Cool, he vetoed one thing that I agree should have been vetoed.
People are not getting into speeding accidents because they don't know they are speeding. This would solve nothing, but would be a distraction any time it triggers off an incorrectly indexed speed limit.
Milton Keynes, in the UK, seems to have nailed this. It's effectively a grid of roundabouts. When the roads are empty, you can race along at 60mph (legally). As soon as it starts to build, the road naturally slows to 40, then 30mph. No cameras etc needed.
It also has the red ways. You can walk most places, without having to cross a major road. It uses underpasses for pedestrians and bikes etc.
One road I drive on frequently is posted 25, but Google Maps thinks it's 55, which is a silly speed for that road with many turnouts. Meanwhile, the next road over, is also 25 and Google sees that one correctly, but going 55 on that road is nearly natural, with nothing but the road and usually green traffic lights every quarter mile.
I wish tesla's and bmw's came with lane assist so that its harder to change lanes without a turn signal. also all cars should come with lights always on, so many cars in the early morning or dusk driving around with their lights off its hard to notice them