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Reading Speed Limit Signs – Autopilot Crippled

tonybelding

Active Member
Aug 17, 2006
1,478
797
Hamilton, Texas
I’ve been waiting for someone to post about this, but I guess it’s up to me.

Since the last update, my Model S has begun reading speed limit signs using its cameras rather than relying only on Google map data. Google’s speed limit data is usually but not always correct, so I’ve been wanting for a while for the car to read the signs itself.

Now I got what I wanted, and it’s a bit of disaster. The car does a pretty good job of reading signs up to 60 MPH but is blind to anything faster. After days of testing, I have never yet seen it correctly read a sign faster than 60. (In a construction zone it did mis-read one 65 sign as 45 and a couple as 55!) It is completely blind to 70 and 75 MPH speed limit signs.

This leaves Autopilot effectively crippled. It means that every time I leave town — any town — and the speed limit goes from 60 to 70 or 75, Autopilot remains restricted to 65 MPH max. Cruising down the highway on autopilot at 65 MPH while most other drivers are zipping along at 75 or 80 is not really acceptable. We’ve heard a lot about crippled Autopilot in Europe, but now it seems we get crippled Autopilot in the USA.

Workarounds… One trick I’ve found is to pull over and turn off on the first side road (typically a county road) that I encounter, then immediately turn around and get back on the highway. This causes the car to reset its speed limit and revert to Google’s data. This is the only way I’ve found to get Autopilot back up to speed on the highway — until I reach the next town and the next speed zone. I found that this only works if I pull onto a numbered road that the car (or Google, I guess) interprets as having its own speed limit. Just pulling off the side of the road, private drive, roadside park, etc., is not enough to trigger the reset.
 

Daniel in SD

Well-Known Member
Jan 25, 2018
6,561
9,316
San Diego
It is completely blind to 70 and 75 MPH speed limit signs.
As far as I know we don't have any speed limits above 65mph on undivided highways in California. It would be funny, in a sad way, if that is the reason.
On divided highways you can set Autopilot speed up to 90mph so I don't think it uses speed limits at all.
 
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thewishmaster

Member
Jun 4, 2018
546
429
California
Generally I’ve seen it only react to signs on +5mph limit roads (although some residential streets in my area have neither AP speed restrictions nor speed limit signs to test with). I believe this is all part of the “local roads” disclaimer in the release notes.
 

TresLA

Member
Jul 15, 2018
71
64
L.A.
I have not experienced this problem since the sign reading update nor have I heard of others experiencing it. Granted I’m only driving divided highways with 65 MPH speed limits, but I’m always set to 9 above speed limit in settings so it defaults to 74 MPH speed limit. I still sometimes spin the dial to raise it up to 79 but have never seen AP reduce the limit due to reading any signs incorrectly. I know it’s reading speed limit signs correctly though, since in construction zones it’s reducing the speed limit accordingly, then raising back up automatically when a normal speed limit sign flies by. In any case, on divided highways it shouldn’t prevent you from raising the limit all the way up to 90.

Perhaps try submitting a service request in the Tesla app or call service to look into your vehicle?
 
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tonybelding

Active Member
Aug 17, 2006
1,478
797
Hamilton, Texas
I have not experienced this problem since the sign reading update nor have I heard of others experiencing it. Granted I’m only driving divided highways with 65 MPH speed limits,

I haven’t tried testing on any divided highways since the update. The nearest one is about 60 miles away from my home, and I haven’t had occasion to travel in that direction.

but I’m always set to 9 above speed limit in settings so it defaults to 74 MPH speed limit.

uhh… As far as I know, it’s not possible for Autopilot to work higher than +5 over whatever the car thinks the speed limit is. (Cruise control is happy to go higher, but not Autopilot/Autosteer.) I haven’t found any way to change that.

I know it’s reading speed limit signs correctly though, since in construction zones it’s reducing the speed limit accordingly, then raising back up automatically when a normal speed limit sign flies by.

uhh… As far as I know, Autopilot never automatically increases speed after reducing it for a speed zone. It used to do that way back in the Mobileye days, but my 2020 Model S never has, which is annoying.

Perhaps try submitting a service request in the Tesla app or call service to look into your vehicle?

I’m thinking about it. My intuition is that this is a limitation of the current firmware that they can’t just “fix” until it’s updated, but it might be interesting to see what the response is anyhow.
 

Daniel in SD

Well-Known Member
Jan 25, 2018
6,561
9,316
San Diego
uhh… As far as I know, it’s not possible for Autopilot to work higher than +5 over whatever the car thinks the speed limit is. (Cruise control is happy to go higher, but not Autopilot/Autosteer.) I haven’t found any way to change that.
You can set it up to 90mph on divided highways even if the speed limit is 65mph (maybe 55mph too, dunno).
 
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animorph

Active Member
Apr 1, 2016
2,143
1,538
Scottsdale, AZ
We just finished a long trip, using 2020.36.3.1 for the return. Starting out, it read and displayed all (and only) standard white rectangular speed limit signs. Any additional signage above or below the standard sign would cause that sign to be ignored. By "ignored" I mean not displayed on the visualization and no change in displayed speed limit, right or wrong.

It definitely read the speed limit signs for limited-access divided roads, including 75 MPH signs.

We went through one entire state (Oklahoma?) I think where no speed limit signs were recognized. They looked normal to me, with no extra words or signs. Maybe we needed to reboot the FSD or MCU computers? Maybe the navigation data was missing something like what to look for?

