New map update out

[Sherwood]

Stanno is right, speed limits shown in the driver display are taken from traffic sign recognition system, not from map database. Driving along a road sector where workers placed a temporary speed limit for the day pops up immediately on my display.

..my experience is that this isn't necessarily so.

The displayed limit is a (complex) hybrid of traffic sign recognition and map data, depending on circumstances and the availability and frequency of signs. (Lack of signs meaning map data may be used). The manual seems to support this view.

When using auto speed limiter, however, it appears to me that this is largely based on sign data.

[WelshRobin]

I agree with Stanno. There is one stretch of road I use regularly where the change from 60mph to 40mph is displayed a good quarter of a mile before the sign. This has been the case ever since the 40 limit was introduced two years ago and it does not happen in other locations so I am pretty certain this info is from the map data and not yet corrected. On the other hand I too have noticed that temporary road works limits are picked up - must be from the intellisafe camera.

[WelshRobin]

Sorry Sherwood- it was your post I should have referred to, not Stanno’s.

[ChrisLF]

Fortunately I wasn't using automatic speed limiter when I was driving along a dual carriageway with a 70 mph speed limit towards Derby recently as a 30mph sign suddenly came up in the dislay as it had been picked up from a service road running parallel! How quickly would the car decelerate if ASL was engaged? Enough to potentially cause an accident?Also had it happen when signs picked up from side roads. Sometimes I don't get any speed limit in the display due to a lack of signs - no embedded data being used there.

As with some other areas there is going to have to be an awful lot of work done before implementation of self-driving vehicles, especially when sharing the roads with "normal" vehicles, if accidents are not to be caused by the technology.

[Sherwood]

How quickly would the car decelerate if ASL was engaged? Enough to potentially cause an accident?

..It can be quite abrupt if the speed is well over the wrongly read sign (think braking rather than simply throttle-off deceleration)

I tend to use ASL, and have a number of locations mentally noted where the car clocks a 30 limit off to the side in a NSL zone, or an early countdown sign for a 30 limit. I'm ready to click ASL rapidly off to avoid mild whiplash

The use of map data for speed limit display is detailed in the manual. It is substituted for sign-recognition data in various circumstances, but the write-up isn't clear, so best to use empirical evidence (I'm absolutely certain that I see data that doesn't emanate from sign-recognition. I'm also pretty sure that under certain circumstances I see the current limit, and an imminent change displayed, "stacked", which most certainly isn't sign recognition - though I may be deluding myself on the circumstances under which the speed limits are "stacked" on the display)

[SteveM]

Fortunately I wasn't using automatic speed limiter when I was driving along a dual carriageway with a 70 mph speed limit towards Derby recently as a 30mph sign suddenly came up in the dislay as it had been picked up from a service road running parallel! How quickly would the car decelerate if ASL was engaged? Enough to potentially cause an accident?Also had it happen when signs picked up from side roads. Sometimes I don't get any speed limit in the display due to a lack of signs - no embedded data being used there.

As with some other areas there is going to have to be an awful lot of work done before implementation of self-driving vehicles, especially when sharing the roads with "normal" vehicles, if accidents are not to be caused by the technology.

I have the identical scenario in my kneck of the woods ... we use the auto speed limiter on local (camera regulated) roads but also use a more convenient, quicker, parallel stretch of motorway. We have now learned that if usiing the ASL, approx 600m after joining the motorway, the car effectively performs what feels like an emergency stop to slow us to 40mph Luckily the motorway hasn't been too busy on those occasions but it's one heck of a shock when it kicks in. I suspected my map'data was out of date but I recently saw it updating as I was driving (auto) so it's not that

[Felindre]

Not noticed before, in the active display, when you have the map between the dials, along the bottom it gives the location, and I've just noticed at junctions it's now showing the lanes, which go right left and straight on, even when not got a route selected. Is this new or me only noticing after 11 months?

[ChrisLF]

Thanks for the replies which confirms my fears of what might happen. That's another "feature" that I will continue to not use along with Collision Avoidance and Stop Start.

It's one thing being able to disable ASL on regularly used roads but its main benefit should be where you don't know the roads but it's too risky for me.

I've noticed that stacking from time to time when the speed limits change but just assumed it was reading the upcoming signs.

[jamie307]

There was some long-term temporary roadworks on a dual carriageway near me with a 50 limit for about two years. My car still flashes up with a 50 limit sign on the dash despite all the signs and speed limit being removed a year ago and it just being a 70 all the way through with no signs at all.

I wouldn't dream of not permanently deactivating the auto speed limiter.

[Felindre]

Or put more simply, I wouldn't ever think of using the ASL.

Similar here, dual carriageway around Cowbridge (south Wales) has always been 50. However the last 2 times I've travelled it, it now has national speed limit signs at the start both ends. The car steadfastly shows 50 along it's length, and switches to 60 when it becomes single carriageway even though there's no further sign when it changes.