Hello,

I usually drive with the cruise control on when in the highway. The system is nice enough to detect speed limits and adjust the car's speed.

There is this highway close to my home (tangential di Milano) that has speed limits specific for trucks. This particular sign is the same as a speed limit with the addition of a regulatory sign that specifies that the speed limit applies only to trucks.

In conclusion the speed limit signs alternate between 90km/h for cars and 70 km/h for trucks.

The GLS ignores the regulatory sign and suddenly slows down, then sees the sign for cars (90km/h) and accelerates, then again a speed limit for trucks comes and speed is down to 70km/h. This is annoying since cars do not expect my car to slow down all of a sudden ...

I tried to tell an Italian MB retail shop about this issue and they told me that the GLS computer did not record any anomaly so the car was fine ... no comment on this ...

Any one has a suggestion on how to report this to MB so that they can think about a fix ?

 

Strange, but I experienced that problem for the first time yesterday. Usually, the speed limit detection is right on, even recognizing reduced speeds in work zones. Yesterday, on a 200 mile trip on the interstate, the 580 reduced its speed from 75 to 55 three times and once cut the speed to 40. Each time that happened, I had just passed a speed limit sign that announced that the maximum speed is 70 and the minimum speed is 40. The speed limit signs in my state look just like the graphic speed limit sign in the HUD, so strange signage is not the problem. In addition, a warning on the instrument screen has been coming on repeatedly in the last few weeks that says "camera view unavailable." And there are no bugs on the cameras.

 

Hi,

could it be that camera unavailable was due to adverse weather conditions like fog and / or rain ?

 

Nope. There wasn't a cloud in the sky on a 400 mile (200 each way) trip yesterday. It has been going on for several weeks now, even on short trips. Can you imagine what would happen if Boeing built its 737 series airplanes with this many software bugs?

 

This system is nowhere near accurate enough to rely on. I would never use it.

 

I have had similar problems, including mine picking up the lower speed limit signs on off-ramps (when I’m not getting off). There is one road I drive regularly that is 90 or 100 most of the time, and in two different spots it randomly starts slowing down (I haven’t noticed what it is slowing to - too dangerous with cars behind me to let it keep slowing down). Very annoying, but I attribute it to the camera mis-seeing something,

 

Piggybacking off your experience, I entered the State Farm safe drivers program. I was penalized for speeding when accelerating when leaving a 35 MPH zone ramp and speeding up to enter the 70 MPH expressway. Go figure.

 

I don't think this is a bug, this is by design and speaks to broader, difficult hurdles that need to be overcome as we inch toward autonomous vehicles.

MB's software likely recognizes both speed limits and can probably distinguish which sign is applicable to you, but there are a number of more nuanced cases where only drivers can make the call. For example, I've seen plenty of signs that say something along the lines of X MPH WHEN WORKERS PRESENT Y MPH ALL OTHER TIMES. Or two speed limit signs stacked on top of each other -- the normal speed limit followed by the school zone limit. The technology just isn't mature enough to distinguish between "workers" and people standing on the side of the road, or determining if school is in or out of session (is today a half-day? does Thanksgiving break start on Mon or Tue?). So instead of guessing, the car plays it safe and goes with the lower limit.

This isn't just a MB thing, and it's not just road signs. When driving you're making one judgement call after another, both consciously and subconsciously. Manufacturers are spending billions trying to figure out how to solve for that. The technology is evolving rapidly but it's not even close to being there.

 

Totally agree with @neetorama . One cannot rely 100% on tech. Otherwise would could all just read a book while driving. I believe this happens to most of us. I have become accustomed to it, and simply just hit the gas and reset cruise control speed. I have also experienced the opposite - while driving over a bridge with a stated 55MPH limit, my GLE suddenly accelerated to 80MPH. I looked at the HUD, and it was displaying 80MPH. Very odd. I never reported it to MB cause they probably wouldn't be able to duplicate it.

 

IMHO, software/systems where a malfunction can lead to an accident are totally unacceptable. How about a brake or gas pedal that works correctly once in a while only?

 

Better to turn off the feature. You don't want the headache of getting rear ended because the car thought it was reading the right speed limit for your path!

 

The automatic speed limit adoption doesn't make a whole lot of sense in the US. I used it in Europe where speed limits change frequently and are strictly enforced. It's very common on the Autobahn for the speed limit to be lowered to 100 km/h, then back up to 120/130 km/h, then unlimited in parts if you are Germany and then back down again and again. Even so, one of the annoying issues in Europe is that lorries (semi trucks for the Americans) have a small speed limit sign sticker on the back with the number 80. It's there to let you know that they are not allowed to drive faster than 80 km/h legally. Unfortunately, the speed limit recognition thinks that's a real speed limit sign and adopts 80 km/h as the speed limit, so now suddenly the car isn't accelerating after changing lanes.

As was said in an older post above. These systems have real world limitations. They follow their programming but lack the intuition and judgment of a human. Getting upset when it recognizes the wrong speed limit is simply a waste of energy. Use it for what it is and if it gets the speed limit wrong at times, just move on. Turning off the automatic adoption of the speed limit is the best course of action to make it less annoying when it happens. I don't even think about it anymore. It's nice to see the speed limit in the instrument cluster, but I don't let it dictate my speed.

In Europe, new cars now must sound a warning if you exceed the detected speed limit. I experienced this most recently in a rental car last October while traveling in Germany and Switzerland. The thing was constantly beeping at me as it recognized the wrong speed limits or if I only went 1 km/h over the detected speed limit. One of the dumbest mandates ever. You are allowed to turn it off, but it's mandatory for it to turn back on between engine starts, so every damn time I had to turn it off to stop being yelled at for going 1 km/h over the speed limit. Stupid, just stupid!

