them to do, not jump in front and slow down).

Here's a video of how well it works in stop and go. The silver-blue car to the right just totally nosed me out without "asking."

P.S. Follow distancewas set to 1.


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## Falkirk (Mar 5, 2018)

This isn't a merging scenario but I'm waiting for Autopilot to handle cross traffic better. I now know what to expect but it's amazing how much the Model 3 slows down for a car way way ahead on the road crossing through the lane, even with the following distance of 1. It's like the car can't process fast enough and becomes jerky with its motions of slowing down then speeding up when the car is pretty much already gone through the lane. No human driver would ever react to this situation I'm describing other than maybe ease off the accelerator a touch but here's hoping v9 improves this again!


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## John (Apr 16, 2016)

Falkirk said:


> This isn't a merging scenario but I'm waiting for Autopilot to handle cross traffic better. I now know what to expect but it's amazing how much the Model 3 slows down for a car way way ahead on the road crossing through the lane, even with the following distance of 1. It's like the car can't process fast enough and becomes jerky with its motions of slowing down then speeding up when the car is pretty much already gone through the lane. No human driver would ever react to this situation I'm describing other than maybe ease off the accelerator a touch but here's hoping v9 improves this again!


Yeah it does wait an awkward amount of time until the car is COMPLETELY out of the lane before it resumes speed and takes the space the other car left.

But remember, you can just press the accelerator to make up for that, with no foul.


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## Falkirk (Mar 5, 2018)

Funny the IIHS just came out with a report and this sounded familiar!

_"Unnecessary or overly cautious braking is an issue IIHS noted in the Model 3. In 180 miles, the car unexpectedly slowed down 12 times, seven of which coincided with tree shadows on the road. The others were for oncoming vehicles in another lane or vehicles crossing the road far ahead."
_
_https://electrek.co/2018/08/07/tesl...keeping-iihs-fails-auto-braking-test-model-s/_

_It'll get tweaked soon enough for the better._


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## ateslik (Apr 13, 2018)

follow distance 1, 24/7. But I always turn on chill mode when using AP, which helps the hard braking a lot.


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## NR4P (Jul 14, 2018)

I have distance set to 2. Love Autopilot.
And it does detect merges and slows down. If a car starts to cut in front of me, it does slow down, but admittedly it does this better when its lane to lane vs entrance ramp. Entrances and exit ramps are not handled great.

Example, a week ago in the dark, raining, I was using AP at about 60 mph on Interstate. I signaled to move to lane on right. AP started moving to right and then cut back hard to my center lane. A car had entered where we were headed and AP avoided it. It was dark and raining and not sure I would have seen the car if 100% on me.


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## SoFlaModel3 (Apr 15, 2017)

Falkirk said:


> Funny the IIHS just came out with a report and this sounded familiar!
> 
> _"Unnecessary or overly cautious braking is an issue IIHS noted in the Model 3. In 180 miles, the car unexpectedly slowed down 12 times, seven of which coincided with tree shadows on the road. The others were for oncoming vehicles in another lane or vehicles crossing the road far ahead."
> _
> ...


This has happened to me less than 5 times in 10,000 miles so it strikes me as odd that they had it happen 7 times in 180 miles. Speaking specifically to the shadow effect.


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## evannole (Jun 18, 2018)

SoFlaModel3 said:


> This has happened to me less than 5 times in 10,000 miles so it strikes me as odd that they had it happen 7 times in 180 miles. Speaking specifically to the shadow effect.


Interesting. It has happened more frequently for me in my 1000 miles of ownership, though I have noticed a pattern: it happens just before entering very deep shadows. A relatively narrow underpass doesn't do it, but the very wide underpass under I-20 while traveling on I-75/85 in downtown Atlanta does. That's a good 100+ yards of shadow. Perhaps it sees the small shadows but can also see well beyond them, thereby realizing that there's not all problem, but maybe when it encounters such a deep shadow that it's difficult to see what's beyond the shadow that it thinks that the shadow is actually a solid object.

This behavior also happened yesterday on the highway when approaching not an underpass, but a relatively large patch of standing water on the road during a heavy rainstorm. It was not a significant slowdown, but enough of one to get my attention. I will say, however, that if the car deliberately slowed because of a large amount of standing water, that might actually be a good thing.


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## SoFlaModel3 (Apr 15, 2017)

evannole said:


> Interesting. It has happened more frequently for me in my 1000 miles of ownership, though I have noticed a pattern: it happens just before entering very deep shadows. A relatively narrow underpass doesn't do it, but the very wide underpass under I-20 while traveling on I-75/85 in downtown Atlanta does. That's a good 100+ yards of shadow. Perhaps it sees the small shadows but can also see well beyond them, thereby realizing that there's not all problem, but maybe when it encounters such a deep shadow that it's difficult to see what's beyond the shadow that it thinks that the shadow is actually a solid object.
> 
> This behavior also happened yesterday on the highway when approaching not an underpass, but a relatively large patch of standing water on the road during a heavy rainstorm. It was not a significant slowdown, but enough of one to get my attention. I will say, however, that if the car deliberately slowed because of a large amount of standing water, that might actually be a good thing.


To be fair I should walk back my statement. I do not drive under many overpasses which is where this issue happens 99% of the time.


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## Sparky4life (Jul 27, 2018)

It feels like merging has gotten a little better in the 28.x updates. Prior to 28.x, the merging vehicle needed to be at least halfway into your lane before Autopilot would back off, now it does that a little earlier. It also does a better job of auto-lane changing when there is a slower vehicle ahead in the target lane. It will now slow down before making the lane change in order to slot in behind the other vehicle. Seems like prior to 28.x it would just refuse to make the lane change.


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## iChris93 (Feb 3, 2017)

Sparky4life said:


> It feels like merging has gotten a little better in the 28.x updates. Prior to 28.x, the merging vehicle needed to be at least halfway into your lane before Autopilot would back off, now it does that a little earlier. It also does a better job of auto-lane changing when there is a slower vehicle ahead in the target lane. It will now slow down before making the lane change in order to slot in behind the other vehicle. Seems like prior to 28.x it would just refuse to make the lane change.


I'm on 26.3 and the car will slow down before changing lanes.


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