new car has trouble recognizing speed limit signs

new car has trouble recognizing speed limit signs

I just got my 2017 Model S to replace my 2014 Model S. I have noticed my new Model S misses a lot of speed limit signs where my 2014 version picked them up very reliably. The new car has 2200 miles on it already so it's not like the system has not had time to learn. Anyone else seen this issue? If it matters, the new car has the full self drive hardware.

djlott | January 27, 2018 Model S doesn't do that yet. Stay tuned. Im in the same boat but this is my first MS so I don't know any different.

T35LA | January 27, 2018

Speed limit recognition in 2014 MS?
This feature was not enabled in AP 1 models nor it is with EAP - AP 2(.5) - yet.
Speed limits you are talking about are determined with GPS and navigation map system. | January 27, 2018

My understanding is AP1 visually identifies speed signs, but can screw up (reported that our highway 80 is misread as 80 mph). AP2 uses the GPS database for speed, and is accurate in most areas, but wrong in a few cases. Nether system is perfect. In 1 year with my AP2 S, I've never seen a GPS speed limit sign error (local streets and freeways), but other owners have reported issues with the database (i.e. wrong speed on a road). It may also depend if your in a rural area or in a non-USA country as to which method works better.

So those that get AP1 reading errors prefer the GPS system, and those that have AP2 with GPS database errors prefer sign reading. Likely some intelligent combination of both will be the final solution, but no idea when.

murphyS90D | January 27, 2018

My AP1 car has interpreted a 35 mph sign as an 85 mph sign.

TaoJones | January 27, 2018

AP1 for me was much more accurate than has been AP2. At first, AP1 had problems with school zone signs, but they fixed that. AP1's camera-based approach both recognized and reacted to physical speed limit signs. Another challenge, which I believe in part gave us the AP2 approach, is if a big truck is between you and a new speed limit sign.

AP2 relies upon an error-ridden database for speed limits. It's wrong a dozen times in a 10-mile radius here in SoCal and where it really gets fun is when it misses a zone in some rural area and then you're stuck at, say, 10mph below the limit (using AS) for however many miles until it updates in a new zone.

Neither system is perfect, but AP1 was far less error-prone. It's not just a SoCal thing - I've been in many states in this car as well.

My theory is that melding the 2 approaches (camera recognition with a database backup) would give us the best of both and a more suitable approach for FSD in general.

Otherwise, they''ll need to spend resources a) fixing the error-ridden db of today, and b) maintaining the db as speed limits can and do change with surprising frequency, either through state mandate/will of the people or just due to long-term construction projects (see the 605 as it approaches the 5 in East LA for a residual 45 mph zone *on the freeway*).

TaoJones | January 27, 2018

Addendum: a 45 mph zone, permanently signed (white/black sign large - not orange/black sign small), which by the way AP2 completely ignores. See error-ridden, and in this case an example that creates a safety/financial hazard not present with AP1.

pnajar | January 27, 2018

My AP1 P85D is better at seeing and accurately recognizing speed limit signs than I am. Without a doubt it reads speed limit signs. It’s not dependent on GPS or maps.

One road I drive has been going through renovation. As the speed limit changed to slow cars for construction my car recognized the new speed limit. There was no map nor software updates during the speed limit change.

murphyS90D | January 28, 2018

AP1 cars use the Mobileye chip. The Mobileye chip can read speed limit signs.

SO | January 28, 2018

AP2 will have to read speed limit signs for FSD. So it’s coming.....eventually.

bp | January 28, 2018

Middle of last year, Tesla changed providers for the speed limit data (possibly to TomTom).

Since then, at least for AP2 cars, the speed limit data has been much worse - and I haven't noticed any improvements since then.

For example, on a surface street near our house, the posted speed limit is 35 MPH. The speed limit database believes it is 55 MPH. So if I engage TACC to automatically set the speed, it immediately tries to get up to 60 MPH.

Some streets that used to have speed limit data (which was pretty accurate), now no data is there - so there isn't any speed limit shown on those streets.

And on some highways in the area, especially where there has been recent construction, the speed limit database thinks the speeds are 45 or 50 MPH in sections - when the posted speed limit is supposed to be 60 or 65 MPH. If the car is running under AutoSteer when it hits one of these sections, the car immediately slows down, because AutoSteer won't exceed the speed limit by more than 5 MPH on non-highway roads.

The inaccuracies of the speed limit data base, when it is being used to control the car's speed can create safety and legal problems for the driver - and it's up to the driver to realize this has happened and take over control of the car.

AP2 should eventually read speed limit signs (like AP1), but that's not enabled, as far as we know - though without any release notes from Tesla on what is and isn't working for AP2, we are all just guessing, and because these issues affect the safety of the car, Tesla really should provide more detailed information on what features of AP2 are working (as far as they know).