 

Maybe Mercedes already found the fix, try asking the dealer or any Mercedes licensed workshop to try a software update for your camera and maybe MBUX/Comand as the Maps works together with the Camera for predicting the signs

 

There’s no “fix” since it’s working as intended. The only solution is to turn the feature off, which many of us have already done!

 

It's not perfect, but even so it is worth using. Occasionally it can introduce errors and risk, so you do need to remain vigilant in monitoring it. Plus, my wife has neuropathy from chemo, and it is a godsend to her.

 

My G550 has sign reading capability, but not automatic speed adjust. When I drive into the local town, the highway speed is 45 mph. Within this 45 mph zone, there a speed limit sign advising that the maximum speed within the town is 25 mph. My car reads this sign and then tells me I'm speeding while l'm driving 40 mph in a 45 mph zone. Until these speed limit systems are able to differentiate such signs, they are worthless and dangerous.

 

Yeah, the biggest issue with these types of systems is that traffic signs etc. are made for the humans behind the steering wheels and not the machines. Even self-driving cars have to be trained on recognizing traffic lights, instead of communicating with the traffic lights. Particularly in the US, there isn't really a standard as to what additional text can be below a traffic sign. So the example above where somebody decides to put a speed limit sign up with text below saying that this will apply once you enter the town, will simply not be correctly interpreted unless there's AI that reads the text and understands what it says and then knows the speed limit doesn't apply yet. There are tons of signs like that in the US, where a text below says it only applies during a certain time of the day, or only during a full moon or what not.

There's much less of that in Europe and things are more standardized. For example in Europe you'll see speed limit signs that only apply when the road is wet. You see those particularly in Germany, where unrestricted Autobahn sections have a speed limit when it rains. I was amazed that it recognized those and combined the information with the rain sensor to know if the speed limit applies or not. But again, that sign is standardized. It doesn't just have text, but also visually shows a car with wet road surface. I've come to realize that these systems work much better in Europe than they do in North America. There are much fewer signs that it recognizes in North America compared to Europe. In Europe it even recognizes upcoming speed limits when you are about to exit a highway. It shows the current speed limit and the upcoming speed limit next to it. I've never seen this working in the US.

I've always thought it was wild how some traffic signs in the US have a bunch of text that you have to read while driving past them to know what's going. Evidence shows that many people don't read those texts. Near my house, there's an intersection where left turns are prohibited during commute hours, but are allowed before and after. Every day there's a honking fest going on when somebody tries to legally turn left during the permitted hours. The drivers behind them only see the no left turn sign, but don't bother reading what it says below and get upset if their lane isn't moving and honk like mad at the person who is simply attempting a legal left turn. Not to mention that many of them probably don't even have good enough eyesight to read it from farther away. TBH, the font is too small even for somebody with 20/20 vision to see what it says from a block away. Also, in the US you can get a driver license w/o speaking and understanding a word of English. The DMV lets you take the driving test in whatever language you want.

 

My 2021 is able to differentiate reliably, unless I'm driving into a sunset. Then I get a pop-up that says something like "functions limited."
If yours is confused, you might need a camera recalibration.

All road signs on US roads are standardized. There's a standard called "Manual on Uniform Traffic Control Devices (MUTCD)." Municipalities are required to use it too. Most of them comply.

It also specifies such things as minimum distance for placement of a sign warning about an upcoming speed reduction, and other things such as only allowing a 15mph reduction in speed, per sign. That's why you see a speed reduction or two preceding a yellow corner speed advisory sign.

 

Yeah, well unfortunately they do. Boeing went from an engineering firm to a bean counting firm. NTSB is not happy.

 

This is the type of conditional speed limit sign I was referring to. These are posted in zones with higher speed limits as an advance warning, but are processed immediately by the car's sign reading system.

 

I didn't mean to say that the US doesn't have a standard at all, but examples like the above is what I'm talking about. There is actually an international standard, known as the Vienna Convention on Road Signs and Signals. Most of the world follows it, so the signs are standardized across borders. There are some countries such as Mexico and parts of South America that have signed it, but never ratified it. The US never even signed it just like they failed to adopt the metric system that most of the world uses. Based on my personal experience with my own car driving in Europe and North America, the traffic sign recognition seems to work far better in countries that follow the internal standard vs. one-off standards like the US. Seems the developers spent most of their time on implementing the international standard correctly and the US is an afterthought.

 

That's a good example, and the next town to mine is surrounded by those signs. My 2020 GLE has never mistaken it for an actual speed limit. IDK what the difference would be, other than the onboard map overriding a non-spec sign.
It also identifies school zones correctly, showing both in my Headup display. I kind of think the onboard Maps is influencing that, because the school zone sign disappears at the same point the oncoming traffic School Zone is positioned, a block before the normal speed limit sign is positioned.

I don't use the settings that automatically adjusts speed, though, so I can't report on that.

 

But does it correctly show the speed limit in town if no other speed limit is posted after one of these?

 

Yes, the "20 unless otherwise posted" sign is in a 35 mph area and the headup display shows 35.
That's another reason I think there's interaction with NAV.

 

I was asking the opposite. If you aren't driving in the 35 mph zone, does it show 20 mph? Or asked differently, if there isn't a 35 mph speed limit sign, does it know the speed limit is 20 mph?