Eventually, I expect we'll have some national standard for wireless transmitters on traffic signals, so they can send a message (timestamped and cryptographically signed with the state's department of transportation's public key) to the cars to tell them unambiguously when to stop and when it's safe to go.

(This could help human drivers too; just add a red/yellow/green light to the car dashboard for those times when you can't see the actual light because there's a big truck in the way, or the sun is directly behind the traffic signal.)

I also expect that by the time this sees near-universal adoption, we'll already have the image recognition corner cases mostly worked out.

Las Vegas has some communication from traffic signals to vehicles [1]. I can't tell from the article how it is implemented; it might just be that the city's traffic control computer sends traffic light information out, instead of individual lights communicating.

[1] http://www.theverge.com/2016/12/12/13923254/audi-v2i-las-veg...

A nitpick, but you would sign with the private key, and verify with the public key.

Thanks, that's what I meant.

How about "Signal Ahead" light boards on the back of semi trailers, which relay the traffic signal to the cars behind. Like Flashing Rear End Devices on trains, which operate by telemetry and function as red signals.

Ought to be maintenance free and a nice way for the big trucking lines to differentiate their public face - similar to those aero ground effects that are showing up on trailers.

Wouldn't the average human be fooled by those things?

Please don't get driver's license.

Possibly, but I imagine the incentive isn't really there. Someone intentionally doing that would be penalised and for minor gain. Someone could do it now to fool human drivers and it hasn't really happened.

e.g., stand in hi-vis at an intersection holding a "Slow" sign regardless of the red light above.

The system is likely capable of distinguishing a lit green light from a sign painted like one. If you're simply asking "would the system be fooled if someone nefariously hung an always green light where a red one should be" surely that is a circumstance that would fool a human as well.

I'm not convinced it would distinguish the two.

Perhaps the most concerning thing is that someone could create a nefarious image that's not obviously nefarious to humans. I mean, we've all seen the very slight adjustments required to trick state-of-the-art image classification systems into thinking a cat is really a crocodile.

>The system is likely capable of distinguishing a lit green light from a sign painted like one.

I doubt it. It's not even clear that it shouldn't treat a painted green dot like a green light.

Another good question is what does the car do if the stop sign or traffic light is obscured by trees?

I swear to good the city of San Francisco could car less about this issue. I've gotten to the point where I look for the painted STOP on the road, rather than the stop sign.

I assume either the computer could recognize the painted letters on the road (they are often in bad shape) or the GPS would inform the computer that a stop sign exists? So it doesn't have to look for it?