FSD v14.2.2.4 (Update 2025.45.9) happening now

[M0unt41nm4n]

Looks to me like those back roads are missing the GIS speed limit data. Tesla uses a whole bunch of aggregated state and federal databases for speed limits, so if roads are missing they have to fall back to surrounding traffic context awareness, last know good speed limits, etc. It's a complex algorithm, but basically they aren't allowing FSD to just simply read road signs and obey them as gospel (yet).

And it's not as easy as flipping a switch either. These types of systems are extremely hardened, and it's not that difficult to introduce REALLY bad errors; say for instance, how do you ensure FSD doesn't obey a sign placed by a prankster for 99 mph on a 4 lane avenue? or 1 mph in a neighborhood?

https://www.arcgis.com/apps/mapviewer/index.html?webmap=815ead7b87bb4d09872707495205445c

I know that in Moab and Durango, there are signs that say "25" or "35" "within the town of XYZ unless otherwise stated". My CT seems to default to that and I assume that is what comes from the GIS data. However from the Tesla notes from 2020.40.3:

https://www.notateslaapp.com/software-updates/version/2020.40.3/release-notes

it states the following:

Speed Assist now leverages your car's cameras to detect speed limit signs to improve the accuracy of speed limit data on local roads. Detected speed limit signs will be displayed in the driving visualization and used to set the associated Speed Limit Warning. As usual, to adjust Speed Assist settings, tap Controls > Autopilot > Speed Limit.

Speed Assist now leverages your car's cameras to detect speed limit signs to improve the accuracy of speed limit data on local roads. As usual, to adjust Speed Assist settings, tap Controls > Autopilot > Speed Limit.

As I stated before, when I go through construction zones that have temporary speed limit signs, the CT recognizes them and it changes the speed, exactly as stated above. I am surprised that you haven't noticed that as it was one of the first things I thought was cool when driving around. Like you, I thought maybe it was a database, but these construction zones seemed to just change the speed when I passed the signs and I knew there was no way these were listed in a database and updated to the vehicle. Believe it or not, my late model Ford does this too. I don't know if they marry it up to public construction info (like in Waze or other mapping software recognizing this) or what. But I do know it changes with temporary signs. This again may be why the OHV speed limit is being used rather than the regular vehicle limit. You must admit the sign does look uncanny like the standard and the CT seems to just pick one.

That said, it would be an interesting experiment to print a fake speed sign and see if the CT notices it. I am sure there may be some general boundaries ... like choosing speeds in increments of 5 and need to be within a specific range.

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[SCTesla]

That said, it would be an interesting experiment to print a fake speed sign and see if the CT notices it. I am sure there may be some general boundaries ... like choosing speeds in increments of 5 and need to be within a specific range.

There is a YT video where DirtyTesla did this. It picks most up, but not all.

 

[M0unt41nm4n]

There is a YT video where DirtyTesla did this. It picks most up, but not all.

Found it... pasting it here for those who are interested:

 

[REM]

I know that in Moab and Durango, there are signs that say "25" or "35" "within the town of XYZ unless otherwise stated". My CT seems to default to that and I assume that is what comes from the GIS data. However from the Tesla notes from 2020.40.3:

https://www.notateslaapp.com/software-updates/version/2020.40.3/release-notes

it states the following:

As I stated before, when I go through construction zones that have temporary speed limit signs, the CT recognizes them and it changes the speed, exactly as stated above. I am surprised that you haven't noticed that as it was one of the first things I thought was cool when driving around. Like you, I thought maybe it was a database, but these construction zones seemed to just change the speed when I passed the signs and I knew there was no way these were listed in a database and updated to the vehicle. Believe it or not, my late model Ford does this too. I don't know if they marry it up to public construction info (like in Waze or other mapping software recognizing this) or what. But I do know it changes with temporary signs. This again may be why the OHV speed limit is being used rather than the regular vehicle limit. You must admit the sign does look uncanny like the standard and the CT seems to just pick one.

That said, it would be an interesting experiment to print a fake speed sign and see if the CT notices it. I am sure there may be some general boundaries ... like choosing speeds in increments of 5 and need to be within a specific range.

interesting indeed! The speed limit portion of the NN puts a lot more weight into speed limit signs around temporary construction signs for sure, so we should expect to see those signs obeyed more often than others.

Same goes for school zones.

 

[PungoteagueDave]

I know that in Moab and Durango, there are signs that say "25" or "35" "within the town of XYZ unless otherwise stated". My CT seems to default to that and I assume that is what comes from the GIS data. However from the Tesla notes from 2020.40.3:

https://www.notateslaapp.com/software-updates/version/2020.40.3/release-notes

it states the following:



As I stated before, when I go through construction zones that have temporary speed limit signs, the CT recognizes them and it changes the speed, exactly as stated above. I am surprised that you haven't noticed that as it was one of the first things I thought was cool when driving around. Like you, I thought maybe it was a database, but these construction zones seemed to just change the speed when I passed the signs and I knew there was no way these were listed in a database and updated to the vehicle. Believe it or not, my late model Ford does this too. I don't know if they marry it up to public construction info (like in Waze or other mapping software recognizing this) or what. But I do know it changes with temporary signs. This again may be why the OHV speed limit is being used rather than the regular vehicle limit. You must admit the sign does look uncanny like the standard and the CT seems to just pick one.

That said, it would be an interesting experiment to print a fake speed sign and see if the CT notices it. I am sure there may be some general boundaries ... like choosing speeds in increments of 5 and need to be within a specific range.

My speed limit signs are technically fake - I have a 1.1 mile-long driveway at my farm, that is a private road per maps, but FSD has always been able to navigate it to the house, including two dogleg turns. It is improved gravel (tar & chip). The signs were made professionally by the same people who make state and county signs. Both of our Teslas read the signs, as did two prior Teslas in the AP days, but nowhere near as consistently as AP did it. Today's FSD ignores the "15" and tries to drive 40 - while AP on our '15 P85D and '19 MX did respond to the "posted' limit.

This is my sign proving that Teslas read signs.

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