How does the car know what the speed limit is?

[jabloomf1230]

It's valuable data, so better to let private companies collect it and make a profit than the gov't to spend LOTS of tax dollars collecting it in the least efficient way.

I figured someone would write this. If you read my previous posts, I wrote that probably every State DOT has an ArcGIS coverage of its roads. The government is already doing most of the work. Private industry is just co-opting the data.

 

[Knightshade]

I know, legislation is needed. It might have to condition federal highway aid on participation in a new program.

There's a 5-step test to judge constitutionality of conditioning funding like that it'd need to pass in the courts though- I'm not sure "force all state and local governments to report up all speed limits to a federal database" is going to pass several of em even if anybody in congress was interested in trying it.

I mentioned fixing NICS earlier because that's probably an easier lift to get through the courts from a general welfare perspective and they've not even been able to get that done.

 

[Z_Lynx]

There's a 25 mph road at the edge of town. At one point going south, it switches to 30 mph and stays that way for the 4 or 5 blocks left on that road. There are absolutely no signs that would indicate it should be 30 mph.

In addition, if you enter the road to go north, it is 25 mph and stays that way. The only signs on this road indicate 25 mph both north and south. Very annoying.

 

[jabloomf1230]

There's a 25 mph road at the edge of town. At one point going south, it switches to 30 mph and stays that way for the 4 or 5 blocks left on that road. There are absolutely no signs that would indicate it should be 30 mph.

In addition, if you enter the road to go north, it is 25 mph and stays that way. The only signs on this road indicate 25 mph both north and south. Very annoying.

Take a look at this thread:

FD Beta : TomTom Map, Roundabouts and the Speedlimit

TL;DR : Let us use this thread to talk about map changes that could potentially make FSD Beta behave better Thanks to the post below by @MP3Mike I discovered an interesting little fact. Tesla probably does use TomTom maps rather than Google or OpenStreet for city FSD Beta driving. I've two...

teslamotorsclub.com

You can look at the road segment in TomTom to see what the speed limit is. Alternatively, what road is this?

 

[Gasaraki]

WINNER WINNER CHICKEN DINNER!

It does both.

Not anymore. It hasn't been this way for a while now. All it uses is vision to tell the speed. That is why it gets it wrong more often then before because it can't read the special speed limit signs like '30 Ends'. It keeps thinking that means it's 30MPH limit.

 

[Z_Lynx]

I don't have access to TomTom. If you could check, that would be great.

This is Carlton Road, south end, terminating at Monticello Avenue, Charlottesville, VA. If you use the link below, you can expand it to see the north end. I think most of the section you see has 30mph going south, 25 mph going north. I could find a precise point where the car says it's 30 mph if you need it but it would take a while to go through my video.

Google Maps

Find local businesses, view maps and get driving directions in Google Maps.

www.google.com

EDIT - I see now that Carlton takes a turn - and if you are going straight, it is Meade avenue.

I actually found the clip I had of the transition and location. I'll see if I can get them up before the edit window closes.
Below I dropped a pin in the lower left quadrant. There is a sign in front of the building that you can see in the video stills. The sign is seen at 25mph and the other at 30mph. The small sign coming up is a no parking sign, I believe.

 

[Knightshade]

Not anymore. It hasn't been this way for a while now. All it uses is vision to tell the speed. That is why it gets it wrong more often then before because it can't read the special speed limit signs like '30 Ends'. It keeps thinking that means it's 30MPH limit.

This is absolutely untrue, it still uses both.

How else would it have speed limits listed for roads where you didn't pass a sign yet?

It will use vision WHEN AVAILABLE (including misunderstanding conditional speed limit signs) but still uses maps otherwise.

As an example there's a local road I turn onto about 90% of the time I leave my house- after the turn you don't pass a posted speed limit sign for at least a mile... that entire mile it lists 45 mph as the speed limit based on map data. (Hilariously, this is actually wrong, the limit there is 55... but since the car is relying on old map data it doesn't know that until it passes the 55 mph sign a mile later and bumps it up)


(and the previous road I exit my driveway onto that I'm turning to get to the above road it has as 25, even though that's higher too- but there's no sign for it to read there, so it's not just carrying that 45 over from the previous road- it's map data)

 

[holmgang]

from observation, Tesla prioritizes recognition of speed signs, and then falls back to mapped data.

Which brings me to a pet peeves. Why is road mapping data like a game of whack-a-mole? Shouldn't each country maintain an online database of road mapping data and publish any changes monthly? Right now, vehicles rely on private mapping vendors to somehow figure out what the government is doing. Imagine what would happen if the government decided to opt out of aviation mapping?

easy answer to this is:
(1a) because it's government
(1b) there's no incentive for the government to do this

 

[Camway]

Which brings me to a pet peeves. Why is road mapping data like a game of whack-a-mole? Shouldn't each country maintain an online database of road mapping data and publish any changes monthly? Right now, vehicles rely on private mapping vendors to somehow figure out what the government is doing. Imagine what would happen if the government decided to opt out of aviation mapping?

