Speed limit recognition is dodgy

[ptw]

It should work, but many times it doesn't. There are a lot of stories of it picking up the wrong speed limit from Wheelie bins with numbers on (or any sign with white lettering), side road speed limits in error. I suppose it's trying to do it's job, but on a straight major road I travel it mises the national speed limit sign and stats in the 40mph preceding it, then 100 yards further on it changes it to 60mph (which is what it should be). So, what's going on, is it cross referencing the speed limit through GPS like sat navs do? Possibly, because I had another instance where one part of a major road I use changed the limit from 50moh to 40mph bug every time I reach that point it changes it to 50mph. Does anyone have an answer? The local MG dealer doesn't ?

 

[Italy]

Detecting speed limit signs is merely an additional safety function.
As with all cars, this function can be improved and should not be a rule to be followed indiscriminately.

 

[IDC]

I also find it to be very unreliable. A local well used road that was 50mph was changed to 40mph after pavement widening. Lots of 40mph signs were put up, but the car mostly insists it is still 50, only occasionally showing 40.

 

[IDC]

I think it is just not very good at reading the signs and dealing with changes to the limit. It must have some sort of memory that was loaded with limits, probably connected to the sat nav. When the sign reader conflicts with the memory, it gets confused.

 

[Italy]

Sometimes, because you are distracted or because your vision is obstructed by a lorry or heavy rain, you ignore the current speed limit.
This device can be very useful.

 

[decrep]

Mine changes with every roadside sign. whereas google maps stays with what it remembers.

 

[ptw]

Mine changes with every roadside sign. whereas google maps stays with what it remembers.

You're lucky

Sometimes, because you are distracted or because your vision is obstructed by a lorry or heavy rain, you ignore the current speed limit.
This device can be very useful.

I agree, very useful, which is why I'm trying to find out what's happening and if it can be fixed

I think it is just not very good at reading the signs and dealing with changes to the limit. It must have some sort of memory that was loaded with limits, probably connected to the sat nav. When the sign reader conflicts with the memory, it gets confused.

That's by far the best possibility yet

Back in 2010 Ford put speed recognition as an option into a Focus and it worked perfectly well. The technology and quality of cameras are 20 fold better now, so why didn't it work properly.

 

[Alex144]

I think that the recognition works very well, but there is one situation in which it absolutely fails: On the German Autobahn. ?
Every now and then it happens that exits are marked with a speed limit. The sign for the exit is recognized (for example 60 km/h) and is displayed to me for the entire route until a new sign appears.
It would be quite fatal to drive 60 km/h on a German highway (which is without a limit in my case). ?

 

[decrep]

So what does the speed recognition do with "no limit" signs.
We used to have them here, it was just a diagonal line, but I don't think there's anywhere now without a limit. Some of those signs were slow to be replaced, but you were supposed to interpret them as meaning the blanket speed limit of 110, the cops wouldn't let you off on the grounds there was a no limit sign.

 

[Coulomb]

Does anyone have an answer?

Yes! Go fully metric! ??

The metric signs seem to be picked up better. My ZS EV Mark 1 picks up about 95% of the signs in Australia (a metric country since the 1970s). Unfortunately, it also picks up school zone times (and helpfully tells me that it's a conditional sign), and freeway exit speed signs. It's just too darned good!

I've got my hard hat on now.

We used to have them here, it was just a diagonal line,

Well, a diagonal line in a circle, if I recall correctly. Are you reaching back to the pre-metric days?

but I don't think there's anywhere now without a limit.

Central Australia, I believe.

 

[FromParis]

Speed is a very interesting topic for our MG3's hybrid+

Speed assist features are limited like :

Max regulated speed is 130kph (hopefully here in France that's the speed limit for autobahns/highways)

Speed limiter can be set to... 240kph (LOL)

Max speed is limited by software for not going over 180kph.. but just below (like 179..)

And torque is limited if you floor the accelerator pedal from 0, in any mode (eco / normal or sport)..

so I'd say things could be different if they were more fun @MG Motor with a proper "Sport" mode allowing no speed limitation, in case you drive on a german unlimited autobahn for eg. ... and if you have better tyres than the Solus HS63 like Michelin etc.. we could have better times from 0 to 60mph (or 0 to 100kph) and the car could be a little bit more savage and grippier around the corners or on a standing start !

 

[evor]

Must admit the MG3 is better at picking up the signs than my previous MG HS. HS used to recognise the National speed limit sign but always interpret as 70 whether Dual or single road. Nothings perfect, though must admit I still look at the Road signs and not rely on the recognition. Sorry officer the car recognised the 3 as an 8 didn't realise it was a 30 zone wouldn't work .

 

[decrep]

Well, a diagonal line in a circle, if I recall correctly. Are you reaching back to the pre-metric days?


Central Australia, I believe.

Yes diagonal in the same circle numbers are no in. Pre metric, maybe, time is all mixed up these days.

The NT hung on to no limit for a long time, but then introduced speed limits, but they may have gone back to no limit.

 

[Coulomb]

The NT hung on to no limit for a long time, but then introduced speed limits,

Ah, you are so right. 130 km/h is now the highest limit (81 mph).

 

[Alex144]

But the whole thing is very interesting. If you drive past a speed restriction sign, then the generally applicable speed limit for the road type is displayed.
In this case, 60 km/h was the limit due to road works, which means that 100 km/h is permitted after, as this is a federal highway and 100 km/h is generally permitted outside built-up areas (Here in Germany).
It would be interesting to know which source/data basis the vehicle uses.

 

[LDShadowLord]

I've seen similar behaviour, where the speed limit will change based on random numbers (It's favourite trick seems to be reading the Speed Limited signs on the back of trucks).
I'll be driving down the road and it'll happily tell me the speed limit is 80mph, which is interesting as that's not possible in the UK. It also likes reading road signs on factory entrances and informing me that the road limit is 5mph.
It does use GPS Data for some speed, as is required by EU Legislation (All new cars sold in Europe required to be equipped with speed limiters from this week | RAC Drive), and they clearly loaded the data a while ago as I live in Wales where the speed limits were changed to 20mph for default last December (versus the default 30mph in the rest of the UK) and it still reports 30mph from the GPS.

 

[ptw]

That clarifies a lot as yo what is going on. Thanks

 

[Italy]

Even if it's not a generality, on mine and in France I haven't seen any aberrations.

Perhaps this is the result of a recent software update.

 

[IDC]

Since this thread started, I have been paying more attention to my regular journey along the straight road that had its speed limit changed a few weeks after I got the MG3.

At one end, I enter the road from one that has retained its 50mph limit. The car usually ignores the first 40mph sign, but it consistently reads a second, repeater sign and shows 40mph. A bit further on and after going through a roundabout, it seems to forget that and it goes back to 50mph, which I presume is the memory from the sat nav. It then reads another 40mph sign and shows 40mph.

At the other end, entry was from a 30mph to 50 mph, but the 30 mph has been extended to cover a new crossing. The car consistently tells me the extended 30mph is still 50mph and it misses the new speed limit sign. The limit then rises to 40mph and I get the same back and forth between 40mph and 50 mph as it reads signs, but then its memory of the 50mph limit comes back.

I suspect a satnav update would solve the issue.

 

[IDC]

There is another section of road I use regularly, where briefly a 40mph limit road is parallel to a motorway and the MG tells me the speed limit is 70 in the 40. It then briefly changes to 40mph as the road turns away from the motorway and then it sees a 50mph sign and changes to that.