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Highway speed limit issue with 40.4 update

psteveo

Member
Sep 3, 2019
10
1
Chicago
Is anybody else having an issue with the speed limit the car recognizes on highways? With the car now utilizing the cameras to detect speed limit signs, it doesn't appear to be able to differentiate between the actual speed limit and other speed limit signs. For example, there are minimum speed limit signs and different speed limits for trucks, buses, etc. It seems to treat all of them as if they are the actual speed limit. This is a problem when going off auto steer and back on, because it will then use the wrong speed limit.
 
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Twiglett

Single pedal driver
Oct 3, 2014
3,220
3,459
Austin
I've found 40.4 to be significantly better than the previous versions. 40.3 was horrible, with extra BT/USB bugs thrown in for good measure.
The version prior to that was even worse for speed limits.
Thankfully it will get better though and in a month or two will be much better.
 

PianoAl

Active Member
Dec 15, 2019
1,033
696
Far Northern California
I've posted about this. I've found that a sign like this:

truck-speed-limit-sign.jpg


does not trigger the car to change to the incorrect limit.

However, a sign like this does:

sign-jpg.590241


On a divided highway with controlled access, it doesn't matter, because the car doesn't limit the speed, but on a road such as the above, it screws up the autopilot (because you have to press the accelerator, you need watch your speed, and the car won't brake.
 
I have observed the speed limit sign detection works extremely well. Sometimes the signs are obstructed from view, and in those cases the car does not pick up the proper speed. Also at night, with high beams on, the car sometimes can’t read the sign because of the reflection from the high beams. I conducted a very unscientific experiment the other night using high beams on then off several times while passing a speed limit sign (that was changing the current limit) and the correlation with high beams and lack of change was very high.
 
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psteveo

Member
Sep 3, 2019
10
1
Chicago
I have observed the speed limit sign detection works extremely well. Sometimes the signs are obstructed from view, and in those cases the car does not pick up the proper speed. Also at night, with high beams on, the car sometimes can’t read the sign because of the reflection from the high beams. I conducted a very unscientific experiment the other night using high beams on then off several times while passing a speed limit sign (that was changing the current limit) and the correlation with high beams and lack of change was very high.

It can see and read speed limit signs well. That isn’t the issue. The issue is that it doesn’t know the difference between the actual speed limit signs and other speed limit signs, such as for trucks, buses, etc. So it incorrectly changes the speed limit when it sees those signs.
 

electrongeek

Metrology Fanboy
Nov 1, 2019
69
74
Maine
I have found that while it actually reads a speed limit sign, as it shows up correctly in the UI, it doesn't change its speed limit until it sees a second identical speed limit sign a short way down the road. This only seems to happen in the instance when there are two same speed limit signs in fairly close succession.
 
I just did a 4400 mile road trip from San Diego to Chicago (along route 66) and back (along I-80) and MAN the stupid speed limit detector really wasn't working worth a crap.

To be fair, most of the time it saw speed limit signs correctly, including unexpected road construction limits. However quite often in Arizona, New Mexico and Texas, I would be driving along and pass a "65" speed limit sign, yet the car would act like it didn't see it and limit me to 55. Usually it shows the sign on the display, but for these it was like they weren't even there.

Similarly, in states I saw there are several signs and it just seem to confuse the car to no end. "Speed limit 70," "minimum speed 45," "truck speed limit 55." I forget exactly where I was but these three signs posted one after the other caused my car to think the speed limit was 70, then 10 yards later it was 45, then 10 yards later it was 55. I watched the screen in horror. lol.

So yeah, learned my lesson to be mindful of the speed limit detector: it doesn't always work, and our roadways can really be confusing!
 

Randy Spencer

Supercharger Hunter
Mar 31, 2016
3,993
4,298
Alameda, CA
I find that if I am in the lane closest to the speed limit sign it can tell the sign for a truck limit and the sign for the trailer limit and they are ignored, but in the second lane or further away it picks them up as the new speed limit.

I have to imagine all this is fixed in v11 and they are just not making any real changes to the current software as they are trying to get the to the next major release as soon as possible. It's probably what is holding up the release of the S/X
 

PianoAl

Active Member
Dec 15, 2019
1,033
696
Far Northern California
I find that if I am in the lane closest to the speed limit sign it can tell the sign for a truck limit and the sign for the trailer limit and they are ignored, but in the second lane or further away it picks them up as the new speed limit.

I've been experimenting, and I think that driving slower past the signs helps the car recognize them for what they are.

Related, there is a curve in a two lane road on which, at 55 MPH, the car touches the center line. At 50, it is fine. My tentative theory is that the car's computer is overloaded such that a slower speed allows it to better complete calculations.
 

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