Incorrect Speed Limits causes accidents

Roadworks

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I am grateful, confused and overwhelmed, and today I planned to complete my belated tax return.
A couple of weeks ago I drove A404 northwards late one night and there was a long lane blockage from the HGV layby up to Marlow <> Bourne end roundabout, that roundabout blocked off too. I guess this is what you are referring and perhaps why it defaulted to 50mph on one recent run.

However the Monkton Lane location errors have been 100% repeatable for a year now.

That’s aside, I recognise that you have insights far deeper than conventional Here users and I have also been reading the Help Guide. So I would like to send you one edit screenshot of a specific location and ask if you recognise why it causes consistent error.s. I will send it shortly, then devote my day to HMRC.

Wow. Barry Greens questions on why his VW shows incorrect speed limits for only some sections of a road was fascinating, and well done for the Here Maps guy who seemed to take a lot of trouble to disgnose and help.
The explanation is interesting, because I have a Skoda Kodiaq, which uses Here Maps.
A road adjacent to where I live is a long straight road, with streetlights, and NO road limit signs.
Yet halfway down the road the car suddenly thinks the limit is not 30 as on the first half, but 20.
I have looked on the Here Maps Creator, and there are actually 6 sections (I think) along that road, and all state the speed limit is 30mph.
I use the limit warning to renmind me not to ‘drift’ over the posted limit, and on that one stretch, it drives me mad bonging away (albeit only for a short distance.
But I have noticed that occasionally my car will show a 20 limit when there are no signs tostate this.
I asked my Skoda dealer why this was wrong, and he said ‘if the car can’t see a speed sign, then it defaults to a ‘safe’ speed i.e. 20mph.
I asked whether this could be set as a user preference, but was told no, probably to stop the car default to 30, say, when its actually 20. But 20 limits are ALWAYS posted on signs, so that explanation sounds rubbish to me.

I guess my real question is – how DOES the car work out the limit for the road its on.
My original understanding was that the Here map database has limits marked for any section of road.
If the database doesn’t have a limit listed, or the car ‘Sees’ a speed sign that varies from its own map value, the nthe speed sign recognition takes precedence.
But the explanation of traffic reports of roadworks giving out old information is a new one on me.
I’m not aware of any raodworks for year on that road that specified 20mph, sh where the heck is the car getting its information from?

David; another example of VAG group’s inadequacy to produce latest self-drive vehicles.. After gathering more evidence I took my case direct to VW Head Office in the most politest and vociferous terms. My local dealer was used to pander me, then I eventually got to speak to the head office person in charge. She of course refused to accept any blame whatsoever. The conclusion is not to own any of VAG products or to disable the safety technology. (not tested during an MOT anyway)

Since my original post I have discovered repeated errors on dual carriageways too. I conclude in every case that the issue is relates to GPS locations. There is always lower speed limited road nearby. Either the inbuilt satnav is not accurate or calibrated properly. For example the error does not repeat when driving in the opposite direction (although yes the safe 20mph default issue can apply when the sky is heavily over-clouded).

I do see a viable solution, which is measurable and prove’able by techno’s like us. But I fear this would not be taken on board by HERE. My solution is that the sideroad MPH GPS locations are set to a minimum of x metres away from the thru carriage speed limit. That way the vehicle will not be distracted.

For sure, is databases like HERE sit together with responsible Vehicle Manufactures, then issues will surely be solved !

Barry: being the curious type I am, I looked to see if I could find how the speed limits are stored in the map data.
I’ve done this sort of thing before looking at how WindowsMediaPlayer stored my music content. A bit of poking about with SQLite soon sorted that out.
This is different, though. I can see the structure sql tables, but not the actual map data. I was hoping to confirm that the speed for the road I am having problems with is correctly stored.
But from what you say, that might not help, even if I could find the data.
Once you mentioned the presence of nearby roads with a different limit than the one I am on, I looked at the map again.
There are two roads off this road, both with 20 mph limits posted.
So it may be that the car is ‘seeing’ that nearby limit and getting confused whether it applies to where the car thinks it is. The actual position of the on the sat nav map is always fine.
Sounds very plausible, though, but not sure anything can be done to fix it 🥹

What is very clear David is that the false vehicle alarms/responses are 100% reproducible. That is anyone who drives (with a VAG so far) can reproduce the same issues. Even when I copied a similar thread like Here’s, from another site, direct to VAG management top brass, there was nothing but total denial. My local VAG service manager admitted to me that his personal vehicle had the same issue.

I conclude that it is too bothersome or too expensive for VAG to solve the fault. Or, too expensive to implement the software updates to present day vehicles. I would of thought EU regulations would have thrashed it out by now.

I guess this particular notice board is of no use either as the chat is very much limit to us two.

Would be nice to see Brussels or VAG solve the issue. It may help to solve a major crash and injury someday ! If dashcams could see the issue from where the driver sits (instead of behind the rearview mirror). we could send actual dash recordings to Brussels and Social Media.

Perhaps my GoPro headset will be of use – yes – I must plan ahead………