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Discussion Starter #1
I've been battling with MB on this for some while and think that, with help from this forum, I have narrowed down where the problem lies.

The issue is the accuracy of Speed Sign Assist. My understanding of the way this should work is that in normal circumstances the speed symbol on the dash shows the speed given by the satnav data but is superceded by any speed signs that are observed by the camera. In this way there should always be the correct speed sign shown on the dash and when passing a de-restriction sign the appropriate speed should be shown.

From what others on this forum have said it seems that those who have the Advanced Nav pack this is exactly what happens but for those who have the std Nav they experience a number of malfunctions. In my case I find the following 'features'

1. Starting a new journey a speed symbol is only shown after a speed sign has been past.

2. Passing a de-restriction sign may result in this sign showing on dash for a while before going out OR a 60mph sign.

3. Speed symbols may go out at any time.

4. Incorrect speed symbols are shown although no sign with that speed has been passed

5. When entering a motorway the 70mph sign does not show for a couple of miles

Please help me with some comment on this. If you are experiencing similar issues or never experience these issues please reply saying whether you have the STD or advanced Nav.

Thanks in advance
 

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I only got the car ten days ago but have been extensively looking into this subject and have also read several of your forums posts on this. I have premium plus with driving assistance pack. Post Dec 2019 Augmented Navigation is standard in all premium pack and above; Traffic Sign Assist is included in premium plus pack. This is my understanding after extensive research :)

1. Speed Limit Assist and Traffic Sign Assist are two available functions on this and their functionality varies a little bit. Speed Limit Assist is available as standard while Traffic Sign Assist (superior version of the speed limit assist) is available for those who opted for Advanced Navigation Pack (before Dec 2019) or the premium plus pack (after Dec 2019).

2. Speed Limit Assist uses the camera alone and scans for speed limit signs (it uses the same camera used by Lane keeping assist) and if it doesn't find speed limit signs it doesn't display it.

3. Traffic Sign Assist uses camera for scanning speed limit sign and where it doesn't find speed limit sign it uses navigation data to complement the data. It also uses standard speed limits based on classification as dual carriageways, motorways, etc before the camera could scan for any speed limit signs. Traffic Sign Assist ensures that there is always a speed limit displayed in the dash irrespective of it scanning a sign or not.

4. Auto Adoption of speed limit for the cruise control is only available in cars with the Driving Assistance Pack. This functionality is called Active Speed Limit Assist. As long as you have driving assistance pack, I guess this functionality should work with either Speed Limit Assist or the Traffic Sign Assist (although post Dec 2019 you can buy driving assistance pack only with premium plus which means that you will have Traffic Sign Assist as part of premium plus if you opt for driving assistance pack).

I know the above details is quite a lot and confusing to digest but it should answer to all your questions in the forum on this subject over the past several months.

Based on the above, it appears you only have the 'Speed Limit Assist' and i guess that its working as intended for you. Others can add their experiences.
 

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Discussion Starter #3
Thank
I only got the car ten days ago but have been extensively looking into this subject and have also read several of your forums posts on this. I have premium plus with driving assistance pack. Post Dec 2019 Augmented Navigation is standard in all premium pack and above; Traffic Sign Assist is included in premium plus pack. This is my understanding after extensive research :)

1. Speed Limit Assist and Traffic Sign Assist are two available functions on this and their functionality varies a little bit. Speed Limit Assist is available as standard while Traffic Sign Assist (superior version of the speed limit assist) is available for those who opted for Advanced Navigation Pack (before Dec 2019) or the premium plus pack (after Dec 2019).

2. Speed Limit Assist uses the camera alone and scans for speed limit signs (it uses the same camera used by Lane keeping assist) and if it doesn't find speed limit signs it doesn't display it.

3. Traffic Sign Assist uses camera for scanning speed limit sign and where it doesn't find speed limit sign it uses navigation data to complement the data. It also uses standard speed limits based on classification as dual carriageways, motorways, etc before the camera could scan for any speed limit signs. Traffic Sign Assist ensures that there is always a speed limit displayed in the dash irrespective of it scanning a sign or not.

4. Auto Adoption of speed limit for the cruise control is only available in cars with the Driving Assistance Pack. This functionality is called Active Speed Limit Assist. As long as you have driving assistance pack, I guess this functionality should work with either Speed Limit Assist or the Traffic Sign Assist (although post Dec 2019 you can buy driving assistance pack only with premium plus which means that you will have Traffic Sign Assist as part of premium plus if you opt for driving assistance pack).

I know the above details is quite a lot and confusing to digest but it should answer to all your questions in the forum on this subject over the past several months.

Based on the above, it appears you only have the 'Speed Limit Assist' and i guess that its working as intended for you. Others can add their experiences.
Many thanks for your reply which I fully understand. However, regarding point 2 I do not believe this is correct. This is for 2 reasons, first the descriptions given by MB show that Speed Limit Assist should give the speed limit at all times, but perhaps more crusially there are times when SLA does give me a speed symbol when I haven't passed a sign, on motorways for instance, sometimes but not at other times a 60mph after a de-restriction sign or on other occasions a completely incorrect limit. I have also found that these incorrect speed symbols are consistent on a specific stretch of road but these incorrect symbols change with various map data updates. An example of this is a stretch of road near me where coming out of a 30mph limit the dash showed a de-restriction symbol which then changed back to 30mph, after a map update the de-restriction symbol goes out after 30 secs or so with no limit being shown.