As for the bad speed limit data base, it's very possible this is a short term problem that will be resolved with the new navigation app. If NAV 2.0 is intended to support EAP/FSD, it will have to be using up-to-date map and speed limit data, in order to allow the software to fully control the car's driving.

jerrykham | January 28, 2018

In my area - CA Bay Area - my AP2 car using the database is correct about 80% of the time and wrong or doesn't even have the speed limit for the street at all and displays nothing about 20%. My street (been here for 8 years, but tract homes built on it only 3 years ago) doesn't show at all. The main street that connects us to the highway has a 45 MPH speed limit but the database says 40. This is common in the areas that I drive. Again it is about 80% correct. Definitely a good indicator or good guess but cannot rely on it to stay speeding ticket free.

kerryglittle | January 28, 2018

My AP1 has never misses a beat. I just wish the cruise control would adjust automatically to the different speeds in case I miss a sign. Sure it could be done some how. On the list. LOL

carlk | January 28, 2018

Eventually, and likely before FSD is fully implemented, everything will have to be geo-tagged. It's actually pretty easy for state and local governments to maintain a public accessable database with constantly updated speed and road work info.

p.c.mcavoy | January 28, 2018

@T35LA - I have a mid-2016 refresh MS90D with AP1. It very definitely does see speed limit signs. It has recognized temporary speed limits signs that were posted due to temporary road work that had only been up just a couple days. I've also seen it miss a sign where line of sight was blocked due to a truck in the outer lane on a road I drive daily where it regularly sees the sign and adjusts the speed limit correctly when line of sight is not obstructed.

TeslaKU | January 29, 2018

I have a mid-2017 Model S with AP2. AP2 does NOT read speed limit signs at all. There is a one mile surface street with two speed limit signs on it. One immediately and one about half way.

When turning on to the road, the speed limit in the console is blank. There is clearly a 30MPH sign. After about a quarter-of-a-mile, it comes up 40MPH. At the half mile mark you pass the second 30MPH speed limit sign, but the car still reads 40MPH. Clearly done from GPS/database and not visually.

bp | January 29, 2018

The speed limit database is so bad right now, I'd prefer an option to completely disable it - rather than risk having TACC set the speed 25 MPH over the posted speed limit (on a side street) or having AutoSteer abruptly slow down in the middle of 70+ MPH traffic. | January 29, 2018

@bp - To turn off speed limit, turn off TACC. Ok, I'm sure this is not what you want, but does the job for now.

Like all database errors, we all wish there was a reporting system to deal with errors. They could taking the AP1 sign reading data and making an analysis of likely database errors. I bet 95% of the issue could be corrected this way. Oh, well, I don't work for TomTom or Tesla.

Where are you located? I've yet to see a single error, traveling all around California. Perhaps some countries/states are worse than others. | January 29, 2018

Fixes: They could BE taking the AP1 sign reading data and MAKE a...

Uncle Paul | January 29, 2018

Tesla's do not perfectly read speed limit signs, but neither do people.
Often I loose track of speed limits. Either I am not paying attention, or a truck has blocked my view etc.

My X does speed limits pretty well, but not perfectly. Usually calculates the speed limits, just as I am passing a posted sign. Believe it does it by data base. Sometimes it is wrong, but it is always up to me to control my speed and not rely 100% on the car.

It seems to be getting better and better, and with each new update the auto pilot seems better able to control the car.

My expectations are pretty low for a car to completely drive itself. I think of it more of an assistant than a master.

If your expectations are for perfect self driving, it will always fall short.

Haggy | January 29, 2018

AP1 cars read speed limit signs from the time the hardware was added, which was weeks before Tesla even acknowledged that the hardware was there or announced autopilot. Back then it wasn't bad but it made more mistakes, such as interpreting a sign telling trucks to go 55 mph as the speed limit sign. These days it's pretty good. The only thing it can't do (at least on routes I've taken) is properly interpret a sign such as "End speed limit 45" which is another way of saying that the speed goes back to the prima facie speed limit. Why municipalities don't just use a "speed limit 55 mph" sign in those cases is what I don't get. I'm sure there's a reason and maybe somebody here knows what it is. But at least for now, even AP1 cars won't know what to do with that sign.

T35LA | January 30, 2018

Thank you. It's never too late to be educated ;-)

grdndzn | April 27, 2018

I have a 2018 Model S and have been surprised by how inaccurate the speed limit detection is. I live north of Chicago in a suburban / rural area and drive by speed limit signs that my Tesla misses over half the time. The information you are sharing on this blog is far more helpful than what my dealership is telling me. Thank you!

Bill_75D | April 27, 2018

Your 2018 is not detecting speed signs. It is using a database based on your GPS position. The database is hopelessly wrong frequently.

sr.smr | April 28, 2018

I have a 2017 with AP2 version 2018.16 and it does not report the accurate speed limit. I ignore it and set AP accordingly. Maybe the soon promised cross country FSD test means the car will achieve sign recognition and all of the other associated capabilities that we want.

cb500r | April 28, 2018

Currently programmed speed limit is such bad in Germany that I would agree to have it disabled. Sometimes it shows the right value, sometimes AP2 also slows down, sometimes it shows too high or too low.
Most critical situation I had was in a tunnel on a highway, where the car decided to rapidly slow down from 100km/h to 50km/h, as the tunnel was straight below a street of the city above.
Luckily the driver behind me was not overreacting and I was also fast in accelerating again...
Much better on 2018.10.4, by the way.

Peter C | March 12, 2019

From the European Model S manual (Dec 2018) "When you adjust the cruising speed based on the speed limit, the set speed does not change when the speed limit changes. You must pull the cruise control lever again to cruise at the new speed limit."

It also seems that TomTom simply don't update reported speed limit changes until they physically visit a location. I have 9 outstanding MapShare Reporter requests with them, all pending during the last 6 months.