I'm a transportation engineer who works a lot with the Colorado DOT. They maintain a GIS database of all the speed limit signs on US and state highways, and I'd imagine that almost all the other state DOTs do as well. Roadside signs get knocked over or otherwise damaged pretty frequently and the DOT uses the database to replace them. My guess as to why they are reluctant to share this data with the private mapping vendors is that legally, only the posted speed limit is enforceable. So if a sign gets knocked over or a temporary work zone is in place, a car relying only on map data for speed limits could be going much faster than what is legal at that point in time. All that being said, Colorado DOT's GIS database is publicly viewable so any private vendor could theoretically pull the speed limit data and use it in their mapping system.

 

[Camway]

Relies heavily on vision in my experience. We have several speed limit changes identified as you see in the photo. Not only is it just the dumbest thing but it means the car does not understand what the new speed is limit when passing this. Frankly, humans don’t either. No idea how this passes DOT guidelines.

View attachment 759210

Agree that this should have never been allowed. Throughout the US, all state DOTs and municipalities are obliged to meet the same federal requirements on signing, the Manual on Uniform Traffic Control Devices (MUTCD). This sign assembly is definitely not consistent with the MUTCD and is really dangerous with cars like a Tesla that read those signs, but can't recognize the END. You should reach out to whomever maintains this road (state DOT, county, or town/city) and report this to them.

 

[jabloomf1230]

@Z_Lynx ,

Neither Carlton Rd. nor Meade Ave. have any speed limit tags in TomTom. What's also interesting is that Monticello Ave. has overlapping nodes with with either 25 or 35 mph speed limits. This could caused by a bug on the TomTom website. Maybe @EVNow could confirm.

I'm going to check OSM next.

 

[jabloomf1230]

@Z_Lynx ,

Neither Carlton Rd. nor Meade Ave. have any speed limit tags in TomTom. What's also interesting is that Monticello Ave. has overlapping nodes with with either 25 or 35 mph speed limits. This could caused by a bug on the TomTom website. Maybe @EVNow could confirm.

I'm going to check OSM next.

On Open Street Maps, Carlton Road is 25 mph except for a small segment south of the intersection with Carlton Avenue. That segment has no speed limit in OSM. Does that help?

 

[RSpanner]

Hell if I know, but the last ICE car, a 2017 Audi used the Nav system and info from maps to post the speed limits.

 

[Z_Lynx]

Thanks for looking, jabloomf123!

VDOT (Virginia Department of Transportation) has an online gis to show what posted speeds are but it doesn't have anything for the city of Charlottesville, which is apparent when you zoom in that uses color coded solid and dashed lines to indicate speed. Looking in the county, it appears to be somewhat spotty:

VDOT Speed Limits Map

Map showing Posted Speed Limits of cars and trucks on VDOT maintained roadways in the Commonwealth of Virginia.

virginiaroads-vdot.opendata.arcgis.com

The librarian at VDOT could not find any info on that road and her manager suggested I contact the city's traffic engineer. I will see what he has to say tomorrow. I should be able to find out something.

Regarding Open Street Maps and the Carlton Rd/Carlton Av instersection, since the change to 30mph starts a block north of that intersection, not sure it is involved.

Monticello Ave. is 35mph going into the city and later drops to 25mph.

 

[valaeyron]

It's valuable data, so better to let private companies collect it and make a profit than the gov't to spend LOTS of tax dollars collecting it in the least efficient way.

Exactly. We'll all pay somehow...??

Because, you know, profits are the entire purpose and sole measure of any endeavor.

Because, you know, there aren't tons of situations in which government does do a good job including collecting information efficiently.

Because government does it, it must be bad.

 

[FLMan]

I'm almost certain it uses both and prefers vision over the database, but if given no visible signal it defaults to the database.

We have a highway here that recently went from 65 to 70 but the signs are off the road a bit. When driving past them in the right lane the speed limit correctly updates in the car to 70, but when driving past them in the left lane the speed limit incorrectly shows 65 through that section of the road.

 

[father_of_6]

Because, you know, there aren't tons of situations in which government does do a good job including collecting information efficiently.

True.

 

[BigNick]

Which government?

Some speed limits are set by the federal government- but relatively few.

Some are set by state governments, there's 50 different ones.

Some are set by counties or municipalities, of which there are tens of thousands


And that's just in the US.

List of townships in Pennsylvania - Wikipedia

en.wikipedia.org

There's 1550 local governments right there.
That doesn't count the 67 counties which have their own governmental structure, or the entire state (officially, the Commonwealth of Pennsylvania.)
It also excludes towns, boroughs and cities which are their own entity and not part of a township.
The townships don't all have distinct names. With Ben Franklin being a popular dude in these parts, 16 different counties in PA have a Franklin Township somewhere.

 

[holmgang]

Because, you know, there aren't tons of situations in which government does do a good job including collecting information efficiently.

such as?

 

[Petermcg]

The Asheboro bypass here in NC has been open since December 2020. It’s a clearly marked, 4 lane, 65 mph, divided highway (looks like any interstate) that my M3 thinks is a 45 mph country road. I’ve taken great care to drive cleanly past the speed limit signs but the car ignores them. It drives me crazy that I have to keep my foot on the accelerator in order to use autopilot above 45 through this whole stretch of road.

I know, first world problems, right?