Comment This isn't the first trial (Score 1) 859
This was trialled* in Victoria, Australia about 2 years ago. Biggest problem was keeping the speed limits which change uptodate with the GPS speed zone GIS layer... which was very difficult.
I thought development had moved on from this rather dated tech to more car / sign interaction by putting sensors in signs that 'talk' to the car to let them know the speedzone.
* slightly different system though, when you sped the accelerator would push back at you harder and harder, so to go way over the speed limit you would be almost standing on the accelerator pedal.