Speed signs on dual carriageway

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Techno
Posts: 37
Joined: Fri Nov 09, 2018 4:49 pm
Location: Norfolk

Speed signs on dual carriageway

Post by Techno » Mon Mar 18, 2019 7:14 pm

Has anyone else found that on dual carriageways the speed on the sat nav often appears as 60mph. I am not sure if I have caused a problem by turning on Traffic Sign Recognition, or the base map data is incorrect.
TSR seems great on other roads so I am a little baffled by this.
”Becca” is a Rhodium Grey 2.0tsi 4drive DSG XCELLENCE Lux
Additional sunroof and spare wheel. TSR enabled by ODBeleven.
Ordered early December 18 collected 1/3/19


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Paul.Cambs
Posts: 173
Joined: Wed Jun 20, 2018 10:14 am
Location: Cambridgeshire

Re: Speed signs on dual carriageway

Post by Paul.Cambs » Mon Mar 18, 2019 7:58 pm

I have this occasional, on same stretches of roads, I think it picks up something I don't notice, possible on/near slips roads.
I think it notices a lot more than you think, I also see it say 60 when on slip road and change to 70 as soon as I cross on to main carriageway but there was no sign I could see.
'Samantha' is a Feb-2018 Samoa FR 2.0 TSi 4Drive DSG
19" Wheels | KESSY | Power Tailgate | Adaptive Cruise | Top View Camera | Seat Sound
Convenience Pack | Winter Pack | Advanced Comfort and Driving Plus Pack | Heated Front Screen


Techno
Posts: 37
Joined: Fri Nov 09, 2018 4:49 pm
Location: Norfolk

Re: Speed signs on dual carriageway

Post by Techno » Mon Mar 18, 2019 8:43 pm

Thanks again Paul. I drove from Norwich to Milton Keynes this morning and noticed it a lot. A47, A11 and A421 all did it. No problem in Cambs as the dual carriageway is mostly 40! ;-)

I think the sliproad 60 to dual 70 is in the maps.
”Becca” is a Rhodium Grey 2.0tsi 4drive DSG XCELLENCE Lux
Additional sunroof and spare wheel. TSR enabled by ODBeleven.
Ordered early December 18 collected 1/3/19


aggie2347
Posts: 27
Joined: Sun Apr 22, 2018 8:30 pm

Re: Speed signs on dual carriageway

Post by aggie2347 » Sat Apr 13, 2019 11:49 pm

Can anybody tell me whether or not the attached picture is in fact the camera behind the windscreen that detects traffic signs before I try and activate it with my VCDS cable.

20190411_121557.jpg



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pch
Posts: 134
Joined: Sun Jan 22, 2017 8:05 pm
Location: Dublin, Ireland

Re: Speed signs on dual carriageway

Post by pch » Sun Apr 14, 2019 10:32 am

For me it doesn't look like a 'multifunction camera' which is used for lane assist and traffic sign recognition.
In my Ateca it's located in the middle with a field of view in triangular shape.

See pic (sorry for reflections, couldn't get it better)

camera.jpg



aggie2347
Posts: 27
Joined: Sun Apr 22, 2018 8:30 pm

Re: Speed signs on dual carriageway

Post by aggie2347 » Sun Apr 14, 2019 12:06 pm

Cheers Pch for getting back to me. Unfortunately for me my VCDS cable is out of date and as such will not pick up the A5 module necessary to activate the multifunctional codes. So, before spending a shed load of money on a new diagnostic cable I will have to find out for certain whether or not the camera is fitted your picture seems to indicate that I don't. I will try the dealer before throwing in the towel. Thanks again for the photo.


Tomstring
Posts: 19
Joined: Fri Jan 04, 2019 7:23 pm

Re: Speed signs on dual carriageway

Post by Tomstring » Sun Apr 14, 2019 4:38 pm

Presumably the camera is picking up the national speed limit sign on the single lane slip road of 60mph which is technically correct and reverts to 70mph once it interprets it’s on a dual carriageway/motorway (?)


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Sash
Posts: 122
Joined: Sun Jan 27, 2019 11:15 am

Re: Speed signs on dual carriageway

Post by Sash » Sun Apr 14, 2019 8:37 pm

Just in case - some drivers think that any road with two lanes each way is a dual carriageway. If there is no barrier in the middle, it is still a single carriageway, where NSL applies even if there are four lines. NSL is 60 for a car, 50 for a van. If there is a barrier, it is a dual. If you see blue road signs it is a motorway. Easy. And btw if you are driving on a single carriageway with NSL, as soon as you see lampposts the limit changes to 30 even if it is not a built-up area. A lot of drivers are not aware of it.


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pch
Posts: 134
Joined: Sun Jan 22, 2017 8:05 pm
Location: Dublin, Ireland

Re: Speed signs on dual carriageway

Post by pch » Sun Apr 14, 2019 9:10 pm

Camera picks wide image which is processed and detects few type of objects including lane lines (for lane departure system) and few traffic signs.
It doesn't matter on which side of the road and at which height the sign is located.

I was driving through Europe from Ireland and the signs were recognised correctly in all countries: Ireland, UK, France, Belgium, The Netherlands, Germany, Poland, Slovakia, Czechia. In the manual there is full list. There were some errors with some strange values like 5mph or 15 km/h but they were edge cases.

From technical point of view I presume it's just some agorithm applied that if in field of vision there is something like round red with some symbols it will do Optical Character Recognition with the content inside the circle.

Apart of speed limits it can also detect other sign / cases:
- overtaking prohibited
- when towing (towbar opened) it will display extra speed limits or restrictions
- eg. in France there are two limits - for dry surface and rain - it can detect rain and display correct speed limit accordingly

Again - list of sign can be found on p. 232 in manual.

If the speed is not detected it's taken from Navi database. Same - if you change the road type / turn etc - it picks the default speed for that road only if it's in Navi db.


leWrat
Posts: 66
Joined: Sun Oct 14, 2018 8:42 pm
Location: United Kingdom

Re: Speed signs on dual carriageway

Post by leWrat » Mon Apr 15, 2019 10:13 am

Hi,
The way that I understand it is that the TSR will use the speed limit road information retrieved from the Nav maps data and only overrides it when is recognises a speed limit sign.
On the latest available (at time of writing) nav map the map has some speeds and road information wrong, e.g. on some dual carriageway the TSR sees the national speed limit sign but believes that it is on a single carriageway (from map info) and so shows 60mph instead of 70mph. I also have seen times where on some side roads where there are no speed signs at all, the map is reporting that I am on a 20mph road when in fact it is actually 30mph.

i.e. the TSR works correctly when it sees a "number" sign but on "ambiguous" signs like the NSL that depend on the type of road it then refers to the map to check type of road hence sometime reports wrong speed limit. If there are no signs it reports what the map says is the speed limit.
Shame really as the extra features that come with TSR, e.g. alert when more than x mph over speed limit, become useless as it regularly has wrong speed limit info and so gives false alerts.

Paul
MY19 Ateca Xcellence Lux 1.5 in Rhodium Grey with spacesaver wheel.


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