I believe, but have been unable to corroborate, that those with Advanced Nav but no other packs the SLA works correctly, I also note that with Advanced Nav there is a speed symbol on the Nav screen as well as on the dash but don't know whether this is relevant or not.

MB are keen to tell me that all A Class work like this and therefore it is not a fault (a feature perhaps 😂) which is why I looking for feed back from as many others as possible so that I can form a picture.

Sorry this is long winded 😥
 

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As an aside, but you probably already know this, but Traffic Sign Assist also recognises other signs (eg: overtaking restrictions, No Entry), Speed Limit Assist only recognises circular speed signs?

Not sure if SLA recognises the "when wet" distinctions like you get in France though.

 

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Discussion Starter #5
Speed Limit Assist only recognises circular speed signs?
That's a reasonable assumption but it is smarter than that as it picks up over head gantry speed limits as well. I had assumed (always dangerous!) that SLA used the same technology as the TSA but just with a reduced data base of signs, seems logical but therefore probably totally incorrect 🤣
 

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Discussion Starter #6
3. Traffic Sign Assist uses camera for scanning speed limit sign and where it doesn't find speed limit sign it uses navigation data to complement the data. It also uses standard speed limits based on classification as dual carriageways, motorways, etc before the camera could scan for any speed limit signs. Traffic Sign Assist ensures that there is always a speed limit displayed in the dash irrespective of it scanning a sign or not.
Just re-reading you post, i've not picked up on this anywhere myself, if its correct it would explain a few things (but by no means all), could you point me to where you have read this
 

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Discussion Starter #7
I recognise that the video here is for the GLA and not the A Class but it does describe SLA which you might hope 🤣🤣🤣 would operate the same way on all vehicles.

I firmly believe that this is how SLA is intended to operate on the A Class and this view is supported by the fact that on some occasions a speed limit icon IS shown where there has been no limit sign on the road, if this is correct the issue would seem to be that speed limit data within the satnav application is either not complete or not being displayed correctly.

 

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Discussion Starter #8
Sadly I cannot find a description of SLA that is specific to the A Class but here is another description of it for another model
1585044226447.png
5054
 

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Sadly I cannot find a description of SLA that is specific to the A Class but here is another description of it for another model
View attachment 5054 View attachment 5054
This is a description from the previous generation car (as evident from COMMAND screen and not MBUX). Even the GLA example you give is from 2014 previous generation. From what i could understand the previous generation didn't have two varying functionalities. i,e. Speed Limit Assist and Traffic Sign Assist. They just had 'Speed Limit Assist' which was the previous generation equivalent of this generation's 'Traffic Sign Assist'.
 

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Just re-reading you post, i've not picked up on this anywhere myself, if its correct it would explain a few things (but by no means all), could you point me to where you have read this
From the Owner's Manual:

Speed Limit Assist: SLA detects speed limits with multi function camera and displays them in the instrument cluster and optionally in the head-up display. The camera also detects speed limits with a restriction indicated by an additional sign (e.g. when wet). The system detects stop signs thereby preventing engine from being switched off by the ECO start/stop function.

Traffic Sign Assist: TSA detects traffic signs with multi function camera. It assists you by displaying detected speed limits and overtaking restrictions in the instrument cluster and optionally in the head up display or central display. Since TSA also uses the data stored in the navigation system, it can update the display in the following situations without detecting traffic signs
  • when the vehicle changes road, e.g, slip road or motorway exit
  • when a village or town boundary which is stored in digital map is passed
If the system detects that you are driving onto a section of road in wrong direction, it triggers a warning. The camera also detects traffic signs with a restriction indicated by an additional sign (e.g when wet)

Hopefully the above information is useful. Again your car appears to have 'Speed Limit Assist' and i believe it is working as intended based on the above (i could be wrong).
 

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Discussion Starter #11
From the Owner's Manual:

Speed Limit Assist: SLA detects speed limits with multi function camera and displays them in the instrument cluster and optionally in the head-up display. The camera also detects speed limits with a restriction indicated by an additional sign (e.g. when wet). The system detects stop signs thereby preventing engine from being switched off by the ECO start/stop function.

Traffic Sign Assist: TSA detects traffic signs with multi function camera. It assists you by displaying detected speed limits and overtaking restrictions in the instrument cluster and optionally in the head up display or central display. Since TSA also uses the data stored in the navigation system, it can update the display in the following situations without detecting traffic signs
  • when the vehicle changes road, e.g, slip road or motorway exit
  • when a village or town boundary which is stored in digital map is passed
If the system detects that you are driving onto a section of road in wrong direction, it triggers a warning. The camera also detects traffic signs with a restriction indicated by an additional sign (e.g when wet)

Hopefully the above information is useful. Again your car appears to have 'Speed Limit Assist' and i believe it is working as intended based on the above (i could be wrong).
Thanks again for this, I had read the SLA above in the manual but as it was so slim on detail I hadn't given it much thought, I hadn't read the TSA description as I don't have it. I had been thinking that those with Advanced Nav had working SLA but perhaps all those who have Adanced nav also have TSA.

Much more feedback please from everyone, how does your SLA work and what packs do you have.

Going back to SLA, there is still ambiguity though because SLA does show limits where there has been no sign, on motorways for instance also on one hour long drive on B roads through lots of villages I found that sometimes when leaving a village I would get a de-restriction sign followed by no icon but at other times I would have de-restriction followed by 60mph all the way to the next village or just for part of the the way, so either it is not supposed to show a speed limit after a de-restriction in which case it is faulty or it is and its still faulty, whichever it certainly is not working as intended 🤣
 
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