It would not recognize signs that we could read from a distance but were obscured by a truck while we passed them. It seems to need a fairly close and clear view. Perhaps only the B-pillar cameras are used?

So we could see it working as it displayed each speed limit sign, but there were so many exceptions that we couldn't rely on it, such as within construction zones. Of which there were many this time around. Most of those signs had additional words like "work zone", "when flashing", "fines doubled", or were not the standard white with black letters rectangle. Right when we needed help remembering the last speed limit we saw.
 

GoldenDog

New Member
Sep 30, 2020
1
2
Sackets Harbor
Similar problem up here in Upstate NY. In rural NY, speed limit signs are posted when entering a speed zone and upon leaving the zone, another sign saying ex "END XX MPH LIMIT". At that point the state speed limit (55 mph) is in effect. Autopilot/steer does not recognize the "END" sign and will not revert to the higher state limit. The work around as above is to turn off and reenter the road. It then defaults to the higher state limit. Hopefully it will be solved by next update. I suppose it needs to recognize "END".
end speed limit sign.jpeg
 
Sep 10, 2017
394
343
Buffalo NY
Similar problem up here in Upstate NY. In rural NY, speed limit signs are posted when entering a speed zone and upon leaving the zone, another sign saying ex "END XX MPH LIMIT". At that point the state speed limit (55 mph) is in effect. Autopilot/steer does not recognize the "END" sign and will not revert to the higher state limit. The work around as above is to turn off and reenter the road. It then defaults to the higher state limit. Hopefully it will be solved by next update. I suppose it needs to recognize "END". View attachment 593850

Rural WNY here, I know exactly what you’re saying about this. “It” needs to recognize a lot of things, in addition to this...
 

Denny_Camp

Member
Oct 4, 2019
36
77
Huntsville Alabama
My M3 also does not see (is blind) to any speed above 60. There are several roads in my area that are 65 in places. Any speed at or below is read with no problem. The 65mph signs are the same size, shape and font as the slower speeds, but they do not show up in the visualization, and are ignored for speed control when in autopilot. All the other signs show up just fine. On my roads, the 65 is usually proceeded by a stretch of 55mph. When I pass the 65, no visualization, and no change in speed, and max speed is +5 (60 mph). I have to come out of autopilot and just use cruise control to go the speed limit. I have sent several bug reports, but no resolution. So frustrating to not be able to use autopilot.
 

Denny_Camp

Member
Oct 4, 2019
36
77
Huntsville Alabama
My M3 also does not see (is blind) to any speed above 60. There are several roads in my area that are 65 in places. Any speed at or below is read with no problem. The 65mph signs are the same size, shape and font as the slower speeds, with no additional wording, but they do not show up in the visualization, and are ignored for speed control when in autopilot. All the other signs show up just fine. On my roads, the 65 is usually proceeded by a stretch of 55mph. When I pass the 65, no visualization, and no change in speed, and max speed is +5 (60 mph). I have to come out of autopilot and just use cruise control to go the speed limit. I have sent several bug reports, but no resolution. So frustrating to not be able to use autopilot.
 

tonybelding

Active Member
Aug 17, 2006
1,478
797
Hamilton, Texas
Incidentally, my car finally managed to read a 75 MPH sign today. I saw it flash past in the visualization and had a brief moment of hope before I glanced down at the dash to see what it had read… 15. The car thought the speed limit was 15 MPH.
 

Bet TSLA

Active Member
Dec 8, 2014
2,858
10,508
Cupertino, CA
I drove around a bunch of mountain roads near Lake Tahoe yesterday using 2020.40.3 in my Model 3. I'm not impressed with the new speed limit recognition. It erroneously paid attention to signs that said TRUCK SPEED LIMIT, and also END SPEED LIMIT, setting my limit based on those numbers. It also sometimes failed to pay attention to legitimate speed limit signs.

There were also quite a few sudden braking for nothing episodes, although they were all minor slowing rather than hard braking. That problem sure isn't gone yet.

Oh, one good thing. For the first time I saw autopilot reduce the speed in a town and then resume a higher speed after passing through, apparently setting the limit based on signs. I'd never seen it go up before.
 
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spokey

Member
Aug 8, 2020
610
235
Flagtown
I'm confused. I guess I'm setting stuff wrong but when I put on cruise control, it never goes up if the speed limit goes up. The signs on the display change and that seems to be working pretty well, but it doesn't change my max speed. Is there a setting that says "try to match the speed limit sign"?
 

Bet TSLA

Active Member
Dec 8, 2014
2,858
10,508
Cupertino, CA
I'm confused. I guess I'm setting stuff wrong but when I put on cruise control, it never goes up if the speed limit goes up. The signs on the display change and that seems to be working pretty well, but it doesn't change my max speed. Is there a setting that says "try to match the speed limit sign"?
No. And it never has before. This (with 2020.40.3) is the first time I've seen it increase.
 

cruiserlarry

Gadgetologist
Jan 24, 2017
283
348
Los Angeles, CA
Speed limit sign recognition was fine until 2020.40.3 for me...now, similar to some previous posts, it maintains a slower speed limit when it sees an "End Speed Limit XX" sign, or sometimes just keeps the lower street speed after entering a highway (although it eventually changes to the higher speed, it is not until several signs - definitely not Google data IMO).
 

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