2019+ Corolla Speed Limit Detection

[AndrueC]

I seem to recall that previously some people have said that the Corolla only uses its camera to determine the speed limit. Well it occurred to me tonight on the way home that it can't just be that. There's a short stretch of the A422 near Brackley in between the A43 and Banbury road which had been a 50 mph zone (like most of the A422 to the M40). However at some point fairly recently the limit was raised and now that mile or so is NSL.

The thing is that when I turned off the A43 (dual carriageway, car shows the limit as 70) onto the A422 the car showed the limit as 50 mph. There is no longer any signage to that effect. In fact there is nothing at all and I think it ought to have an NSL sign(*) but that's neither here nor there. My point is that in the absence of a 50 mph sign the car can only be getting that information from the satellite navigation. This confirms another case nearby where the car shows 60 too early because it seems unaware that the NSL zone was moved to accommodate the entrance to a new housing estate.

(*)Apparently the regulations don't require it. Councils now have discretion and can omit signs if they don't think they convey useful information. Personally I think the limit is poorly signed but I suppose it's only locals who might not realise it's now NSL.

[Sidrat]

I have a place near where I work that goes from national speed limit to 30 entering a village, after 20 yards I turn left and the limit goes back to national (normal large signs either side of the road), the car still indicates 30.  After quarter mile limit goes to 30 again.  When I go in the opposite direction I get the same.  I think it uses speed limits in the sat nav as it's main reference and the camera as a back-up.

[Timmon]

Yes, Andru, I can confirm my car does the same. The van has a Garmin portable device, and that also bings and bangs at me to warn I am doing above 50 on that stretch of road.

I guess it makes sense to give the Sat nav priority. Many road signs are completely obscured by vegetation at the moment, so if the car relied on the camera, it would probably just keep throwing us the nsl indicator. Not sure what purpose the camera has, if the sat nav over rules it. In the case of the A422, I doubt the camera can see any speed signs, it is so poorly sign posted. I certainly didn't see them until you mentioned it the other day.

[Devon Aygo]

Primary source of limit information is from the navigation but the TSS camera can also show information in lieu of navigation & override the navigation if it see's a sign to the contrary

[Sidrat]

32 minutes ago, Devon Aygo said:

Primary source of limit information is from the navigation but the TSS camera can also show information in lieu of navigation & override the navigation if it see's a sign to the contrary

But it does not override the navigation, the signs on my route go to 30 then national limit for quarter mile then 30 but the car displays 30 all the time even though the signs clearly change and are not obstructed!  

[AndrueC]

1 hour ago, Devon Aygo said:

Primary source of limit information is from the navigation but the TSS camera can also show information in lieu of navigation & override the navigation if it see's a sign to the contrary

And if you find an error in the navigation. Fix it. I've already updated the map for A422 🙂

[Timmon]

I can't remember how to do that! 

[AndrueC]

3 hours ago, Timmon said:

I can't remember how to do that! 

It's not simple. For that speed limit change I had to modify the speeds on several sections of road. Exit from A43 roundabout, a short stretch after that. A long stretch up to the Hinton turn. The Hinton Turn. Most of the rest of the road to Banbury road then the approach to the Banbury road roundabout. It doesn't seem possible to just say 'from here to here is 60' 😕

Could have been worse though. I corrected this to show that Tramway Road was no longer a through route and that took an hour of fiddling around. Dunno how many people's time I saved with that one but it was offering that as a way of avoiding the A4260 so it could've been any number of people.