Speed limit sign camera - USA vs. Europe / UK?

GreenT said:

I ask as, I rented a car in the UK a while back and its GPS/NAV included the speed limit on the nav but the car contained no camera. So the nav "databases" in the UK must contain speed limit information for the roads?

Why then would Tesla reinvent the wheel if they have?

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Same in the U.S. - GPS maps generally know posted speed limits.

However, they don't know the speed limit for a construction zone. You won't be able to safely navigate by maps alone.

Also, lots of places in the U.S. have variable speed signs that depend on current traffic and time-of-day. Also not something you can read from a map.

NAV data isn't always up to date. My TomTom still doesn't have speed data for a number of state highways where I live. On top of that, there are legal liability implications to consider when used for autopilot. Let's say you configure the car for the speed limit, the data is wrong, and you receive a citation. Tesla would likely be held liable for this, and then would have to go to the trouble of holding the NAV data source liable, too. Liability in case of an incorrect road sign (or because it was vandalized, e.g. spray-painting a "35" to become "85"), Tesla is less likely to be liable because it's between you and the vandal unless the behavior was silly, like believing a fake 135 MPH sign.

In addition, it won't know road works limits when local projects are underway, because nav data isn't updated all that quickly. The camera helps to identify specialty limits (although not all of them - here we have special school district zones on state highways that are only active during certain hours). While some of the auto-pilot capabilities today are officially limited to controlled highway use, we have to think further forward.

But to the original point - a camera helps to make sure that local projects and changes are reflected before the nav data gets updated; considering the Tesla's nav vendor still hasn't updated maps to include a new Interstate bridge that opened over a year ago, I'd rather trust the camera.

...but I am interested in how these systems play out in the future. I suspect we'll see standardized, government-sponsored speed information in the future, so that we don't have to rely upon compiled databases.

I believe Mobileye currently recognizes 250 signs & they expect to reach 1000 sometime this year, I presume Tesla will add them as they become available.
The Future of Computer Vision and Automated Driving by Prof. Amnon Shashua - YouTube

deonb said:

Also, lots of places in the U.S. have variable speed signs that depend on current traffic and time-of-day. Also not something you can read from a map.

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Many years ago when I was a kid, I remember some US Interstate signs would change at night when the headlights hit them (I think they went from 75 in the day to 65 at night). Some sort of prism or reflector setup as I recall.

The camera correctly interprets our speed signs in Australia. Black numbers on white background surrounded by red circle.

I can confirm it reads the signs by the side of the road in The Netherlands perfectly. White signs, black lettering, red circle around it.

It also reeds Norwegian road works speed limit signs, they are round with red circle and black letters but on a neon green background.

While on a UK test drive a couple of weeks back the salesman pointed out that the camera was reading the speed signs; and it did flash up on the dash - a UK 40mph sign in this case.

Ford's new car will force you to obey the speed limit

A camera mounted on the windshield scans the road signs on the sides of the highway and, when the vehicle enters a 20mph zone, the system reduces the top speed to match. Rather than controlling the speed with automatic braking, the car limits its own velocity by adjusting the amount of fuel being pushed to the engine.

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It does not seem to recognise the built up area and built up area ends signs though, which essentially in Sweden is a 50 km/h and a 70 km/h speed sign respectively (other limits in other countries). It seems to pick up the speed limit change by position rather when entering or leaving a village or town.

Those are unique! I have never seen anything like that before!

deonb said:

Also, lots of places in the U.S. have variable speed signs that depend on current traffic and time-of-day. Also not something you can read from a map.

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Variable speed limits are much more common in Europe than in the US. Saw them all the time when I lived in Europe in '95 and '99... The only place I've seen them in the US is in the Seattle area -- and I think those are relatively new...

Of course in the Netherlands we also have this: cancel all previous speedlimits and return to the normal speedlimit for this kind of road. Since even most drivers here don't seem to know that, it is hardly surprising the Tesla does.

I get a lot of false-positives with the speed limit sign recognition. For example, if I'm cruising down the freeway at 110km/hr and there is a yellow "suggested speed" exit ramp sign... all of sudden the dash goes nuts thinking I'm travelling at an excessive rate of speed. Also, there are signs that show "80km/hr up ahead" and the system picks them up as being the suggested speed at that time. Obviously still a lot of work to do to eliminate false positives.

I would hate to be driving with Autopilot and the car suddenly slows down to 40 km/hr on the freeway because it read an exit speed sign!

Has anyone had to deal with how it responds to school speed limits? They usually drop to 20mph (35mph on rural highways) but only during certain times of the day. I can see a problem cruising down a highway at 60mph with cars behind me and suddenly it tries to slow down to 35 when the school zone isn't in effect.

As I have an 'old' model S without the cameras, I am wondering:

Does the MS recognize that when you make a right or a left turn, leaving a speed restricted road, the speed limit is no longer valid.

I drove a friend's MS yesterday (thank you Thomas) and it didn't get it. I left a rural road which was restricted to 70 km/h and turned into a road without any restriction (so the general restriction to 100 km/h for non Autobahn roads is in effect). It still signalled me a 70 km/h speed limit.

Is that normal behaviour? If yes, I would like to report a bug.

Johann Koeber said:

As I have an 'old' model S without the cameras, I am wondering:

Does the MS recognize that when you make a right or a left turn, leaving a speed restricted road, the speed limit is no longer valid.

I drove a friend's MS yesterday (thank you Thomas) and it didn't get it. I left a rural road which was restricted to 70 km/h and turned into a road without any restriction (so the general restriction to 100 km/h for non Autobahn roads is in effect). It still signalled me a 70 km/h speed limit.

Is that normal behaviour? If yes, I would like to report a bug.

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Yes, a lot of false-positives. Will be interesting to see how Autopilot functions in real life.

dvroegop said:

Of course in the Netherlands we also have this: cancel all previous speedlimits and return to the normal speedlimit for this kind of road. Since even most drivers here don't seem to know that, it is hardly surprising the Tesla does.

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"Tesla does"? You mean

Bef 2015: 40 signs in 25 countries
Beg of 2015: 250 signs in 50 countries
End of 2015: 1000 signs in 100 countries

Source: CTO of Mobileye in which Amnon Shashua talks about how Mobileye is incorporating deep learning into its self driving car research.
The Future of Computer Vision and Automated Driving by Prof. Amnon Shashua - YouTube

K5ING said:

Has anyone had to deal with how it responds to school speed limits? They usually drop to 20mph (35mph on rural highways) but only during certain times of the day. I can see a problem cruising down a highway at 60mph with cars behind me and suddenly it tries to slow down to 35 when the school zone isn't in effect.

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School zones are probably not the best place to be using autopilot, a feature intended for on-ramp to off-ramp highway cruising, so I'd say this edge case is explicitly out of scope.

Do you actually have school zones in the middle of highways where you live? I'd say in that case it would be on you, the driver, to recognize it was time to disengage autopilot and take over manual control.