Is automatic traffic sign recognition black magic?

[PeteH]

Ok, I understand that a camera picks up speed limit signs as you drive past them, but how do you explain this:
Driving on country lanes around here, I pass a 'national speed limit' sign

And for a few seconds, the dash displays that symbol. Then, after a while, the car obviously thinks to itself "hang on, this is a single carriageway", and the display changes to


HOW DOES IT KNOW?
Spooky!

[RBH]

Ok, I understand that a camera picks up speed limit signs as you drive past them, but how do you explain this:
Driving on country lanes around here, I pass a 'national speed limit' sign
[ATTACH=CONFIG]3214[/ATTACH]
And for a few seconds, the dash displays that symbol. Then, after a while, the car obviously thinks to itself "hang on, this is a single carriageway", and the display changes to
[ATTACH=CONFIG]3215[/ATTACH]

HOW DOES IT KNOW?
Spooky!

This isn't new technology.

Anyone out in the car with their missus......will automatically know if they're speeding, too close to anything, going to slow, when to overtake etc...

[Drew]

It's a brilliant bit of kit and I rely on it quite a bit, but not fool proof. I know one village in Cornwall where as you pass through it in either direction the limit displayed changes from 30 to 40 when you are about half way through. No signs, nothing. You are quite clearly still in a 30 so why it changes I have no idea. It relies on nav as a back up to the camera so maybe something there is wrong! Makes me wonder though how fool proof autonomous cars like Teslas will cope when they are unleashed.

[exclusiv.]

does it also not rely on global positioning for speed limits too,,my daughter is a relatively new driver,and for insurance purposes she has a black box fitted,which monitors her speeds,,probs works along same lines